Caffeine Shampoo for Thinning Hair: What the Evidence Shows for Women

Caffeine shampoos and leave-in tonics are marketed to women with thinning hair, often with claims about energizing follicles. Here is what the research shows.

The lab studies

In a 2014 study, researchers grew human scalp hair follicles from men and women in lab dishes. Caffeine lengthened hair shafts and kept follicles in the growth phase longer, and follicles from women responded more strongly than those from men.¹

That’s interesting, but follicles in a dish aren’t a scalp on a person. Lab results don’t show how much caffeine reaches follicles from a shampoo that’s rinsed off after a minute or two.

The clinical trial

The main trial compared a 0.2% caffeine leave-in liquid with 5% minoxidil in 210 men with pattern hair loss for 6 months.²

• The proportion of hairs in the growth phase improved by about 11.7% with minoxidil and 10.6% with caffeine, and the authors concluded caffeine was not inferior.²
• The study was open-label: participants and examiners knew which product was used. The authors listed this as a limitation that could cause bias.²
• One author was an employee of the company that sponsored the study.²
• It tested a leave-in liquid used twice daily, not a shampoo, and it included only men.²

How this compares with proven options

The trial authors noted that minoxidil solution is an approved treatment for pattern hair loss in women.² Our guide to topical minoxidil explains how it’s used. Other popular options with limited evidence include rosemary oil and scalp massagers.

If you want to try caffeine

1. Leave-in products match what was studied better than shampoos.
2. Keep using proven treatments if your clinician recommended them.
3. Take photos monthly in the same light, and judge after several months.
4. Stop if your scalp gets irritated.

Get the cause checked

Thinning can come from pattern hair loss, shedding after illness or stress, thyroid problems, low iron or medicines. Our article on why hair thins explains the causes a clinician may check.

Try: “My part is widening and I’ve been using a caffeine shampoo. Should we check iron and thyroid, and would minoxidil be a better option for me?”

Hair, Everywhere includes a Hair Check, a monthly Hair Log and a visit script. Use them to track photos, shedding and products over time. See the book.