Finasteride and minoxidil for hair loss: what the evidence says

Minoxidil is applied to the scalp as a solution or foam. It is thought to prolong the growth phase of hair follicles and increase blood flow. In trials, a proportion of users have regrowth or slower loss. It takes months to see an effect, and an early shedding phase can occur. Side effects include scalp irritation and unwanted facial hair, and rarely dizziness or heart symptoms if absorbed. Oral minoxidil at low doses is used off-label by some specialists, with its own risks, and should only be used under medical supervision.

Finasteride blocks conversion of testosterone to dihydrotestosterone, the hormone that shrinks susceptible follicles. In men it slows loss and promotes regrowth in many. It is a prescription medicine, taken daily as a tablet. Side effects may include reduced sexual desire, erectile problems and breast tenderness. Some men report persistent symptoms after stopping, and reports of depression and suicidal thoughts have led the MHRA to advise that patients are informed and monitored. Anyone with low mood or thoughts of self-harm should seek urgent medical advice.

• Your goals and what results are realistic.

• Your history of mood problems, sexual dysfunction and prostate or liver conditions.

• Whether you are or may become a father or are planning a family.

• How long you will try treatment before judging it.

• What to do if you notice side effects.

• The impact on PSA tests, since finasteride lowers PSA levels and must be accounted for.

Finasteride is not licensed for women and must not be handled or taken by women who are or may become pregnant, because of risks to a male foetus. Topical minoxidil is licensed for women in a lower strength. Other options for women include treating underlying causes such as iron deficiency or thyroid disease, anti-androgen medicines under specialist care and cosmetic measures.

Platelet-rich plasma injections, low-level light devices, microneedling and supplements are offered widely. Evidence is limited or mixed, and quality of studies varies. Marketing claims often exceed evidence. Discuss these with a clinician before spending significant sums, and ask for evidence in the form of independent trials.

Finasteride is a prescription-only medicine in the UK and should be obtained through a registered prescriber and pharmacy. Products sold without prescription online may be counterfeit or contain different ingredients. Check registration and read the patient information leaflet. Report side effects through the Yellow Card scheme.

For most people, the realistic aim is to slow loss and, for some, to thicken existing hair, not to restore a teenage hairline. Results are usually judged by comparing photographs taken in the same light and position at the start and after six to twelve months. Treatment works only while it is used, so consider whether you are prepared to continue and for how long. If expectations and evidence do not match, other options, such as styling, fibres or a wig, may feel better.