Important Safety Information for Oral Minoxidil

Warning: Serious Cardiac Effects
  • Minoxidil can cause pericardial effusion, the accumulation of too much fluid in the sac that surrounds the heart (pericardium). Pericardial effusion can progress to tamponade which increases pressure on the heart and keeps it from beating properly. This can result in sharp chest pain and difficulty breathing. Seek emergency treatment if this occurs.

  • When using minoxidil to treat high blood pressure, it should be reserved for patients who do not respond adequately to maximum therapeutic doses of a diuretic (water pill) and two other blood pressure lowering drugs.

  • When using minoxidil to treat high blood pressure, it must be administered under close supervision, usually with a beta-blocker to prevent increased heart rate (tachycardia) and increased the stress put on the heart muscle (myocardial workload). It must also usually be given with a diuretic to prevent serious fluid accumulation. 

  • When tested on animals, minoxidil caused lesions of the heart as well as other adverse heart effects.

  • Patients with malignant hypertension and those already receiving guanethidine should be hospitalized when minoxidil is first administered so that they can be monitored to avoid too rapid decreases in blood pressure.

What is the FDA-approved use of oral minoxidil?

Oral minoxidil is FDA-approved for symptomatic high blood pressure that is not controlled by a diuretic plus two other blood pressure lowering drugs. Your Ro-affiliated provider may recommend a lower dose of oral minoxidil (2.5 mg or 5 mg) as treatment of male pattern hair loss (androgenic alopecia).

Who should not use oral minoxidil?

Do not use oral minoxidil if:

  • You have pheochromocytoma, a tumor in the adrenal gland.

  • You have a known allergic reaction to oral minoxidil.


How should I take oral minoxidil?

Oral minoxidil can be taken with or without meals. You should take oral minoxidil exactly as prescribed and should not change your dosing regimen without discussing it with your provider first.

What should I tell my Ro-affiliated provider before using oral minoxidil?
  • Oral minoxidil has certain drug interactions. It’s important to tell your Ro-affiliated provider all of the medications you are currently taking, including prescription, over-the-counter medications, vitamins, and herbal and dietary supplements. 

Some medications to watch out for include:
  • Guanethidine should be discontinued before starting treatment

  • It’s important to share your entire medical history with your provider. In particular, tell your provider if you have a past history of:

    • Heart disease, including stroke, heart attack, or congestive heart failure

    • Kidney disease

Withholding or providing inaccurate information about your health and medical history in order to obtain treatment may result in harm, including, in some cases, death.


What are the most serious side effects that I or a caregiver should monitor for when taking oral minoxidil?

If you are experiencing a medical emergency, call 911 or seek immediate medical attention.

These serious side effects can occur with oral minoxidil. You or a caregiver should carefully monitor for these side effects, especially in the beginning of treatment and with dose changes.

  • Salt and water retention: Monitor for fluid retention and increase in body weight. If you quickly gain five or more pounds, or if there is any swelling or puffiness in the face, hands, ankles, or stomach area, this could be a sign that you are retaining body fluids. Contact your Ro-affiliated provider or your in-person provider. 

  • Increased heart rate (tachycardia): You should measure your heart rate by counting your pulse rate while you are resting. If you have an increase of 20 beats or more a minute over your normal pulse, contact your Ro-affiliated provider or your in-person provider immediately.

  • Pericarditis, Pericardial Effusion and Tamponade: Oral minoxidil can cause an accumulation of fluids in the sac surrounding the heart. Monitor for sharp pain in the chest, arm, or shoulder; signs of severe indigestion; or shortness of breath, dizziness, lightheadedness, and fainting. These could be signs of serious heart problems and you should seek immediate emergency care.

  • Hazard of Rapid Control of Blood Pressure: A sudden or too large of a drop in blood pressure can lead to fainting, heart attack, and loss of blood flow to certain organs.

What are the most common side effects of oral minoxidil?
  • Salt and water retention

  • Elongation, thickening, and enhanced pigmentation of fine body hair

You are encouraged to report negative side effects of prescription products to the FDA. Visit or call 1-800-FDA-1088.

This information is not comprehensive. Please see the full Prescribing Information for complete safety information.