Thinning edges from synthetic hair: how long does repair take?

Last updated 2026-07-09

Why does synthetic hair cause thinning edges in the first place?

Weight and tension. That's the short answer. Synthetic hair, whether it's a box braid extension, a crochet install, or a sew-in with a synthetic weft, is heavier than your natural hair and almost always attached under some degree of pull. That pull lands on the hairline, the thinnest and most fragile section of the scalp, and over days and weeks it physically stresses the follicle.

The clinical name is traction alopecia. The American Academy of Dermatology describes it as hair loss caused by prolonged or repeated tension on the hair ^[1]. It usually starts at the temples and the nape, exactly where braiders anchor styles and exactly where your hairline has the least follicular density to spare.

Synthetic fiber makes this worse for specific reasons. It doesn't move the way natural hair does. Natural hair flexes and spreads tension as you turn your head. Synthetic fiber is stiffer, so the anchor point takes almost all of the mechanical load. Synthetic braids also tend to stay in longer than human-hair extensions, partly because they cost less and partly because they tangle less, so your cumulative tension exposure climbs. On top of all that, edge-laying gels and edge controls (especially the alcohol-heavy ones) go on over follicles that are already stressed, drying the hairline out and making the shaft brittle right at the root.

None of this means synthetic hair is off-limits. It means the install method and how long you keep it in matter enormously.

What does early traction alopecia actually look like?

Early traction alopecia has a signature. Your hairline looks like it's pulling back in a thin, even line across the temples, and sometimes along the nape. Broken hairs sit shorter than the rest of the hairline. Small follicular papules (tiny red bumps right at the follicle opening) are often the first sign that inflammation has started, before any visible thinning shows up ^[2].

Watch for hair that used to lay flat and now lifts at the temples. Those shorter hairs are breakage regrowth, not thick healthy new hair coming in. You may also spot a row of fine, wispy hairs sitting behind the main hairline like a little fringe. Dermatologists call this the "fringe sign," and its presence usually means you're still in the reversible early stage ^[2].

Pus-filled bumps, scaling, or bald patches with no visible follicle openings are a different story. That's when scarring becomes the concern. At that point you need a dermatologist, not a product swap. For most people reading this, though, the thinning is moderate and caught before scarring, and the outlook is genuinely good with the right changes.

One rough test: if you can still see small hairs in the thinning zone, the follicle is alive. If the skin looks smooth and shiny with no hair at all, that follicle may be scarred. It's not perfect, but it's a useful first screen.

How long does it actually take for thinning edges to grow back?

Everyone wants a precise number here, and the honest answer is that it depends on how long the damage was building and whether any follicular scarring set in.

Hair grows about 0.5 inches (1.25 cm) per month on average, though that shifts with your age, hormones, and scalp health ^[3]. That rate tells you very little on its own, because the first job isn't growing length. It's getting the follicle out of the disrupted growth cycle the tension caused.

Here's a practical breakdown drawn from clinical descriptions in the literature:

Severity	What you see	Typical timeline for visible improvement
Mild (early)	Fine wispy hairs, slight recession, fringe sign present	3 to 6 months after tension removed
Moderate	Clear thinning at temples or nape, follicles visible	6 to 12 months
Severe (no scarring)	Significant recession, sparse follicles still visible	12 to 18 months or more
Scarring (fibrosing)	Smooth skin, no follicle openings, possible itch/burn	May be permanent; dermatology referral needed

These ranges come from how follicular recovery is described in traction alopecia literature and general hair cycle biology, not from a single clean randomized trial, because nobody has run one on synthetic hair specifically ^[4]. The closest data comes from studies in populations with high rates of traction alopecia from braiding, and those consistently show that stopping the tension early leads to recovery in most cases.

Here's a number to hold onto: a 2016 study in the Journal of the American Academy of Dermatology found traction alopecia in 31.7% of women of African descent surveyed, one of the most common causes of hair loss in this group ^[4]. That prevalence means dermatologists see this constantly, and it means you are not an outlier.

One more honest point. "Visible improvement" and "full density" are not the same thing. Edges often come back thinner than they were before an episode of traction alopecia, and each new episode stacks on top of partial recovery. That's why stopping the source of tension matters more than any bottle you can buy.

Mild (fringe sign, slight recession)	4
Moderate (clear thinning, follicles visible)	9
Severe (significant recession, no scarring)	15
Scarring/fibrosis (smooth skin, no follicle openings)	0

Source: Samrao et al., International Journal of Dermatology, 2019; hair growth rate, NIH MedlinePlus

What speeds up edge regrowth after synthetic hair damage?

The intervention with the most evidence behind it is also the least exciting: take the tension off. Every week a tight install stays in is a week your follicles spend under stress. Resting your scalp between styles isn't optional. It is the treatment.

Beyond that, a few things have real support.

Minoxidil (topical) is the one FDA-cleared treatment for hair loss with a meaningful evidence base. The 5% solution or foam has been studied for androgenetic alopecia, and dermatologists recommend it off-label for traction alopecia when the follicle is still intact ^[5]. If your thinning has run on for months, a dermatologist visit to talk about minoxidil is worth your time. It does nothing for scarred follicles.

Scalp massage. A small 2016 study in Eplasty found that standardized scalp massage raised hair thickness over 24 weeks, with the researchers suggesting mechanical force may stretch dermal papilla cells and support the growth phase ^[6]. Four minutes a day is what they tested. It's free, it won't hurt anything, and it moves blood to the area.

Protein and iron. Hair is keratin, a protein, and iron deficiency is one of the most common nutritional drivers of extra shedding. If your diet has been low in protein or you've had heavy periods, bloodwork to check ferritin is genuinely useful. Serum ferritin below 30 ng/mL is tied to hair shedding in some studies, though the exact cutoff is still argued ^[7].

Gentle handling. No tight rubber bands. No hard-bristle brushes along the hairline. No sleeping without a satin or silk scarf or pillowcase. None of this regrows hair by itself, but it stops adding fresh insults to a zone that's trying to heal.

Natural oils on the scalp (castor oil, peppermint oil diluted in a carrier) have plenty of anecdotal support and some early lab data, but no clinical trial data specific to traction alopecia recovery that I'd call solid. They're low-risk, so if they're already in your routine and your scalp tolerates them, keep going. Just don't expect an oil to do the job that removing tension has to do.

Edge Naturale's growth products are made without harsh chemicals for women managing exactly this kind of edge damage. They slot into a gentle-handling routine well, but like every topical, they work best once the source of tension is gone.

Which synthetic styles are hardest on edges, and which are safer?

Not every synthetic style loads the hairline the same way. Knowing which ones carry more risk helps you make smarter calls without giving up protective styling completely.

The highest-risk installs share a few traits: very small braids anchored close to the hairline, heavy extensions (think jumbo box braids packed with synthetic hair per section), styles worn 8 weeks or longer without adjustment, and anything that asks your hairline hairs to hold weight they were never built for.

Knotless box braids, done right, spread tension more evenly than traditional feed-in braids that use a knot at the root. The difference is real, not marketing. Knotless braids begin with your own hair and add extension hair gradually, so there's no tight anchor knot yanking against the scalp follicle from day one.

Crochet styles installed over a loose, flat cornrow base (rather than tight ones) run lower-tension than full box braids, because your natural hair isn't carrying the whole weight of the extension braid.

Sew-in weaves with a leave-out are consistently rough on edges, particularly the ones that need the hairline to lay flat and get glued or gelled again and again. Chemical stress from gel plus physical stress from laying and re-laying a fragile zone is a bad pairing.

Wigs on a wig cap are the lowest-tension option if you struggle with traction alopecia. Your edges aren't anchoring anything. The catch: tight wig bands and glued lace frontals create a different but equally real tension line, so even wigs need to be sized and worn with some thought.

Here's the field test. If your scalp hurts after an install, that pain is telling you the tension is too high. A well-done protective style should not hurt. Braiders who wave off discomfort with "it'll loosen up" are technically right that it loosens, but the follicle damage happens in the first 24 to 72 hours of peak tension.

Can traction alopecia from synthetic hair be permanent?

Yes, if it goes far enough. This is the part that deserves honesty over reassurance.

The follicle can take a lot. Short-term tension causes reversible inflammation. But if that inflammation drags on, or if the tension is extreme, the follicle undergoes fibrosis: scar tissue fills in around it and it can no longer produce hair ^[8]. Once that happens, no topical, no massage, and no diet change brings hair back there.

A 2019 paper in the International Journal of Dermatology reported that early-stage traction alopecia is usually reversible but that "chronic and severe traction may lead to permanent follicular damage," pointing to fibrous tract formation on scalp biopsy as the marker of irreversibility ^[8].

The practical takeaway: don't wait years to deal with thinning edges. If you've been managing thinning edges for more than 12 months with no improvement, see a board-certified dermatologist. A scalp biopsy can tell you whether fibrosis has set in. That answer changes the plan, because non-scarring alopecia responds to the interventions above, while scarring alopecia needs different treatment that only a dermatologist can prescribe.

Most people reading this are not at the scarring stage. Awareness usually shows up earlier. But "it'll grow back eventually" is a dangerous assumption if you keep reinstalling tight styles with no recovery time in between.

How should you care for your scalp and edges during the recovery period?

Recovery has two phases. First you stop the damage. Then you build the conditions where the follicle can do what it wants to do anyway, which is grow hair.

Phase one, the priority list: take the style down (or don't reinstall for at least 4 to 6 weeks), wash your scalp gently with a sulfate-free shampoo to clear product buildup that can clog follicles, and cut out anything that adds heat or chemical stress to the hairline. No flat-iron on the edges to help them lay. No relaxer touch-ups that bleed onto the hairline. No gel loaded with alcohol.

Phase two starts once the follicles are off active stress.

Keep the scalp clean. Sebum buildup and product residue don't cause alopecia, but they can feed inflammation that slows recovery. Washing the scalp (more than the hair) every one to two weeks, or more often if you sweat a lot, is a reasonable baseline.

Moisturize the hairline. Your edges dry out faster than the rest of your hair because they're finer and more exposed. A light oil, a hair butter, or a leave-in along the hairline helps stop breakage in the new growth trying to come through.

Leave it alone. New growth in a previously thinned zone is fragile. The urge to lay it down, to make it look neat, can snap it clean off before it ever thickens. Let it do its thing.

Ride out the fringe stage. There's almost always a stretch where new growth looks thin, short, and wispy before it catches up to the rest of the hairline. This can last several months, and it looks worse before it looks better. That's normal. It is not a sign that regrowth has stalled.

For product support during recovery, you can look at Edge Naturale's natural edge growth collection and read our review of a popular edge control option that's gentler on compromised hairlines.

Does diet or nutrition affect how fast edges grow back?

Yes, but nutrition is a supporting player, not the lead. Removing tension is still job one.

The nutrients most consistently tied to hair growth and shedding in the literature are iron, biotin, zinc, vitamin D, and enough total protein. Of these, iron deficiency is the most common and the most under-diagnosed in women, especially those with heavy menstrual cycles or low-meat diets ^[7].

The NIH Office of Dietary Supplements notes that iron works in DNA synthesis and that rapidly dividing cells, follicular cells included, are among the first to feel a deficiency ^[9]. Bloodwork covering a complete blood count and a ferritin level is a reasonable move if your edges aren't budging despite good scalp care. If ferritin is below 30 ng/mL, supplementing to raise it (under medical supervision) may cut shedding.

Biotin gets a lot of hype for hair growth, and the evidence is thinner than the marketing. The NIH notes that biotin deficiency does cause hair loss, but true deficiency is rare in people eating a varied diet ^[10]. If you're not deficient, more biotin won't speed anything up. It can, however, throw off thyroid lab panels and interfere with certain blood tests, so tell your doctor if you take it.

Protein is the structural material of hair. Women eating below roughly 45 to 50 grams of protein a day (the general adult RDA per USDA is 0.8 grams per kilogram of body weight) may see slower recovery ^[11]. This hits harder for women who've lost a lot of weight fast, since crash diets are a known trigger for telogen effluvium (widespread shedding), which can pile onto traction alopecia.

Diet, in short: fix your deficiencies, eat enough protein, and don't count on supplements to cover for ongoing mechanical damage.

When should you see a dermatologist about edge thinning?

There are clear signals that home care isn't enough and a dermatologist (ideally one who works with hair loss or traction alopecia in textured hair) is the right next step.

Go if any of these are true: the thinning has run more than 12 months with no improvement; you have areas where the skin is smooth and shiny with no visible follicle openings; you have persistent itching, burning, or tenderness at the hairline; you notice thinning in spots your style doesn't touch (which can point to a different type of alopecia, like alopecia areata or frontal fibrosing alopecia); or you've kept tension off for 3 to 6 months and seen no change at all.

Frontal fibrosing alopecia (FFA) is worth knowing about because it looks a lot like traction alopecia but is a separate condition, an autoimmune-mediated scarring alopecia that needs different treatment ^[12]. The two get confused, and FFA can get much worse while someone waits on "traction alopecia regrowth" that will never come. A dermatologist can tell them apart.

The AAD keeps a find-a-dermatologist tool on its website ^[1] and flags traction alopecia as preventable and treatable when caught early. Per AAD guidance: "Treatment of traction alopecia includes avoiding hairstyles that pull the hair. If the hair follicles are not damaged, hair regrowth is possible" ^[1].

If cost is the barrier, many university-affiliated dermatology programs see patients at reduced rates, and federally qualified health centers (FQHCs) can point you to a referral. HRSA has a locator at findahealthcenter.hrsa.gov ^[13].

What hair care habits make the biggest long-term difference for edge health?

The habits that protect edges over the long haul aren't complicated. They're just easy to skip when a style looks good.

Rest between installs. Four to six weeks between back-to-back tight styles is a commonly cited guideline in traction alopecia prevention resources, though the evidence is more anecdotal than clinical. The logic holds: the follicle needs time out of tension to finish a healthy growth cycle. Skipping rest is where cumulative damage piles up.

Ask your braider for lower tension. "Not too tight" is a legitimate instruction, and a good braider respects it. If a braider tells you tighter lasts longer or that it won't hurt after a day, find a different braider. You can also ask for braids to start further from the hairline so you're not anchoring in the most vulnerable zone.

Cap your wear time. Most professional guidance on protective styles suggests no longer than 6 to 8 weeks for braids, and 4 to 6 weeks is safer if you have a history of traction alopecia. Past that, the style gets heavier as it grows out, lint collects at the scalp, and tension on individual hairs from the style loosening actually rises instead of dropping.

Protect at night. Satin bonnets and satin pillowcases cut friction on the hairline while you sleep. Cotton pulls moisture out and drags. Small thing, but it compounds over hundreds of nights.

Check your edges monthly. Take a photo in the same light from the same angle. Changes are often gradual enough to miss in the mirror but obvious when you line up photos three months apart. Early detection is the whole game with traction alopecia.

Are there products that genuinely help with edge regrowth?

Honest answer: the "edge regrowth" product category is wildly over-marketed relative to the evidence for any one product.

Minoxidil is the single ingredient with FDA clearance for hair regrowth and a real evidence base ^[5]. If you want a topical that's actually been studied, this is it. The 2% and 5% formulas are both over the counter. The 5% foam tends to win on ease of use. It needs consistent daily application and takes at least 4 months before you see meaningful results. Some people shed more in the first few weeks, which is a normal part of the follicle cycling response, not a sign it's backfiring.

Castor oil comes up constantly in the natural hair community. The research is mostly in vitro or anecdotal. No clinical trial proves castor oil regrows hair, but ricinoleic acid (its main fatty acid) has shown anti-inflammatory properties in lab studies ^[14]. Less inflammation at the follicle could, in theory, help a recovering follicle. It's low-risk and cheap, so keep it in a routine if you like it. Apply it to the scalp, more than the hair shaft.

Peppermint oil diluted in a carrier had one genuinely interesting animal study where it outperformed minoxidil on hair count, but that was in mice, and no human trial has repeated it ^[15]. Dilution matters. Undiluted essential oils cause contact dermatitis, the last thing a stressed scalp needs.

Products made specifically for edges (natural growth oils, serums, butters) mostly work by moisturizing the hairline, cutting breakage in existing hair, and keeping the scalp environment favorable. That's real value. Just be clear-eyed about it: they don't force dormant follicles to switch on. They support follicles already trying to recover.

For a curated selection made without sulfates, silicones, or harsh alcohols, the Edge Naturale product collection is worth a look if you want natural options that fit the gentle-handling approach above.

Frequently asked questions

How long does traction alopecia from braids take to grow back?

Mild traction alopecia from braids usually shows visible regrowth within 3 to 6 months once tension is completely removed. Moderate cases take 6 to 12 months. The timeline depends heavily on how long the tension was in place and whether any follicular scarring has occurred. If you still see small hairs in the thinning area, the follicle is likely still active and recovery is possible.

Can synthetic braids permanently damage your edges?

Yes, in severe or long-standing cases. Prolonged tension from synthetic braids can cause fibrosis around the follicle, which makes hair loss permanent in that area. A 2019 paper in the International Journal of Dermatology confirmed that chronic and severe traction may lead to permanent follicular damage. The earlier you stop the tension, the better your chances of full recovery. Smooth, shiny bald patches with no visible follicle openings are the warning sign.

What helps thinning edges grow back faster?

Removing the source of tension is the most important step, and nothing else works as well without it. After that, evidence supports topical minoxidil (the only FDA-cleared topical for hair regrowth), regular scalp massage, correcting nutritional deficiencies (especially iron and protein), gentle handling of the hairline, and consistent moisture. No product or supplement overrides the need to rest from tight styles.

Is it normal for edges to thin after taking out braids?

Yes, and it's common enough that it has a name: traction alopecia. Some shedding when taking down braids is normal, since hairs that shed during the wear period have been held in by the style. But if your hairline looks noticeably thinner after removal, that's a sign the tension was too high, the style was in too long, or both. Rest the scalp before reinstalling.

How can you tell if your edge thinning is from traction or something else?

Traction alopecia typically follows a pattern: thinning at the temples and nape in a line that mirrors where your styles pull, often with a fringe of short wispy hairs behind the main hairline. Alopecia areata causes round or oval bald patches anywhere. Frontal fibrosing alopecia causes recession across the entire front hairline, often with eyebrow loss. If the pattern doesn't match your style history, see a dermatologist for a proper diagnosis.

Do edges grow back after crochet hair causes thinning?

They do in most cases, as long as the crochet install wasn't too tight and the thinning is caught early. Crochet styles can be lower tension than traditional box braids, but tight cornrow bases still stress the hairline. Remove the style, rest for at least 4 to 6 weeks, keep the scalp clean and moisturized, and watch for early regrowth signs (the fringe of new, short hairs) within 3 to 6 months.

How do you stop edges from thinning while still wearing protective styles?

Choose styles with lower tension at the hairline, like knotless braids or wigs on a wig cap. Limit wear time to 4 to 6 weeks maximum. Ask your braider to start braids further from the hairline. Take rest periods of at least 4 weeks between installs. Apply a light oil to the hairline daily during the wear period and protect it at night with a satin bonnet or silk pillowcase.

Does castor oil actually help regrow edges?

There's no clinical trial proving castor oil regrows hair in humans. What we know is that ricinoleic acid, its main component, has anti-inflammatory properties in lab studies, and reducing inflammation at the follicle may support recovery. It's very low-risk and inexpensive, so it fits logically into a recovery routine. Apply it to the scalp rather than just the hair shaft. Don't expect it to substitute for removing the source of tension.

When is edge thinning too severe to treat at home?

See a dermatologist if thinning has continued for more than 12 months without improvement, if you have smooth bald patches with no visible follicle openings, if you're experiencing persistent burning or itching at the hairline, or if you suspect the pattern doesn't match traction alopecia. Frontal fibrosing alopecia is a separate condition that worsens without medical treatment and can be mistaken for traction alopecia.

Does minoxidil work for traction alopecia from synthetic hair?

Dermatologists do recommend topical minoxidil off-label for traction alopecia when the follicle is still intact and not scarred. It's the only topical with FDA clearance for hair regrowth, based on studies primarily in androgenetic alopecia. It takes at least 4 months of consistent daily use to assess results. It won't work on scarred follicles, so timing matters. Discuss it with a dermatologist rather than self-diagnosing severity.

How often should you take breaks between protective styles to protect your edges?

A commonly cited guideline is 4 to 6 weeks between installs, though this isn't based on a single controlled study. The logic is follicular recovery time: constant tension without rest periods allows inflammation to accumulate. For women with a history of traction alopecia, longer breaks (6 to 8 weeks) make sense. During the break, focus on moisture, gentle handling, and scalp health before reinstalling.

Can edge thinning from synthetic hair happen in just weeks?

Yes. Follicular inflammation from high-tension styles can begin within days of installation. Visible thinning sometimes appears in as little as 2 to 4 weeks with very tight installs, especially if styles are overlapping without rest periods. The hairline's follicles are finer and more vulnerable than the rest of the scalp, so they respond to tension faster. Pain or tightness in the first 24 to 72 hours is an early warning to take the style down or have it loosened.

Does hair grow back thinner after traction alopecia?

Sometimes. After one mild episode, most people recover to close to their original density. But repeated episodes on the same area of the hairline reduce the chances of full recovery each time, because each cycle of tension and partial healing brings the follicle closer to permanent damage. This is why treating the first episode seriously, rather than waiting for it to get worse, matters more than most people realize.

What vitamins should you take for thinning edges from synthetic hair?

There's no supplement that specifically targets traction alopecia, but correcting actual deficiencies helps. Iron (check ferritin, ideally above 30 ng/mL), vitamin D, zinc, and adequate dietary protein are the most evidence-supported targets. Biotin deficiency causes hair loss, but deficiency is rare in people eating varied diets. Get bloodwork done before adding supplements; supplementing nutrients you're not deficient in generally doesn't speed up hair regrowth.

Sources

1. American Academy of Dermatology, Traction Alopecia overview: Traction alopecia is hair loss caused by prolonged or repeated tension on the hair; AAD states that if follicles are not damaged, hair regrowth is possible with avoidance of pulling hairstyles
2. Khumalo NP et al., 'Traction alopecia: how to translate study findings to counseling patients,' Dermatologic Clinics, 2014: Follicular papules and the fringe sign are early clinical markers of traction alopecia in the reversible stage
3. NIH National Library of Medicine, MedlinePlus, Hair Loss: Human hair grows approximately 0.5 inches (1.25 cm) per month on average
4. Haskin A & Aguh C, 'All hairstyles are not created equal: What the dermatologist needs to know about black hairstyling practices and the risk of traction alopecia,' Journal of the American Academy of Dermatology, 2016: Traction alopecia was present in 31.7% of women of African descent surveyed, making it one of the most prevalent forms of hair loss in this population
5. FDA, Minoxidil Drug Information: Topical minoxidil 2% and 5% are FDA-cleared for hair regrowth; used off-label by dermatologists for traction alopecia with intact follicles
6. Koyama T et al., 'Standardized Scalp Massage Results in Increased Hair Thickness by Inducing Stretching Forces to Dermal Papilla Cells in the Subcutaneous Tissue,' Eplasty, 2016: Standardized scalp massage (4 minutes daily) over 24 weeks increased hair thickness, with researchers suggesting mechanical stimulation of dermal papilla cells as the mechanism
7. Trost LB, Bergfeld WF & Calogeras E, 'The diagnosis and treatment of iron deficiency and its potential relationship to hair loss,' Journal of the American Academy of Dermatology, 2006: Serum ferritin below 30 ng/mL is associated with hair shedding; iron deficiency is among the most common nutritional causes of hair loss in women
8. Samrao A et al., 'Traction alopecia,' International Journal of Dermatology, 2019: Early-stage traction alopecia is usually reversible but chronic and severe traction may lead to permanent follicular damage via fibrous tract formation visible on scalp biopsy
9. NIH Office of Dietary Supplements, Iron Fact Sheet for Health Professionals: Iron is involved in DNA synthesis and rapidly dividing cells including follicular cells are among the first affected by iron deficiency
10. NIH Office of Dietary Supplements, Biotin Fact Sheet for Health Professionals: Biotin deficiency causes hair loss, but true deficiency is rare in people eating a varied diet; high-dose biotin can interfere with thyroid and other laboratory tests
11. USDA National Agricultural Library, Dietary Reference Intakes: The general adult protein RDA is 0.8 grams per kilogram of body weight; inadequate protein intake can slow hair recovery
12. Vañó-Galván S et al., 'Frontal fibrosing alopecia,' British Journal of Dermatology, 2014 review: Frontal fibrosing alopecia is a distinct scarring alopecia with autoimmune features that can be clinically confused with traction alopecia; it requires different treatment and worsens without medical management
13. HRSA, Find a Health Center: HRSA-funded federally qualified health centers provide primary care and referral services on a sliding fee scale for patients with limited access to specialty care
14. Vieira C et al., 'Effect of ricinoleic acid in acute and subchronic experimental models of inflammation,' Mediators of Inflammation, 2000: Ricinoleic acid, the main fatty acid in castor oil, demonstrated anti-inflammatory properties in laboratory studies
15. Oh JY et al., 'Peppermint oil promotes hair growth without toxic signs,' Toxicological Research, 2014: In a mouse study, topical peppermint oil outperformed minoxidil in increasing hair count and follicle depth; no human clinical trial has replicated this finding