Worked in Rats what about people?
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Skin and hair

The stuff with real trials sits on a pharmacy shelf. The trendy stuff has almost no human testing.

The short version

Daily sunscreen and tretinoin have real trials behind them for skin. Minoxidil and finasteride beat placebo for hair, with modest gains. Collagen only looked good in company-funded studies. We found no human study of the injectable "glow" blends.

What has proof

A

Daily sunscreen

A trial followed 903 adults for 4.5 years. People told to use sunscreen every day showed no detectable increase in skin aging, 24% less than people who used it when they felt like it.

the skin product with the best trial on this page

A

Tretinoin (prescription cream)

A review of 8 trials in 1,361 people found it improved fine and coarse sun wrinkles compared with plain cream.

A

Minoxidil and finasteride for hair

Twelve trials tested finasteride in 3,927 men. Hair count was about 9% above placebo within a year, and about 24% after two. About one extra man in six noticed an improvement. Erection problems roughly doubled, about one extra case per 82 men. Minoxidil in women: 157 of 593 reported moderate or better regrowth, against 77 of 555 on placebo.

real but modest: more hairs, not a full head

B

Collagen for skin

A review of 23 trials in 1,474 people found better hydration, elasticity and wrinkles overall. But the trials not funded by companies found no effect, and neither did the best-run trials. The authors concluded there is no clinical evidence to support it for skin aging.

only worked in company-funded studies

C

Copper peptide cream (GHK-Cu)

Few careful tests have been done in people. In those, it did not beat the comparison cream. A 13-person trial after laser treatment found no difference. A trial in 86 people with leg ulcers found it no better than placebo. Most of the good results come from lab and animal work.

worked in the lab

Gym lore, checked

Gym lore is what people say, not what we recommend. Each one is followed by what studies in people show. Stories are real experiences. They are not proof.

"the GLOW and KLOW stacks give you glowing skin"

Never tested in people. GLOW is BPC-157, TB-500 and GHK-Cu in one shot. KLOW adds a fourth, KPV. No study of either blend in people has been published. We found no human study of KPV for any condition, on PubMed or in the trial registry.

No human study of the blends

"Melanotan II is a safe tan and protects you from skin cancer"

We found nothing that shows protection. Doctors have reported harm. Case reports describe melanomas in young users, including a 20-year-old and a 22-year-old, plus new and darkening moles. A 2026 review of 68 studies also lists muscle breakdown, a blocked blood supply to the kidney, and long, painful erections. Case reports cannot prove the drug was the cause. Nothing we found shows it protects against skin cancer.

a new or changing mole needs a doctor, not a forum

Melanoma case reportsNo proof of protection

"glutathione shots brighten your skin"

The one fair test did not clearly work, and people got sick in 2026. A 2024 review found one placebo-controlled trial of the drip: 6 of 16 people responded, against 3 on placebo. That is not a clear difference. In August 2026 the FDA reported at least 30 patients who reacted to glutathione drips made from supplement-grade ingredient that is not meant for injection.

FDA warning, Aug 2026One small trial

"biotin grows hair"

Not if your levels are normal. A 2024 review found three studies. The best one, with a placebo group, showed no difference in hair growth. The reported successes were all in people with an underlying problem. The FDA also warns that biotin can make some blood tests read wrong, including a test used to spot heart attacks.

No benefit in the placebo trialCan skew lab tests

"copper peptides regrow hair"

Mixes showed more hairs in small studies. Copper peptide alone is untested. A 2026 review found 14 small trials of peptide blends. One placebo-controlled trial in 45 men used a blend containing a GHK peptide and found more hairs after 6 months, but no change in thickness. We found no trial of copper peptide by itself for scalp hair.

Small trials of blendsAlone: not tested

What we don't know

  • Whether any injected "skin peptide" does anything in people.
  • The long-term safety of tanning peptides.
  • What is actually in a vial or drip that did not come from a pharmacy.

Sources

  1. Daily sunscreen and skin aging, trial in 903 adults. Annals of Internal Medicine, 2013. Journal page
  2. Tretinoin for sun-aged skin, review of 8 trials. Dermatology Practical and Conceptual, 2025. Journal page
  3. Finasteride for male hair loss, review of 12 trials. Archives of Dermatology, 2010. Journal page
  4. Treatments for female pattern hair loss, Cochrane review, 2016. Journal page
  5. Hair loss treatments compared. Journal of the American Academy of Dermatology, 2017. Journal page
  6. Collagen and skin aging, review of 23 trials by funding source. American Journal of Medicine, 2025. Journal page
  7. Copper peptide after laser resurfacing, trial. Archives of Facial Plastic Surgery, 2006. Journal page
  8. Copper peptide cream for leg ulcers, trial. Journal of Vascular Surgery, 1992. Journal page
  9. GHK-Cu, 2026 review. Pharmaceutics. Journal page
  10. Melanoma after Melanotan II and sunbeds, case report. Dermatology, 2014. Journal page
  11. Mouth melanoma in a nasal tanning spray user, case report. International Journal of Oral and Maxillofacial Surgery, 2025. Journal page
  12. Melanotan harms, 2026 systematic review. PubMed 41890775. PubMed
  13. Glutathione for skin lightening, 2024 systematic review. International Journal of Dermatology. Journal page
  14. FDA on supplement-grade glutathione in injectables, August 27, 2026. FDA
  15. Biotin for hair, 2024 review. PubMed 39148962. PubMed
  16. Biotin for hair and nails, review of case reports. Skin Appendage Disorders, 2017. Journal page
  17. FDA on biotin and troponin lab tests. FDA
  18. Peptides for hair, 2026 systematic review. Journal of Drugs in Dermatology. Journal page
  19. GHK peptide blend for hair, trial in 45 men. Annals of Dermatology, 2016. Journal page

Studies found on PubMed. Last checked November 12, 2026. Information only. Not medical advice.