What are the side effects of Propecia?

Propecia is a prescription medicine used in the treatment of male pattern baldness (androgenic alopecia), in men aged 18 and over, to help increase hair growth on the scalp and help prevent further hair loss. Pattern baldness, also known as pattern hair loss, affects about half of men over the age of 50.

What is Propecia?

Propecia is the branded version of generic finasteride. Propecia comes in tablet form and, for hair loss, it works by lowering the level of dihydrotestosterone (DHT) – a male sex hormone – in your bloodstream. Sensitivity to DHT can prevent scalp hair follicles from producing strong, healthy hair in men with male pattern hair loss. Women should not use Propecia.

You'll probably need to take Propecia for between three to six months before seeing any results. If you stop taking the medicine, hair loss will revert to pre-treatment levels within nine to 12 months.

Finasteride and Propecia can be accessed through the Boots Hair Loss Online Clinic. You’ll only be offered treatment through the clinic after completing an online consultation (subject to availability and clinician approval. Charges apply).

You can also ask your GP for a private prescription.

Can anyone take Propecia?

Propecia is used in the treatment of male pattern hair loss in men aged 18 and over. The active ingredient finasteride has not been licensed as a treatment for pattern baldness in women because it can cause genital abnormalities in male foetuses. Pregnant women are also advised against handling finasteride because of the risk of absorbing it through the skin. Finasteride has also not been licensed for use in children.

Because small amounts of finasteride can be passed through semen and endanger the foetus, men who are taking Propecia or generic finasteride are advised to use a reliable method of contraception to avoid pregnancy. Propecia and generic finasteride aren’t suitable for men with partners who are pregnant or trying to conceive.

Does Propecia have side effects?

As with all medicines, there can be potential side effects to taking Propecia. While not everyone will experience them, there is a risk of the following side effects:

Sexual problems

This is reported as an uncommon side effect which may affect up to one in 100 people, and can include:

• Erectile dysfunction (the inability to get, or maintain, an erection)

• Loss of sex drive (libido)

• Reduced volume of semen

The risk of these side effects is likely to increase with prolonged use of the medicine. In rare cases, one or more of these side effects has been reported even after treatment has been stopped.

Breast abnormalities

A raised incidence of breast cancer has been noted in men using finasteride-based medicines.

If you experience any of the following when taking Propecia, stop taking the medicine and see your GP immediately:

• Nipple discharge

• Sore or swollen breasts

• Breast nodules (small lumps)

Mental health problems

Depression, anxiety and suicidal thoughts have been reported by some men using Propecia. If you experience changes in your mood and mental health while taking Propecia, stop taking the medicine and see your GP immediately.

Allergic reaction

A mild allergic reaction to finasteride has been seen in a small number of patients. This might include skin rash, itching (pruritus) and hives (urticaria). If you have any of these symptoms while taking Propecia, see your GP.

Although rare, extreme allergic reactions (hypersensitivity) have also been reported. Symptoms might include swelling of the face and lips, and impaired breathing. This is a medical emergency. If you experience these symptoms, visit an A&E department immediately, or call 999 for an ambulance.

For the full list of side effects read the patient information leaflet.

Next steps

• If you experience breast abnormalities when taking Propecia, stop taking Propecia and see your GP immediately

• If you experience changes in your mood and mental health while taking Propecia, stop taking Propecia and speak to your GP

• Speak to your pharmacist or GP if you experience side effects whilst taking Propecia