Finasteride belongs to a group of medications known as 5 alpha-reductase inhibitors. It is used to treat male pattern baldness by preventing the enzyme 5 alpha-reductase from converting testosterone to its active form in the body (dihydrotestosterone or DHT).

DHT plays a major role in inherited male pattern baldness (androgenic alopecia), and by preventing its production finasteride can stimulate hair growth in many men with mild-to-moderate inherited male pattern baldness. The medication usually starts to work within 3 months of beginning treatment. The effectiveness of the medication varies – for most men, it prevents further hair loss and promotes some growth of new hair. In general, however, it will not be possible to grow back all the hair that has been lost. The new hair will stay for only one year after the medication has been stopped.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

The recommended dose of finasteride for male pattern baldness is 1 mg daily taken at the same time each day, with or without food. It is important that this medication be taken on a regular basis for it to be effective.

Many things can affect the dose of a medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important that this medication be taken exactly as prescribed by your doctor. If you miss a dose, skip the missed dose and continue with your regular schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature, protect it from light and moisture, and keep it out of the reach of children. Women who are or may become pregnant should not handle crushed or broken tablets.

Each tan-coloured, 8-sided, biconvex, film-coated tablet with "1" debossed on one side and "SZ" on the other contains 1 mg of finasteride. Nonmedicinal ingredients: lactose monohydrate, sodium starch glycolate, corn starch, magnesium stearate, collodial silicion dioxide, docusate sodium benzoate, hydroxypropyl methylcellulose, polyethylene glycol (PEG 6000), titanium dioxide, and iron oxide red (E172).

Do not take finasteride (for male pattern baldness) if you:

• are allergic to finasteride or any ingredients of the medication
• are a child
• are a woman

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent. The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• decreased amount of ejaculate (i.e., semen)
• decreased interest in sex
• erectile dysfunction (impotence)

Although most of these side effects listed below don't happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• blood in semen
• breast enlargement, tenderness, lumps, or nipple discharge
• continued ejaculation problems after stopping the medication
• decreased interest in sexual activity continuing after stopping the medication
• decreased sexual ability continuing after stopping the medication
• infertility or poor quality of semen
• muscle pain or weakness
• signs of depression (e.g., poor concentration, changes in weight, changes in sleep, decreased interest in activities, thoughts of suicide)
• pain in the testicles

Stop taking the medication and seek immediate medical attention if any of the following occur:

• signs of an allergic reaction (e.g., skin rash, itchiness, hives, swelling of the lips, tongue, throat or face)
• thoughts of suicide or self-harm

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Breast cancer: Male breast cancer has been reported in a small number of people taking finasteride. It is not known with certainty whether finasteride can cause breast cancer, but this possibility cannot be ruled out at this time. If you notice any changes in your breasts, such as breast enlargement, pain, tenderness, lumps, or nipple discharge, contact your doctor as soon as possible.

Prostate cancer: Finasteride may be linked with an increased risk of developing a rare type of cancer called high-grade prostate cancer. The risk of this cancer while taking this medication is still considered very small. Note that finasteride (for male pattern baldness) is not approved to treat prostate cancer. If you have any concerns about your medication, talk to your health care provider.

Liver function: Finasteride is broken down by the liver. This medication should be used with caution by people with impaired liver function. If you have liver disease or reduced liver function, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Pregnancy and birth defects: When absorbed into the system of a pregnant woman, finasteride may cause abnormalities of the genitals in a male baby. Crushed or broken finasteride tablets should not be handled by women who are or may become pregnant because finasteride may be absorbed into the system through the skin.

Children: Finasteride should not be used by children.

Seniors: The use of finasteride has not been studied in men over the age of 65 years with male pattern hair loss.

Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications that you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. In many cases, interactions are intended or are managed by close monitoring. Speak to your doctor about how any drug interactions are being managed or should be managed.