Health, fitness and the supplement aisle. An independent South African desk.
Vitamins and minerals · Answer
Biotin helps hair growth only if you are deficient, which is rare. Evidence in healthy people is weak, limited to case reports and small studies. Large supplement doses can also distort blood tests, including thyroid hormones and troponin used to diagnose heart attacks. In South Africa, tell your doctor and the laboratory if you take biotin before any blood test.
Biotin (vitamin B7) is essential for energy metabolism, and severe deficiency can cause hair thinning and a scaly rash. That is why it is sold for hair, skin and nails. But the NIH says claims for hair, skin and nail benefits in healthy people are supported, at best, by only a few case reports and small studies. The hair-specific reports involve children with uncombable hair syndrome, not adults with ordinary hair loss. Evidence level for healthy adults: weak.
The NIH adequate intake is 30 µg a day for adults (35 µg while breastfeeding). Most people meet this through eggs, nuts, seeds, meat and some vegetables. True deficiency is rare and usually linked to genetic disorders such as biotinidase deficiency, or prolonged raw egg white intake, and sometimes to certain medicines. Hair and nail products typically supply many times the adequate intake, which cannot be shown to help someone who already has enough.
High doses can interfere with biotin-streptavidin laboratory assays, which are used for many hormones and other tests. Per the NIH and the FDA:
| Test affected | What can happen |
|---|---|
| Thyroid tests | Falsely suggest Graves' disease or hyperthyroidism (case reports at 10 to 300 mg a day); a single 10 mg dose interfered with tests taken within 24 hours |
| Troponin | Falsely low result; the FDA reported a death in a patient on high-dose biotin |
| Other hormone and vitamin assays | False highs or lows, depending on the test design |
This matters for South Africans having routine bloods through a private lab or state clinic. Tell the doctor, and ask how long to pause before a test. Do not self-stop prescribed treatment.
Before spending money on biotin, consider treatable causes that a doctor can check:
Persistent or patchy hair loss, scalp pain, or sudden shedding should be assessed by a doctor or dermatologist.
Collagen peptides are also marketed for hair and nails, with mixed evidence. See does collagen help hair and nails? for details. Being honest about the evidence helps avoid spending on products that are unlikely to change outcomes.
Keep the dose near the adequate intake (a multivitamin often covers it), avoid megadoses, tell your doctor and lab, and stop if rash, nausea or other symptoms appear. Pregnant and breastfeeding women, under-18s and anyone with a medical condition should ask a healthcare professional first. Read can you take too many vitamins? and do multivitamins work? too.
Educational information, not medical advice. Speak to a doctor, pharmacist or registered dietitian before using supplements if you are pregnant or breastfeeding, under 18, taking medication, or living with kidney, liver or heart disease. Prices were observed in October 2026 and are not offers.