DHT and hair loss
Pattern hair loss (androgenetic alopecia) is common in both men and women. In genetically susceptible people, dihydrotestosterone (DHT) shrinks hair follicles so hair becomes progressively thinner.[1]
Finasteride reduces the conversion of testosterone to DHT and can slow or reduce this type of hair loss, but it does not treat hair loss from other causes, such as thyroid disease, iron deficiency or stress.[1]
Weighing benefit and risk
The decision to use it should weigh the benefit for hair, possible side effects and personal priorities.[1] For some people, hair matters greatly to confidence; others may choose alternatives once they know about side effects.
Understanding the numbers correctly
How common hair loss is and how often sexual side effects occur are different measures.[1] In addition, spontaneous adverse-event reports have no denominator, so they cannot directly calculate an individual's risk.
How the medicine works
Finasteride inhibits the enzyme 5-alpha reductase, which converts testosterone to DHT, so DHT levels fall.[1],[2]
Lowering DHT does not mean testosterone is depleted; testosterone usually stays the same or rises slightly.[1],[2] Dutasteride, in the same class, is used for an enlarged prostate and carries similar warnings.
What to assess
Assessment should cover[1],[2]:
- The pattern of hair loss, to confirm it is the type the medicine helps.
- The timeline: whether sexual or mood changes began after starting.
- Sexual and mood changes.
- Other causes of both hair loss and sexual problems.
Side effects and the latest warnings
MHRA warnings, 2026. The UK Medicines and Healthcare products Regulatory Agency updated its warnings on psychiatric and sexual side effects of finasteride and dutasteride.[1]
Sexual side effects. Reduced desire, erection problems or ejaculation problems may occur, and some people report persistent symptoms after stopping.[1]
Mood effects. Depression and suicidal thoughts have been reported. Users should watch their mood and ask people close to them to do the same.[1]
What to do. Review any new symptoms with the prescriber. Spontaneous reports cannot directly establish an individual's probability of harm.[1]
How we care for you at Dr. Kris Clinic
Before starting, we explain benefits and both sexual and mood side effects plainly, and check for other causes of hair loss where appropriate, in English or Thai.
If you are taking it and notice sexual or mood changes, we assess them and plan with you, including treating any sexual difficulties.
Frequently asked questions
Does finasteride lower testosterone?
No. It lowers DHT; testosterone usually stays the same or rises slightly.
Are sexual side effects common?
They occur in some people, but spontaneous reports cannot give an individual's risk. Talk to your doctor.
Will symptoms go away after stopping?
Most improve, but some people report persistent symptoms. See a doctor for assessment.
I feel depressed on finasteride. What should I do?
Stop it and contact a clinician promptly. If you have thoughts of harming yourself, seek emergency help.
Review new symptoms with the prescriber, and understand that spontaneous reports do not quantify an individual's risk.[1] Mood changes need prompt attention.
Talk to a doctor about this
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Dr. Krida Uakridathikarn (Dr. Kris)
Board-certified family physician with certificate training in clinical sexology and sexual medicine. He works at Suratthani Hospital and provides sexual health, hormone and LGBTQ+ inclusive care at Dr. Kris Clinic. Profile and CV
References
- MHRA: Updated finasteride/dutasteride psychiatric and sexual warnings (2026)
- EAU Guidelines 2026: Management of Erectile Dysfunction
- EAU Guidelines 2026: Male Hypogonadism
Keep reading
Main guide: Sexual wellbeing
Chronic Conditions and Sexual Health: Diabetes, Blood Pressure and Heart Disease
Sleep, Stress and Exercise: Foundations of Sexual Health
Weight, Hormones and Sexual Health: What You Should KnowThis article is general education, not personal medical advice or a promise of results. Diagnosis and treatment require assessment by a doctor. Content reflects the cited sources as of the update date.