Hair Growth Supplements & Scalp Oils

Pregnancy

NIH ODS lists a biotin adequate intake of 30 mcg per day during pregnancy and says deficiency is rare. ODS says claims that biotin supplements promote hair health are supported only by case reports in children with uncombable hair syndrome, a rare hair-shaft disorder; these reports do not address routine pregnancy-related shedding in adults. ODS also notes that prenatal formulas vary and that some contain botanicals not thoroughly studied in pregnant women. A 2026 randomized trial compared prenatal multivitamins with 150 mcg versus 30 mcg biotin for 24 weeks in 80 pregnant participants; 62 completed. It measured maternal and cord blood biomarkers, not hair growth, and three authors listed Ritual affiliations; full funding and conflict disclosures were not available in the PubMed record. NCCIH advises against ashwagandha during pregnancy. A 2026 open-label trial evaluated one standardized ashwagandha root extract in 70 second-trimester participants, with 63 completing; its outcomes were blood counts, stress, sleep, and laboratory markers, not hair loss or birth outcomes. The extract was supplied by Ixoreal, which the authors said had no role; the paper reported no funding. Maas et al. advise against saw palmetto during pregnancy or lactation because of its anti-androgenic activity and the lack of data for pregnant or lactating women. Health Canada's monograph gives a do-not-use statement for oral saw palmetto in adult females. EMA's rosemary-leaf warning applies to medicinal products made from dried leaf and excludes cosmetic products and food supplements, so it does not establish a warning for rosemary scalp oil.

Breastfeeding

CDC says some breastfeeding mothers may benefit from a multivitamin based on diet and higher nutrient needs; this guidance addresses nutrition rather than hair growth. NIH ODS lists 35 mcg per day as the adequate intake for biotin during lactation and says hair-benefit reports are limited to children with rare disorders. LactMed reports that no clinical trials have demonstrated peppermint-related suppression of milk production. It describes cell and animal findings and milk measurements after oral exposure; those findings do not answer whether topical scalp use affects milk supply. NCCIH advises against ashwagandha while breastfeeding. NHS SPS advises against herbal products because information about transfer into milk is insufficient. Health Canada's saw-palmetto monograph says not to use oral saw palmetto during breastfeeding for adult females; this is not a finding about topical scalp products. Maas et al. report that lactation data for saw palmetto are absent and do not recommend its use during lactation.

What was tested

Panahi et al. (2015) randomized 100 patients with androgenetic alopecia, 50 per group, to rosemary oil or 2% minoxidil for six months. Hair counts increased in both groups by month six, with no significant between-group difference; the study had no placebo arm and did not assess pregnancy-related shedding. Zhou et al. (2026) reviewed randomized supplement trials in adults with androgenetic alopecia and explicitly excluded studies involving pregnant women. Its abstract reports 19 trials and 1,658 participants, while other full-text sections refer to 20 trials; the count is internally inconsistent. The review reports some ingredient-specific hair-density signals, substantial heterogeneity, and moderate or low certainty depending on the outcome. A 2026 double-blind saw-palmetto trial assigned 60 adults with self-perceived thinning to a proprietary extract (40 participants) or placebo (20) for 180 days. Pregnancy and lactation were exclusion criteria, and the trial did not include clinical chemistry panels. A separate 90-day report with the same author and trial registration is an interim report from that same study, not a separate trial.