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Overview: Minoxidil is used to treat severe high blood pressure, generally when other medicines have not worked. It works by helping relax blood vessels in your body. Common side effects include nausea and vomiting, fluid retention, and unusual hair growth. Serious side effects include heart failure, chest pain, and (rarely) a serious condition involving swelling around the heart, called pericarditis.

Uses

What is minoxidil used for?

Minoxidil is commonly used to treat severe high blood pressure (hypertension), generally when other medicines have not worked. 

Minoxidil may also be used for other conditions as determined by your healthcare provider.

How does minoxidil work (mechanism of action)?

Minoxidil helps to relax blood vessels in your body. This allows blood to flow more easily through the vessels, which lowers blood pressure. Lowering blood pressure is important to prevent problems with your heart or kidneys and to decrease the risk of stroke or heart attack. 

How is minoxidil supplied (dosage forms)?

Brands and other names

  • Loniten
  • Minodyl

Dosage forms and strengths

  • 2.5 mg oral tablets
  • 10 mg oral tablets

Minoxidil is also available in a topical version that is applied to the scalp. See Minoxidil topical for more information. 

How should I store minoxidil?

Minoxidil should be stored at room temperature, between 68 F to 77 F (20 C to 25 C). It can be exposed to temperatures between 59 F to 86 F (15 C to 30 C) for shorter periods of time, such as when transporting it. Store in a cool, dry place.

Side Effects

What are the most common side effects of minoxidil?

The most common side effects of minoxidil are listed below. Tell your healthcare provider if you have any of these side effects that bother you.

  • Nausea and vomiting
  • Fluid retention 
  • Fast heartbeat 
  • Increased growth and darkening of body hair

There may be other side effects of minoxidil that are not listed here. Contact your healthcare provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088. In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of minoxidil?

While less common, the most serious side effects of minoxidil are described below, along with what to do if they happen.

Heart Failure. Minoxidil may cause fluid retention and increase your risk of heart failure. Tell your healthcare provider right away if you have any of the following symptoms of heart failure.

  • Shortness of breath or trouble breathing, especially while lying down
  • Swelling in your feet, ankles, or legs
  • Unusually fast weight gain
  • Unusual tiredness

Chest Pain. Minoxidil may cause a fast heartbeat, which can lead to chest pain. Chest pain can be a symptom of a heart attack. The risk of chest pain is higher in people who have heart disease. Do not take minoxidil if you have had a recent heart attack without talking to your healthcare provider. Get emergency help if you have any of the following symptoms.

  • Chest pain or pressure
  • Fast or abnormal heartbeat
  • Trouble breathing
  • Pain in your back, jaw, throat, or arm
  • Sweating, upset stomach, vomiting, or dizziness

Pericarditis. Minoxidil may cause pericarditis, which is a rare but serious condition involving swelling around the heart. Get emergency help if you have any of the following symptoms.

  • Chest pain or discomfort
  • Shortness of breath or trouble breathing
  • Painful cough
  • Feeling unusually tired or weak

Low Blood Pressure (Hypotension). Minoxidil may cause low blood pressure. If you feel faint or dizzy, lie down. Tell your healthcare provider right away if you have any of the following symptoms of low blood pressure.

  • Dizziness, feeling lightheaded, or fainting
  • Confusion
  • Feeling weak or tired

Severe Allergic Reactions. Minoxidil may cause allergic reactions, which can be serious. Stop taking minoxidil and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching, skin rash, or pale red bumps on the skin called hives
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Warnings & Precautions

Who should not use minoxidil?

Allergies to Ingredients. People who are allergic to any of the following should not take minoxidil.

  • Loniten
  • Minodyl
  • Minoxidil
  • Any of the ingredients in the specific product dispensed

Your pharmacist can tell you all of the ingredients in the specific minoxidil products they stock.

Pheochromocytoma. People with pheochromocytoma, a condition affecting the adrenal glands, should not take minoxidil.

What should I know about minoxidil before using it?

Do not take minoxidil unless it has been prescribed to you by a healthcare provider. Minoxidil is typically taken in combination with other medicines to help reduce the risk for serious side effects. Take it as prescribed. 

Do not stop taking this medicine without talking to your healthcare provider. Stopping this or any of your medicines for high blood pressure may increase your risk for a heart attack and stroke.

Do not share minoxidil with other people, even if they have the same condition as you. It may harm them.

Keep minoxidil out of the reach of children.

Minoxidil can affect your alertness or coordination. Do not drive or do other activities that require alertness or coordination until you know how minoxidil affects you.

This medicine can cause increased growth and darkening of your body hair. This effect is not permanent.

Keep all appointments with your healthcare provider for bloodwork and to check your weight while you are taking this medicine. This is to monitor for any signs of fluid retention or changes to the levels of certain minerals in your body, called electrolytes. 

What should I tell my healthcare provider before using minoxidil?

Tell your healthcare provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them determine if minoxidil is right for you.

In particular, make sure that you discuss any of the following.

Current and Past Health Conditions. Tell your healthcare provider if you have any of the following.

  • Heart problems, including heart failure or a recent heart attack
  • Problems with your circulation
  • Kidney problems

Other Medicines and Supplements. Minoxidil may interact with other medicines and supplements. Before taking minoxidil, tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.

Pregnancy. It is not known if or how minoxidil could affect pregnancy or harm an unborn baby. Tell your healthcare provider if you are or plan to become pregnant. Your healthcare provider will advise you if you should take minoxidil while you are pregnant or trying to get pregnant.

Breastfeeding. Do not take minoxidil while you are breastfeeding. Minoxidil can pass into breast milk. Tell your healthcare provider if you are breastfeeding or plan to breastfeed.

Interactions

Does minoxidil interact with foods or drinks?

There are no known interactions between minoxidil and foods or drinks.

It is unknown if drinking alcohol will affect minoxidil. The risk of dizziness may be increased if you drink alcohol while taking minoxidil. 

Does minoxidil interact with other medicines (drug interactions)?

Always tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

In particular, make sure that you discuss if you are using any other medicine for high blood pressure or a medicine for heart problems before taking minoxidil.

This may not be a complete list of medicines that can interact with minoxidil. Always check with your healthcare provider.

Does interact with other drugs you are taking?

Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally use too much minoxidil?

If you or someone else has used too much minoxidil, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of minoxidil?

It is important not to miss or skip doses of this medicine. If you miss a dose, skip the missed dose and take the next dose at the usual scheduled time. Do not take double or extra doses.