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FAQ10 min read

Can Peptides Cause Hair Loss?

The fear is understandable. You start a new peptide protocol — maybe for recovery, growth hormone optimization, or metabolic health — and a few weeks later, you notice more hair in the shower drain. Was it the peptide? A coincidence? Something else entirely?

The fear is understandable. You start a new peptide protocol — maybe for recovery, growth hormone optimization, or metabolic health — and a few weeks later, you notice more hair in the shower drain. Was it the peptide? A coincidence? Something else entirely?

The relationship between peptides and hair is more complicated than a simple yes-or-no answer. Some peptides may theoretically accelerate hair loss in genetically predisposed individuals. Others are actively being researched as treatments for hair loss. And some have no meaningful effect on hair at all.

Here's what the science actually supports, separated from the anxiety-driven speculation that dominates online forums.

Table of Contents

How Hair Loss Actually Works

Before blaming any peptide, it helps to understand the basics.

Hair grows in cycles. The anagen phase (active growth) lasts 2-7 years. The catagen phase (transition) lasts 2-3 weeks. The telogen phase (rest) lasts about 3 months, after which the hair falls out and a new one starts growing. At any given time, about 85-90% of your hair is in anagen and 10-15% is in telogen [1].

Androgenetic alopecia (pattern hair loss) — the most common type — is driven by dihydrotestosterone (DHT), a potent androgen converted from testosterone by the enzyme 5-alpha reductase. DHT binds to androgen receptors in genetically sensitive hair follicles, triggering a process called follicular miniaturization. Over successive growth cycles, the follicle produces thinner, shorter, less pigmented hair until it eventually stops producing visible hair altogether [2].

Telogen effluvium is temporary, diffuse hair shedding triggered by a physiological stress — illness, surgery, dramatic weight loss, hormonal changes, medication changes, or nutritional deficiency. It pushes a larger-than-normal percentage of hairs into the telogen (resting) phase simultaneously, resulting in noticeable shedding 2-4 months after the trigger.

These two mechanisms explain the vast majority of hair loss that people attribute to peptides.

Growth Hormone Peptides and the IGF-1/DHT Connection

Growth hormone secretagogues like CJC-1295, ipamorelin, GHRP-2, GHRP-6, and MK-677 work by stimulating your pituitary gland to release more growth hormone (GH). GH then stimulates the liver to produce insulin-like growth factor 1 (IGF-1).

Here's where it gets nuanced. IGF-1 plays a dual role in hair biology:

In the scalp (local tissue): IGF-1 is a critical growth signal for hair follicles. Dermal papilla cells — the master regulators of the hair growth cycle — produce IGF-1, which promotes the anagen (growth) phase. DHT inhibits IGF-1 production in dermal papillae, which is one mechanism by which it causes hair loss [3]. So local IGF-1 in the scalp is protective.

In the blood (systemic): Elevated circulating IGF-1 has a more complex relationship with hair. Some researchers have proposed that high serum IGF-1 may stimulate 5-alpha reductase activity, increasing DHT conversion — which could theoretically accelerate pattern hair loss in genetically predisposed individuals [4]. However, this mechanism remains debated and has not been definitively proven in clinical studies.

What this means practically: If you're using growth hormone secretagogues and you carry the genetic predisposition for androgenetic alopecia (male or female pattern hair loss), there's a theoretical risk that elevated IGF-1 could slightly accelerate the process. This isn't a certainty — many people use GH peptides without any hair changes. But it's a variable worth monitoring, especially if you have a family history of hair loss.

People with no genetic predisposition to pattern hair loss are extremely unlikely to experience hair loss from GH peptides.

GLP-1 Drugs and Hair Loss Reports

Semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro, Zepbound) users sometimes report hair shedding. This has generated significant online anxiety. But the mechanism is almost certainly not a direct drug effect on hair follicles.

In the STEP 1 trial for semaglutide, alopecia was reported as an adverse event in approximately 3% of the semaglutide group versus 1% of the placebo group [5]. For tirzepatide in the SURMOUNT-1 trial, hair loss rates were similar — around 4-6% in treatment groups.

The likely explanation: rapid weight loss triggers telogen effluvium. Participants in these trials lost 15-20% of their body weight over 68 weeks. Rapid caloric restriction and significant weight loss are well-established triggers for telogen effluvium, regardless of how the weight loss occurs. Bariatric surgery patients experience similar hair shedding rates [6].

Supporting this interpretation:

  • Hair loss rates correlate with the amount of weight lost, not with the specific drug used
  • The pattern is diffuse shedding (classic telogen effluvium), not androgenetic patterning
  • Hair shedding typically begins 2-4 months after the period of most rapid weight loss
  • It's self-limiting — hair typically regrows once weight stabilizes

Ensuring adequate protein intake (at least 60-80g daily), iron, zinc, biotin, and vitamin D during GLP-1 therapy can help mitigate this effect.

BPC-157 and Hair: What the Data Shows

BPC-157 has not been associated with hair loss in any published research. In fact, its mechanisms of action — VEGF stimulation, angiogenesis, growth factor upregulation — are theoretically favorable for hair follicle health, since blood supply to the follicle is important for maintaining the anagen phase.

No clinical studies have specifically examined BPC-157's effects on hair growth or loss. The peptide's primary research focus has been on gastrointestinal and musculoskeletal healing. If you're using BPC-157 and experiencing hair loss, other factors (stress, nutritional status, hormonal changes, other medications) are more likely explanations.

Melanotan II and Hair Changes

Melanotan II activates melanocortin receptors, primarily MC1R (for pigmentation) and MC4R (for appetite and sexual function). Some users report changes in hair color (darkening) and, less commonly, changes in hair texture or shedding.

MC1R activation can affect melanocyte function in hair follicles, which explains the color changes. The relationship between melanocortin signaling and the hair growth cycle is less clear, though some research suggests MC1R may play a role in hair follicle cycling [7].

Melanotan II carries its own set of safety concerns — including unregulated production, nevi (mole) changes, and cardiovascular effects — that make hair changes a relatively minor consideration in its overall risk profile.

Peptides That May Help Hair Growth

While some peptides raise theoretical hair loss concerns, others are actively being researched as hair loss treatments:

GHK-Cu (Copper Peptide)

GHK-Cu has some of the most promising data for hair. It stimulates blood vessel formation, activates hair follicle cells, and has been shown to increase the size of hair follicles. One study reported a 27% increase in hair density after six months of topical copper peptide use [8]. GHK-Cu may also reduce DHT levels locally, addressing the primary driver of androgenetic alopecia.

Thymosin Beta-4 (TB-500)

TB-500 promotes cell migration and plays a role in stem cell mobilization. In animal studies, thymosin beta-4 stimulated hair growth by activating dormant hair follicle stem cells and promoting the transition from telogen to anagen [9]. Its effects on human hair loss haven't been studied in clinical trials.

Acetyl Tetrapeptide-3 (in Capixyl)

This is one of the most commercially successful peptide-based hair loss treatments. Combined with red clover extract (a natural DHT inhibitor), acetyl tetrapeptide-3 has shown a 17% increase in hair diameter and 67% improvement in hair growth activity in clinical trials [10].

Biotinoyl Tripeptide-1

Used in many commercial hair care products, this peptide has been shown to reduce hair loss by 58% and increase hair density by 35% in clinical studies.

IGF-1 Mimetic Peptides

A 2025 study introduced a novel self-assembling peptide that mimics IGF-1 activity specifically at the scalp level. In androgenetic alopecia mouse models, it activated the IGF-1 receptor in dermal papilla cells, resisted DHT-induced cell death, and promoted hair regeneration more effectively than minoxidil [11].

Telogen Effluvium: The Real Culprit Behind Most "Peptide Hair Loss"

When people report hair loss after starting a peptide, telogen effluvium is almost always the more likely explanation. Here's why:

People start peptides during periods of change. They've recently:

  • Begun a new diet or caloric restriction (especially common with GLP-1 drugs)
  • Increased exercise intensity
  • Experienced illness or injury (often the reason for starting BPC-157 or TB-500)
  • Changed other medications
  • Undergone significant stress (financial investment in peptide therapy itself can be a stressor)

Any of these can independently trigger telogen effluvium. The timing correlation with starting a peptide creates a spurious association — the peptide gets blamed for a shedding event caused by something else entirely.

Telogen effluvium has a characteristic 2-4 month delay between trigger and shedding. So if you started a peptide in January and notice increased shedding in March or April, the actual trigger may have been a dietary change, illness, or stress event from November or December.

How to Assess Whether a Peptide Is Affecting Your Hair

If you're concerned about hair loss during peptide use, here's a systematic approach:

  1. Document the timeline. When did shedding start? When did you begin the peptide? What else changed around that time (diet, stress, other medications, illness)?

  2. Characterize the shedding. Is it diffuse (all over) or patterned (hairline, crown)? Diffuse shedding suggests telogen effluvium. Patterned loss suggests androgenetic alopecia, which has a genetic component that predates any peptide use.

  3. Check your nutrition. Are you getting adequate protein, iron, zinc, biotin, and vitamin D? Nutritional deficiencies are the most common correctable cause of hair shedding.

  4. Get bloodwork. Check thyroid function, iron/ferritin, vitamin D, complete blood count, and hormone panel. These can identify underlying causes unrelated to peptide use.

  5. Consider a trial discontinuation. If you strongly suspect a specific peptide, stopping it for 3-6 months and monitoring hair changes can help establish causation. Telogen effluvium typically resolves 6-12 months after removing the trigger.

  6. See a dermatologist. A dermatologist can perform a pull test, trichoscopy (scalp microscopy), and potentially a scalp biopsy to definitively diagnose the type of hair loss you're experiencing.

Frequently Asked Questions

Will MK-677 cause hair loss?

MK-677 elevates GH and IGF-1 levels. If you carry the genetic predisposition for androgenetic alopecia, sustained IGF-1 elevation could theoretically accelerate the process. However, many MK-677 users report no hair changes. The risk depends on your individual genetics. Monitoring hair quality and considering periodic cycling can help manage this risk.

Do skincare peptides affect scalp hair?

Topical skincare peptides like Matrixyl and Argireline applied to the face do not affect scalp hair. Their effects are local and don't reach systemic circulation in meaningful concentrations.

Can BPC-157 help with hair loss?

No clinical studies have tested BPC-157 specifically for hair loss. Its pro-angiogenic and growth-factor-stimulating properties are theoretically favorable for hair follicle health, but this remains speculative. See our full BPC-157 guide for details on what the research does and doesn't support.

Is hair loss from GLP-1 drugs permanent?

No. Hair shedding associated with GLP-1 drugs like semaglutide is telogen effluvium triggered by rapid weight loss. It's temporary and self-correcting. Hair typically regrows once weight stabilizes, though the process can take 6-12 months. Adequate protein and micronutrient intake during weight loss can help minimize shedding.

Should I stop my peptide if I notice hair loss?

Not necessarily. First, assess whether the hair loss is actually caused by the peptide (see the assessment framework above). Many other factors — stress, diet, hormonal changes, seasonal variation, other medications — cause hair shedding. Stopping an effective peptide therapy based on a coincidental timing correlation would be premature. Consult a dermatologist for proper evaluation.

The Bottom Line

Most peptides do not cause hair loss. The majority — including BPC-157, TB-500, skincare peptides, and anti-inflammatory peptides — have no mechanism by which they'd affect hair follicles.

Growth hormone peptides carry a theoretical risk for people genetically predisposed to pattern hair loss, through the IGF-1/DHT pathway. This risk is modest, individual-dependent, and manageable with monitoring and cycling.

GLP-1 drugs cause hair shedding through rapid weight loss (telogen effluvium), not through a direct drug effect on follicles. It's temporary.

And several peptides — notably GHK-Cu, acetyl tetrapeptide-3, and thymosin beta-4 — show real promise as hair loss treatments.

If you're losing hair and using peptides, the peptide may not be the problem. Get a proper evaluation before making changes to a protocol that's working for you in other ways.

References

  1. Paus, R., and Cotsarelis, G. "The biology of hair follicles." New England Journal of Medicine 341.7 (1999): 491-497. NEJM.

  2. Sinclair, R.D. "Male pattern androgenetic alopecia." BMJ 317.7162 (1998): 865-869. BMJ.

  3. Zhao, J., et al. "Dihydrotestosterone inhibits hair growth in mice by inhibiting insulin-like growth factor-I production in dermal papillae." Growth Hormone & IGF Research 21.5 (2011): 260-267. PubMed.

  4. Trüeb, R.M. "Molecular mechanisms of androgenetic alopecia." Experimental Gerontology 37.8-9 (2002): 981-990. PubMed.

  5. Wilding, J.P.H., et al. "Once-weekly semaglutide in adults with overweight or obesity." New England Journal of Medicine 384.11 (2021): 989-1002. NEJM.

  6. Ruiz-Tovar, J., et al. "Hair loss in females after sleeve gastrectomy." Obesity Surgery 24.6 (2014): 885-888. PubMed.

  7. Kauser, S., et al. "Human hair follicle and epidermal melanocytes exhibit striking differences in their aging profile which involves catalase." Journal of Investigative Dermatology 131.4 (2011): 979-982. PubMed.

  8. Pickart, L., et al. "Regenerative and protective actions of the GHK-Cu peptide in the light of the new gene data." International Journal of Molecular Sciences 19.7 (2018): 1987. PMC.

  9. Philp, D., et al. "Thymosin beta 4 promotes angiogenesis, wound healing, and hair follicle development." Mechanisms of Ageing and Development 125.2 (2004): 113-115. PubMed.

  10. Jindo, T., et al. "Clinical efficacy of biomimetic peptide for hair growth." Journal of Cosmetic Dermatology (2016). Various industry studies on Capixyl formulation.

  11. Zhao, H., et al. "Self-assembling peptide inspired by insulin and type 1 insulin-like growth factor for the treatment of androgenetic alopecia." Bioactive Materials (2025). ScienceDirect.