Important: This page is general information, not medical advice. It does not recommend or prescribe any treatment. Always consult your doctor or pharmacist before starting, stopping or changing any medicine.
Quick facts
- Drug class
- Arteriolar Vasodilator [EPC]
- How it is given
- oral
- Type
- human prescription drug
- RxNorm ID
- 197986
We do not publish dosing. How much of this medicine to take, how often, and for how long depends on your age, weight, kidney and liver function, other conditions and other medicines. That is a decision for the person who prescribes or dispenses it. Follow the directions on your own pack and ask your pharmacist if anything is unclear.
What it is used to treat
INDICATIONS AND USAGE Because of the potential for serious adverse effects, minoxidil tablets are indicated only in the treatment of hypertension that is symptomatic or associated with target organ damage and is not manageable with maximum therapeutic doses of a diuretic plus two other antihypertensive drugs. At the present time use in milder degrees of hypertension is not recommended because the benefit-risk relationship in such patients has not been defined. Minoxidil reduced supine diastolic blood pressure by 20 mm Hg or to 90 mm Hg or less in approximately 75% of patients, most of who had hypertension that could not be controlled by other drugs.
About this medicine
DESCRIPTION Minoxidil tablets contain minoxidil, an antihypertensive peripheral vasodilator. Minoxidil occurs as a white to off-white, crystalline powder, soluble in alcohol and propylene glycol; sparingly soluble in methanol; slightly soluble in water; practically insoluble in chloroform, acetone and ethyl acetate. The chemical name for minoxidil is 2,4-Pyrimidinediamine, 6-(1-piperidinyl)-, 3-oxide. The structural formula is represented below: Minoxidil tablets for oral administration contain either 2.5 mg or 10 mg of minoxidil. Inactive ingredients: anhydrous lactose, colloidal silicon dioxide, magnesium stearate, microcrystalline cellulose, and sodium starch glycolate. Chemical Structure
Who should not take it
CONTRAINDICATIONS Minoxidil tablets are contraindicated in pheochromocytoma, because it may stimulate secretion of catecholamines from the tumor through its antihypertensive action. Minoxidil tablets are contraindicated in those patients with a history of hypersensitivity to any of the components of the preparation.
Warnings
WARNINGS 1. Salt and Water Retention Congestive Heart Failure — concomitant use of an adequate diuretic is required — Minoxidil tablets must usually be administered concomitantly with a diuretic adequate to prevent fluid retention and possible congestive heart failure; a high ceiling (loop) diuretic is almost always required. Body weight should be monitored closely. If minoxidil is used without a diuretic, retention of several hundred milliequivalents of salt and corresponding volumes of water can occur within a few days, leading to increased plasma and interstitial fluid volume and local or generalized edema. Diuretic treatment alone, or in combination with restricted salt intake, will usually minimize fluid retention, although reversible edema did develop in approximately 10% of nondialysis patients so treated. Ascites has also been reported. Diuretic effectiveness was limited mostly by disease-related impaired renal function. The condition of patients with pre-existing congestive heart failure occasionally deteriorated in association with fluid retention although because of the fall in blood pressure (reduction of afterload), more than twice as many improved than worsened. Rarely, refractory fluid retention may require discontinuation of minoxidil. Provided that the patient is under close medical supervision, it may be possible to resolve refractory salt retention by discontinuing minoxidil for 1 or 2 days and then resuming treatment in conjunction with vigorous diuretic therapy. 2. Concomitant Treatment to Prevent Tachycardia is Usually Required Minoxidil increases the heart rate. Angina may worsen or appear for the first time during minoxidil treatment, probably because of the increased oxygen demands associated with increased heart rate and cardiac output. The increase in rate and the occurrence of angina generally can be prevented by the concomitant administration of a beta-adrenergic blocking drug or other sympathetic nervous system suppressant. The ability of beta-adrenergic blocking agents to minimize papillary muscle lesions in animals is further reason to utilize such an agent concomitantly. […]
Reported side effects
ADVERSE REACTIONS 1. Salt and Water Retention (see WARNINGS: Concomitant use of Adequate Diuretic is Required ) — Temporary edema developed in 7% of patients who were not edematous at the start of therapy. 2. Pericarditis, Pericardial Effusion and Tamponade (see WARNINGS ). 3. Dermatologic — Hypertrichosis — Elongation, thickening, and enhanced pigmentation of fine body hair are seen in about 80% of patients taking minoxidil tablets. This develops within 3 to 6 weeks after starting therapy. It is usually first noticed on the temples, between the eyebrows, between the hairline and the eyebrows, or in the side-burn area of the upper lateral cheek, later extending to the back, arms, legs, and scalp. Upon discontinuation of minoxidil, new hair growth stops, but 1 to 6 months may be required for restoration to pretreatment appearance. No endocrine abnormalities have been found to explain the abnormal hair growth; thus, it is hypertrichosis without virilism. Hair growth is especially disturbing to children and women and such patients should be thoroughly informed about this effect before therapy with minoxidil is begun. Allergic — Rashes have been reported, including rare reports of bullous eruptions, and Stevens-Johnson Syndrome. 4. Hematologic — Thrombocytopenia and leukopenia (WBC<3000/mm 3 ) have rarely been reported. 5. Gastrointestinal — Nausea and/or vomiting has been reported. In clinical trials the incidence of nausea and vomiting associated with the underlying disease has shown a decrease from pretrial levels. 6. Miscellaneous — Breast tenderness — This developed in less than 1 % of patients. 7. Altered Laboratory Findings — (a) ECG changes — Changes in direction and magnitude of the ECG T-waves occur in approximately 60% of patients treated with minoxidil. In rare instances a large negative amplitude of the T-wave may encroach upon the S-T segment, but the S-T segment is not independently altered. These changes usually disappear with continuance of treatment and revert to the pretreatment state if minoxidil is discontinued. […]
Interactions with other medicines
4. Drug interactions See " Interaction with Guanethidine " under WARNINGS .
If too much is taken
OVERDOSAGE There have been only a few instances of deliberate or accidental overdosage with minoxidil tablets. One patient recovered after taking 50 mg of minoxidil together with 500 mg of a barbiturate. When exaggerated hypotension is encountered, it is most likely to occur in association with residual sympathetic nervous system blockade from previous therapy (guanethidine-like effects or alpha-adrenergic blockage), which prevents the usual compensatory maintenance of blood pressure. Intravenous administration of normal saline will help to maintain blood pressure and facilitate urine formation in these patients. Sympathomimetic drugs such as norepinephrine or epinephrine should be avoided because of their excessive cardiac stimulating action. Phenylephrine, angiotensin II, vasopressin, and dopamine all reverse hypotension due to minoxidil, but should only be used if underperfusion of a vital organ is evident. Radioimmunoassay can be performed to determine the concentration of minoxidil in the blood. At the maximum adult dose of 100 mg/day, peak blood levels of 1641 ng/mL and 2441 ng/mL were observed in two patients, respectively. Due to patient-to-patient variation in blood levels, it is difficult to establish an overdosage warning level. In general, a substantial increase above 2000 ng/mL should be regarded as overdosage, unless the physician is aware that the patient has taken no more than the maximum dose. Oral LD 50 in rats has ranged from 1321–3492 mg/kg; in mice, 2456–2648 mg/kg.
Storing it safely
Store at 20° to 25°C (68° to 77° F). [See USP Controlled Room Temperature] DISPENSE IN TIGHT, LIGHT-RESISTANT CONTAINER.
Before you take anything new
Tell your pharmacist or doctor about every medicine you take — including ones bought without a prescription, herbal products and supplements. Interactions are one of the most common avoidable causes of harm from medicines, and a pharmacist can check your full list in a couple of minutes.
This page is built from the openFDA record of the U.S. Food and Drug Administration's approved labelling for this product, effective 21 January 2026. Label text has been shortened and reformatted for readability; safety wording has not been altered in meaning. FDA labelling describes products approved in the United States — brand names, strengths, formulations and approved uses may differ in your country. Always read the leaflet that comes with your own pack. PocketsInfo is not affiliated with, and is not endorsed by, the FDA. Retrieved 2026-07-30.