Do probiotics help hair growth? What the research does and doesn't show

The evidence does not support probiotics as a way to grow hair. One 16-week trial in 115 adults with pattern hair loss found fewer resting-phase hairs with a three-strain mixture but no change in most other hair measures, and a pooled review found no significant change in hair count. The trials are few, small and use different products.

What the evidence doesn't support

• Probiotics regrowing hair or reversing hair loss. The pooled hair-count result was not statistically significant (SMD 0.32, 95% CI -0.10 to 0.75).
• Results from one strain applying to another. The one human trial we verified tested a specific three-strain Lactiplantibacillus mixture.
• Animal findings applying to people. The pooled review combined clinical and preclinical studies, and the clearest effects on follicle number were in animals.
• A gut-hair link as a proven mechanism. It is a hypothesis the authors discuss, not something these trials established.

What the trials found

A randomized trial in androgenic alopecia

A double-blind, parallel-group trial enrolled 136 adults aged 18 to 65 with androgenic alopecia (62 men, 74 women); 115 completed 16 weeks (57 on a mixture of three Lactiplantibacillus strains, 58 on placebo). The probiotic group had fewer telogen (resting-phase) hairs and the placebo group's hair thickness fell; the remaining measures, including hair density and length, did not change significantly. Some company employees took part in the study, and the abstract does not give the dose. The authors noted the limitations of the study.

A pooled review of trials and animal studies

A 2024 systematic review and meta-analysis combined eight randomized clinical trials and preclinical studies. Hair count did not change significantly (SMD 0.32), while hair thickness did (SMD 0.92, 95% CI 0.47 to 1.36). Preclinical studies showed more hair follicles. For dandruff, adherent dandruff did not change significantly (OR 1.31, 95% CI 0.13 to 13.65), while free dandruff did (OR 5.39, 95% CI 1.50 to 19.43). Heterogeneity was high for several outcomes, and strains and doses varied.

Questions people ask

Do probiotics help hair growth?

Not reliably, on the evidence we verified. One trial found fewer resting-phase hairs with one mixture and a review found no significant change in hair count. We found no verified trial of an ordinary multi-strain supplement for hair.

Do probiotics help with dandruff?

The review above found one dandruff outcome improved and another did not, from two studies. That is too little to rely on.

Is there a probiotic for hair loss?

Not one with confirmed results. Hair loss has many causes, including thyroid problems, iron deficiency and medicines. See a doctor or dermatologist for sudden or patchy loss. For how probiotic evidence works in general, see probiotics benefits: what the research does and doesn't show and probiotics and skin conditions.

When to talk to a doctor

A probiotic is not a treatment for hair loss. Sudden hair loss, bald patches, a scaly or sore scalp, or loss with fatigue or weight change should be assessed by a doctor. If you are pregnant or nursing, have a weakened immune system or take prescription medicine, ask a doctor or pharmacist before starting any probiotic.