OverviewDosageSide EffectsInteractionsHalf-Life

As is the case with any other medication, there may be some instances where finasteride use is not recommended or the dosage will have to be adjusted to prevent or reduce the risk of adverse interactions occurring from other drugs, medical conditions, or even food and drink.

Drug Interactions

According to the FDA, there are no significant drug interactions with finasteride. 

Please note that this list may not be complete, and other interactions with drugs not listed here may occur.

Finasteride and Minoxidil

Finasteride and minoxidil (Rogaine, Rogaine Extra Strength for Men, Hair Regrowth Treatment) are sometimes used together in the treatment of male pattern hair loss. Typically, this kind of baldness is the result of genetic factors combined with the DHT hormone. 

Finasteride combats DHT’s effects on hair follicles that cause hair loss by reducing the production of the hormone. Minoxidil stimulates the follicles to get them working again. The drug further increases blood flow to the scalp, which helps the once-shrunken follicles to expand. This process reinvigorates hair growth at the same time. 

The combination of finasteride to reduce hair loss and minoxidil to promote hair growth may allow some cisgender men to treat their baldness successfully. 

Food Interactions

Sometimes the foods we eat and the beverages we drink can also interact with our medications.

Food and drink that may interact with finasteride include:

  • Alcohol (heavy drinking)

This list may not be complete, and there may be other foods and beverages that interact with this drug.

Finasteride and Dairy

There are no specific reactions noted with dairy products. 

Finasteride and Alcohol

There is clinical evidence that heavy drinking may negate the effect of the drug in some treatments, specifically when used to reduce the risk of prostate cancer.

For more information, please visit our page on finasteride and alcohol interactions.

Disease & Conditions Interactions

Sometimes certain medications can increase the risk of adverse side effects for patients with specific diseases or other medical conditions. 

According to the FDA, diseases, and medical conditions that are known to interact negatively with finasteride include:

  • Liver impairment
  • Aging – not right for people over the age of 65 
  • Not indicated for (recommended for the treatment of) children
  • Pregnancy or nursing 
  • It may make it challenging to detect high-grade prostate cancer

Please note that this list may not be complete, and there may be other diseases and medical conditions where patients should not take finasteride.

Finasteride and Prostate Cancer

Phase III clinical trials show that finasteride use may decrease the risk of low-grade prostate cancer in men aged 55 or older. A study consisting of 19,000 cisgender men aged 55 or older with no signs of prostate cancer found that regular use of finasteride could reduce the risk of developing it. 

The study isn’t conclusive, though, and there are some questions about whether taking the drug makes discovering high-grade prostate cancer more difficult. 

Finasteride and Depression

Depression and suicidal thoughts are a rare but possible side effect of taking the drug. Depression risk is potential with both Propecia and Proscar, which can even occur when there is no history of mental illness. 

Finasteride and Blood Pressure

Some people that take finasteride experience low blood pressure (hypotension). It’s an infrequent side effect of the drug, however.

Finasteride and Pregnancy

Those who are pregnant or breastfeeding should not take or handle finasteride tablets. 

For more information, please visit our page on finasteride and pregnancy risks.

Disclaimer: this article does not constitute or replace medical advice. If you have an emergency or a serious medical question, please contact a medical professional or call 911 immediately. To see our full medical disclaimer, visit our Terms of Use page.



Medically Reviewed by:

Paul Bossung

Dr. Paul Bossung, Pharm. D. is a Missouri Board of Pharmacy certified pharmacist. He practices at Mercy Hospital Jefferson in Festus, MO in the inpatient pharmacy.  Paul attended St. Louis College of Pharmacy (STLCOP) and graduated in 2018. He worked at SSM Health Cardinal Glennon for six years as a student pharmacist prior to graduating.OVERVIEWDOSAGESIDE EFFECTSINTERACTIONSHALF-LIFE

Generic Name: finasteride

Brands: Proscar, Propecia, Propecia Pro-Pak

Class: 5-alpha-reductase inhibitors

Availability: prescription required

Molecular Formula: C23H36N2O2

Substance UNII: 57GNO57U7G

What is Finasteride?

Finasteride is a 5-alpha-reductase inhibitor sold under the brand names Proscar and Propecia.

What is Finasteride Used For?

It is used for the treatment of enlarged benign prostate hyperplasia (enlarged prostate) when offered under the brand name Proscar. For benign prostate hyperplasia, the goal is to reduce symptoms associated with the condition, such as difficulty urinating. It takes six or more months to see improvement.

Propecia is for the treatment of male pattern hair loss.

How Does Finasteride Work?

It works by decreasing the production of the hormone dihydrotestosterone (DHT) in the body. DHT can trigger the enlargement of the prostate and even contribute to hair loss. Reduction of this hormone can therefore prevent prostate enlargement as well as decrease hair loss. 

How Long Does it Take for Finasteride to Work?

How long it takes to work depends on the form of the drug taken. For hair growth, it can take three to four months before the medication begins to affect. It will be six to nine months before there is significant hair regrowth.

For benign prostate hyperplasia, it takes six or more months to see improvement in relevant symptoms.

Do Not Use Finasteride If:

There are several situations where this medication may not be the right choice for you. According to the U.S National Library of Medicine, the following should not use finasteride:

  • Those who are pregnant or breastfeeding
  • Cisgender men who have had breast cancer
  • Anyone experiencing suicidal thoughts
  • Anyone with liver problems
  • Those with high-grade prostate cancer
  • People with a known allergy to 5-alpha reductase inhibitors

Please note that this list may not be complete, and there may be other situations where finasteride use is not advisable.

Disclaimer: this article does not constitute or replace medical advice. If you have an emergency or a serious medical question, please contact a medical professional or call 911 immediately. To see our full medical disclaimer, visit our Terms of Use page.


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