Melatonin Does Not Cause Hair Color Changes from Black to Brown
Melatonin tablets do not cause hair to change color from black to brown. There is no evidence in medical literature linking oral melatonin supplementation to changes in human hair pigmentation.
Evidence Against Hair Color Changes
The available evidence does not support melatonin causing hair color alterations in humans:
A comprehensive review of drug-induced hair color changes identified chloroquine and cancer chemotherapeutic agents as having the best evidence for causing such changes, but melatonin was not mentioned among implicated medications 1.
While melatonin has been studied extensively for its effects on hair growth and the hair cycle, no clinical trials or case reports have documented hair color changes as an adverse effect 2, 3.
What Melatonin Actually Does to Hair
Research shows melatonin's effects on hair are limited to growth promotion, not pigmentation changes:
Topical melatonin (0.1% solution) significantly increased anagen (growth phase) hair rate in women with androgenetic alopecia and diffuse alopecia over 6 months, but no color changes were reported 2.
Melatonin modulates hair growth cycles and may have cytoprotective effects on hair follicles through its antioxidant properties, but these mechanisms do not involve melanin pigmentation alterations 3, 4.
Animal vs. Human Hair Biology
An important distinction exists between animal and human responses:
In certain animal species (particularly those with seasonal coat changes), melatonin does influence hair pigmentation and molting as part of photoperiod-dependent environmental adaptations 4.
However, humans are classified as "nonphotoperiodic species" that do not undergo seasonal physiologic changes such as coat color alterations 5.
The melanophore pigment aggregation response to melatonin seen in amphibians (like Xenopus laevis) involves rapid melanosome movement that lightens skin color temporarily, but this mechanism does not exist in human hair follicles 6.
Common Pitfalls to Avoid
Do not confuse animal research with human effects: Studies showing melatonin's influence on coat color in sheep, goats, or other animals do not translate to human hair pigmentation 4.
Consider other causes: If hair color change is occurring, investigate other medications (particularly chloroquine, cancer chemotherapy agents), nutritional deficiencies, or natural aging processes 1.
Recognize normal variation: Hair color can naturally lighten due to sun exposure, aging, or oxidative stress unrelated to melatonin use.
Safety Profile of Melatonin
The established adverse effects of melatonin are well-documented and do not include hair color changes:
The most frequently reported adverse events are headache (0.74%), dizziness (0.74%), and somnolence (1.66%) 7.
Higher doses (above 3-6 mg) may cause morning grogginess, gastrointestinal upset, and receptor desensitization, but not pigmentation changes 7.
Long-term safety data up to 24 months in pediatric populations and several months in adults show no reports of hair color alterations 7.