Minoxidil Side Effects

Not all side effects for minoxidil may be reported. You should always consult a doctor or healthcare professional for medical advice. Side effects can be reported to the FDA here.

For the Consumer

Applies to minoxidil: oral tablet

In addition to its needed effects, some unwanted effects may be caused by minoxidil. In the event that any of these side effects do occur, they may require medical attention.

You should check with your doctor immediately if any of these side effects occur when taking minoxidil:

More common
  • Fast or irregular heartbeat
  • weight gain (rapid) of more than 5 pounds (2 pounds in children)
Less common
  • Chest pain
  • shortness of breath

If any of the following side effects occur while taking minoxidil, check with your doctor or nurse as soon as possible:

More common
  • Bloating
  • flushing or redness of skin
  • swelling of feet or lower legs
Less common
  • Numbness or tingling of hands, feet, or face
Rare
  • Skin rash and itching

Some of the side effects that can occur with minoxidil may not need medical attention. As your body adjusts to the medicine during treatment these side effects may go away. Your health care professional may also be able to tell you about ways to reduce or prevent some of these side effects. If any of the following side effects continue, are bothersome or if you have any questions about them, check with your health care professional:

More common
  • Increase in hair growth, usually on face, arms, and back
Less common or rare
  • Breast tenderness in males and females
  • headache

This medicine causes a temporary increase in hair growth in most people. Hair may grow longer and darker in both men and women. This may first be noticed on the face several weeks after you start taking minoxidil. Later, new hair growth may be noticed on the back, arms, legs, and scalp. Talk to your doctor about shaving or using a hair remover during this time. After treatment with minoxidil has ended, the hair will stop growing, although it may take several months for the new hair growth to go away.

For Healthcare Professionals

Applies to minoxidil: compounding powder, oral tablet

General

Minoxidil is usually administered with a beta-blocker to counteract the increased cardiac output and cardiac work associated with profound minoxidil-induced vasodilation and with a loop diuretic to counteract the sodium and water retaining properties of minoxidil.[Ref]

Cardiovascular

Cardiovascular side effects are related to peripheral vasodilation and sodium and water retention, and include hypotension, sinus tachycardia, provocation of angina, edema, and weight gain. Edema is expected without concomitant use of a diuretic agent.

Pericardial effusions occur in up to 5% of patients and may be more likely in patients with renal insufficiency. Reversible, nonspecific ST-T wave electrocardiographic changes occur in 30% to 90% of patients.[Ref]

The hypotensive effect of minoxidil may last for days after drug discontinuation.

The mechanism of minoxidil-associated angina is not known. Theories include a coronary "steal" phenomenon secondary to coronary vasodilation, resulting in relative ischemia to hypoperfused areas of myocardium and increased cardiac work secondary to minoxidil-induced reflex tachycardia.

Nonspecific ST-T wave changes are not necessarily associated with cardiac disease.

The incidence of pericardial effusion in minoxidil-treated uremic patients is greater than that expected in non-treated uremic patients. Tamponade is reported in up to 23% of minoxidil-associated pericardial effusions, which has been fatal in rare cases.

Rare cases of pulmonary hypertension have been associated with minoxidil. Pulmonary hypertension is thought to be due to a minoxidil-induced increase in cardiac output and in pulmonary blood flow.

Hemorrhagic and degenerative lesions of the right atrium and focal necrosis of the left ventricular papillary muscle have been described in dog studies, but not in monkeys. No data are available in humans.[Ref]

Dermatologic

Hypertrichosis usually presents as elongated and hyperpigmented new hair. Hypertrichosis is reversible. Hypertrichosis usually begins at the temples, forehead, and between the eyebrows, but may involve the trunk, extremities, and scalp. Some studies have shown hypertrichosis to occur at lower doses in females, although it may be that females were more distressed by this side effect, and presented these findings earlier than men did.[Ref]

Dermatologic side effects are common. Hypertrichosis occurs in 30% to 80% of patients within the first 3 to 6 weeks of therapy. A fatal case of toxic epidermal necrolysis has also been reported.[Ref]

Hypersensitivity

Hypersensitivity reactions such as contact dermatitis, desquamative and bullous rashes, and Stevens-Johnson syndrome have been reported in less than 1% of patients.[Ref]

Gastrointestinal

Gastrointestinal side effects are uncommon and include nausea and vomiting.[Ref]

Hematologic

A case of thrombocytopenia associated with minoxidil, which recurred upon rechallenge, has been reported.[Ref]

Hematologic side effects, such as decreased hematocrit and hemoglobin, are usually related to dilution from minoxidil-induced sodium and water retention.[Ref]

Nervous system

Nervous system side effects are usually limited to headache in approximately 6% and dizziness in approximately 2% of patients. Rare cases of general fatigue have been reported.[Ref]

A case of bilateral optic neuritis, followed by atrophy and vision loss, was associated with minoxidil, despite the fact that the patient was taking other medications as well.[Ref]

Immunologic

Immunologic side effects are extremely rare.[Ref]

A case of a lupus syndrome associated with the development of a speckled ANA pattern has been associated with minoxidil. The patient had previously taken hydralazine, but did not test positive for ANA until after minoxidil was substituted for hydralazine.[Ref]

Endocrine

Endocrine side effects include at least one case of pseudoacromegaly. A case of pseudoacromegaly which resulted from long-term (10 years) use of minoxidil (50 mg/day) has been reported.[Ref]

References

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5. Allon M, Hall D, Macon EJ "Prolonged hypotension after initial minoxidil dose." Arch Intern Med 146 (1986): 2075-6

6. Reichgott MJ "Minoxidil and pericardial effusion: an idiosyncratic reaction." Clin Pharmacol Ther 30 (1981): 64-70

7. Zarate A, Gelfand MC, Horton JD, et al "Pericardial effusion associated with minoxidil therapy in dialyzed patients." Int J Artif Organs 3 (1980): 15-7

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11. Krehlik JM, Hindson DA, Crowley JJ, Knight LL "Minoxidil-associated pericarditis and fatal cardiac tamponade." West J Med 143 (1985): 527-9

12. Jackson RV, Williamson MM, Seneviratne B, Gordon RD "Long term minoxidil therapy and renal function, cardiac function, hypertrichosis and blood pressure." Aust N Z J Med 13 (1983): 39-44

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23. Miller DD, Love DW "Drug therapy reviews: evaluation of minoxidil." Am J Hosp Pharm 37 (1980): 808-14

24. Hagstam K-E, Lundgren R, Wieslander J "Clinical experience of long-term treatment with minoxidil in severe arterial hypertension." Scand J Urol Nephrol 16 (1982): 57-63

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26. Leenen FH, Smith DL, Unger WP "Topical minoxidil: cardiac effects in bald men." Br J Clin Pharmacol 26 (1988): 481-5

27. Tosti A, Bardazzi F, De Padove MP, Caponeri GM, Melino M, Veronesi S "Contact dermatitis to minoxidil." Contact Dermatitis 13 (1985): 275-6

28. Ruas E, Goncalo M, Figueiredo A, Goncalo S "Allergic contact dermatitis from minoxidil." Contact Dermatitis 26 (1992): 57-8

29. Degreef H, Hendrickx I, Dooms-Goossens A "Allergic contact dermatitis to minoxidil." Contact Dermatitis 13 (1985): 194-5

30. Price VH "Topical minoxidil in extensive alopecia areata, including 3-year follow-up." Dermatologica 175 (1987): 36-41

31. Pettinger WA, Mitchell HC "Minoxidil: an alternative to nephrectomy for refractory hypertension." N Engl J Med 289 (1973): 167-73

32. Fisher AA "Unusual acute, nonallergic eruptions of the scalp from combined use of minoxidil and retinoic acid." Cutis 51 (1993): 17-8

33. Veraldi S, Benelli C, Pigatto PD "Occupational allergic contact dermatitis from minoxidil." Contact Dermatitis 26 (1992): 211-2

34. Ackerman BH, Townsend ME, Golden W, Bryan AB "Pruritic rash with actinic keratosis and impending exfoliation in a patient with hypertension managed with minoxidil." Drug Intell Clin Pharm 22 (1988): 702-3

35. Gonzalez M, Landa N, Gardeazabal J, Calderon MJ, Bilbao I, Perez JLD "Generalized hypertrichosis after treatment with topical minoxidil." Clin Exp Dermatol 19 (1994): 157-8

36. Karaoui LR, Chahine-Chakhtoura C "Fatal toxic epidermal necrolysis associated with minoxidil." Pharmacotherapy 29 (2009): 460-7

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40. Toriumi DM, Konior RJ, Berktold RE "Severe hypertrichosis of the external ear canal during minoxidil therapy." Arch Otolaryngol Head Neck Surg 114 (1988): 918-9

41. Limas CJ, Freis ED "Minoxidil in severe hypertension with renal failure: effect of its addition to conventional antihypertensive drugs." Am J Cardiol 31 (1973): 355-61

42. Wilson C, Walkden V, Powell S, et al "Contact dermatitis in reaction to 2% topical minoxidil solution." J Am Acad Dermatol 24 (1991): 661-2

43. Peitzman SJ, Martin C "Thrombocytopenia and minoxidil." Ann Intern Med 92 (1980): 874

44. Gombos GM "Bilateral optic neuritis following minoxidil administration." Ann Ophthalmol 15 (1983): 259-61

45. Nguyen KH, Marks JG Jr "Pseudoacromegaly induced by the long-term use of minoxidil." J Am Acad Dermatol 48 (2003): 962-5

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