How does this medication work? What will it do for me?

Minoxidil belongs to a group of medications known as vasodilators. It is used to control severely elevated blood pressure that is not manageable with a water pill and two other blood pressure medications. After the first dose of minoxidil, blood pressure usually starts to go down within one-half hour.

High blood pressure increases the work of the heart, and it may damage the heart, kidneys, brain, and blood vessels if left for too long. Minoxidil works by relaxing the blood vessels so the blood passes through them more easily. This helps to lower blood pressure.

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.

What form(s) does this medication come in?

2.5 mg
Each round, white, scored tablet, embossed with a "U" and "121" on one side and "2½" on the other, contains minoxidil 2.5 mg. Nonmedicinal ingredients: cornstarch, lactose, magnesium stearate, microcrystalline cellulose, and silicon dioxide. This medication does not contain gluten.

10 mg
Each round, white, scored tablet, embossed with a "U" and "137" on one side and "10" on the other, contains minoxidil 10 mg. Nonmedicinal ingredients: cornstarch, lactose, magnesium stearate, microcrystalline cellulose, and silicon dioxide. This medication does not contain gluten.

How should I use this medication?

How should I use this medication?

The recommended starting dose of minoxidil for adults is 5 mg given in 2 divided doses (i.e., 2.5 mg taken 2 times a day).

If the desired blood pressure is not achieved, your doctor may increase the dose to 10 mg daily after 3 days, 20 mg daily after an additional 3 days, and 40 mg daily after 3 more days. These are only guidelines. Some people may require higher doses to keep their blood pressure under control.

The dose for children less than 12 years of age is based on weight. The recommended dose is 0.2 mg per kilogram of body weight each day, divided into 2 equal doses and will be calculated by your doctor.

Many things can affect the dose of 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.

Minoxidil is usually taken along with two other medications to help lower blood pressure and prevent side effects of minoxidil. It may be taken with food or on an empty stomach. Swallow this medication whole with water or other liquids.

It is important to take this medication exactly as prescribed by your doctor. If you miss a dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. Call the doctor if you miss two or more doses in a row. 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.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Who should NOT take this medication?

Do not take minoxidil if you:

  • are allergic to minoxidil or any ingredients of the medication
  • have a condition caused by a kind of tumour called pheochromocytoma
  • have pulmonary hypertension related to mitral stenosis (narrowing of the mitral valve passageway)

What side effects are possible with this medication?

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.

  • increase in hair growth, usually on the face, arms, and back

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:

  • bloating
  • difficulty breathing, especially when lying down
  • dizziness or lightheadedness
  • fast or irregular heartbeat
  • rapid weight gain of more than 2 kg (1 kg in children)
  • shortness of breath
  • signs of bleeding (e.g., bloody nose, blood in urine, coughing blood, bleeding gums, cuts that don't stop bleeding)
  • skin rash and itching
  • swelling of the feet or lower legs

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

  • signs of a severe skin reaction (e.g., blistering, peeling, a rash covering a large area of the body, a rash that spreads quickly, or a rash combined with fever or discomfort)
  • signs of heart attack (e.g., chest pain, arm or shoulder pain, signs of severe indigestion, nausea and vomiting, or sweating)

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.

Are there any other precautions or warnings for this medication?

Before you begin taking 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 take this medication.

Drowsiness/reduced alertness: Minoxidil may affect the mental or physical abilities needed to drive or operate machinery. Avoid driving, operating machinery, or performing other hazardous tasks until you have determined how this medication affects you.

Heart disease: People with certain types of heart disease may be at an increased risk of adverse reactions to minoxidil. If you have a history of heart attack or stroke, heart disease, blood vessel disease, or angina (chest pain), 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.

Kidney function: If you have kidney disease or reduced kidney 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.

Weight: Minoxidil can cause fluid to build up in the body, possibly leading to congestive heart disease. This can be controlled with diuretic medication (water pills) if necessary. Weigh yourself every day while taking minoxidil. If your weight increases by 2 kg (1 kg for children), call your doctor right away. Contact your doctor as soon as possible if you experience swollen feet, ankles, or wrists, or difficulty breathing.

Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: This medication passes into breast milk. If you are a breast-feeding mother and are taking minoxidil, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

What other drugs could interact with this medication?

There may be an interaction between minoxidil and any of the following:

  • acetazolamide
  • alfuzosin
  • aliskiren
  • amifostine
  • amphetamines (e.g., dextroamphetamine, lisdexamphetamine)
  • angiotensin converting enzyme inhibitors (ACEIs; e.g., captopril, ramipril)
  • angiotensin II receptor blockers (ARBs; e.g., irbesartan, losartan)
  • beta-blockers (e.g., atenolol, metoprolol, propranolol)
  • calcium channel blockers (e.g., amlodipine, nifedipine, verapamil)
  • cyclosporine
  • diazoxide
  • dipyridamole
  • diuretics (water pills; e.g., furosemide, hydrochlorothiazide)
  • doxazosin
  • epoprostenol
  • ginger
  • ginseng
  • guanethidine
  • methylphenidate
  • monoamine oxidase inhibitors (MAOIs; e.g., moclobemide, phenelzine, selegiline, tranylcypromine)
  • nitrates (e.g., isosorbide dinitrate, nitroglycerin)
  • pentoxifylline
  • phosphodiesterase-5 inhibitors (e.g., sildenafil, tadalafil)
  • quinine
  • rituximab
  • terazosin
  • yohimbine

If you are taking any of these medications, speak with your doctor or pharmacist. 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. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications 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.