Important Safety Information for Minoxidil

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

In case of emergencies, please call 911 or go seek care at the nearest emergency room. Tell your care team right away about any side effects that bother you. If you experience adverse side effects, you can report them to the FDA. Visit www.fda.gov/medwatch or call 1-800-FDA-1088.

What is oral minoxidil used for?

Oral minoxidil is an FDA-approved medication for high blood pressure. At the low doses prescribed for hair loss, it is used off-label to treat hair loss (androgenetic alopecia) in men and women.

"Off-label" means a licensed clinician prescribes an FDA-approved medication for a use other than its original approval — a common and legal practice. Your care team will discuss whether low-dose oral use is right for you.

Boxed Warning — Minoxidil Tablets

Minoxidil tablets contain the powerful antihypertensive agent minoxidil, which may produce serious adverse effects. It can cause pericardial effusion, occasionally progressing to tamponade, and angina pectoris may be exacerbated. Minoxidil should be reserved for hypertensive patients who do not respond adequately to maximum therapeutic doses of a diuretic and two other antihypertensive agents.

In experimental animals, minoxidil caused several kinds of myocardial lesions as well as other adverse cardiac effects.

Minoxidil must be administered under close supervision, usually concomitantly with therapeutic doses of a beta-adrenergic blocking agent to prevent tachycardia and increased myocardial workload. It must also usually be given with a diuretic, frequently one acting in the ascending limb of the loop of Henle, to prevent serious fluid accumulation. Patients with malignant hypertension and those already receiving guanethidine should be hospitalized when minoxidil is first administered.

Note on hair-loss dosing: Low-dose oral minoxidil for hair loss is an off-label use, prescribed with provider oversight at significantly lower doses than those described in this Boxed Warning, which applies to minoxidil's FDA-approved use for severe hypertension.

Who should NOT use oral minoxidil?

  • Do not use if you are allergic to minoxidil.
  • Do not use if you have pheochromocytoma, a tumor in the adrenal gland.

What should I tell a licensed provider before starting oral minoxidil?

Tell a licensed provider about all medications you take, including prescription and over-the-counter medicines, vitamins, and herbal or dietary supplements.

Share your full medical history. In particular, tell a licensed provider if you have:

  • Any heart condition, blood pressure condition, kidney disease, or fluid retention history
  • You are pregnant, plan to become pregnant, or are breastfeeding

Pet safety

Minoxidil is toxic to cats and dogs. Do not allow pets to ingest this medication. Keep out of reach of children and pets.

Side effects — what to watch for

As with any medication, side effects are possible. Most people tolerate low-dose oral minoxidil well, but you should know what to watch for. Unlimited messaging with your care team — ask questions any time.

Commonly reported side effects include:

  • Unwanted hair growth on other parts of the body (such as the face or arms)
  • Fluid retention, including mild swelling of the hands, feet, or ankles
  • Swelling around the eyes
  • Headache
  • Lightheadedness or dizziness
  • Nausea
  • Insomnia

Minoxidil may cause changes to your EKG. Tell your doctor before an EKG if you are taking oral minoxidil.

Stop taking minoxidil and contact your care team right away if you experience:

  • Chest pain
  • Shortness of breath
  • Rapid heartbeat or palpitations
  • Significant swelling
  • Fainting
  • Sudden, unexplained weight gain

Self-monitoring tips from your care team:

  • Weigh yourself regularly. If you gain 5 or more pounds quickly, contact your care team.
  • Count your resting pulse. If your heart rate increases by 20 beats per minute or more over your normal resting rate, contact your care team right away.

Drug interactions and precautions

Minoxidil was originally a blood pressure medication. At hair loss doses the effect on blood pressure is usually minimal, but your care team will monitor this.

Tell your care team about any heart or blood pressure conditions, and about all medications you take, especially blood pressure drugs, diuretics, or other vasodilators.

  • Guanethidine: should be discontinued before starting minoxidil. Do not take oral minoxidil if you take guanethidine.
  • Alcohol may increase the blood pressure–lowering effect. Use caution when standing up quickly.

Do not start, stop, or change the dose of any medication without talking to your care team or your regular doctor.