From the Guidelines
Minoxidil can cause several side effects, including hirsutism, pericardial effusion, and requires a loop diuretic, as noted in the 2018 acc/aha/aapa/abc/acpm/ags/apha/ash/aspc/nma/pcna guideline for the prevention, detection, evaluation, and management of high blood pressure in adults 1.
Common Side Effects
- Scalp irritation, itching, dryness, flaking, and redness at the application site
- Increased facial or body hair growth, especially when the medication drips onto other areas
- Initial hair shedding in the first few weeks of use, which is actually a sign the medication is working as new hair cycles begin
Less Common Side Effects
- Headaches, acne, and facial swelling
- Burning sensations, especially on damaged skin, due to the topical solution containing alcohol
Concerning Side Effects
- Rapid heartbeat, chest pain, dizziness, sudden weight gain, swelling in the hands or feet, and lightheadedness, which may indicate cardiovascular effects from systemic absorption
Important Considerations
- Minoxidil should only be considered if all other pharmacological agents prove ineffective in resistant hypertension, due to its potential side effects and the need for careful monitoring 1.
- The use of minoxidil in combination with other medications, such as diuretics and beta blockers, may be necessary to minimize side effects and maximize efficacy 1.
From the FDA Drug Label
The most common side effects are itching and skin irritation of the treated area of the scalp. Stop use and ask a doctor if
- chest pain, rapid heartbeat, faintness, or dizziness occurs
- sudden, unexplained weight gain occurs
- your hands or feet swell
- scalp irritation or redness occurs
- unwanted facial hair growth occurs
- you do not see hair regrowth in 4 months Unwanted hair growth on the face and other parts of the body has been reported in women. But it is rare and reversible If you develop unwanted hair, stop using minoxidil topical solution 5%.
Common side effects of minoxidil include:
- Itching
- Skin irritation of the treated area of the scalp Less common but serious side effects include:
- Chest pain
- Rapid heartbeat
- Faintness or dizziness
- Sudden, unexplained weight gain
- Swelling of hands or feet
- Unwanted facial hair growth Rare side effects include unwanted hair growth on the face and other parts of the body, which is reversible if minoxidil use is stopped 2
From the Research
Minoxidil Side Effects
- The most common adverse reactions of the topical formulation are limited to irritant and allergic contact dermatitis on the scalp 3.
- Increased hair loss can occur during minoxidil use, due to the synchronization of the hair cycle that the treatment induces 3.
- Systemic adverse effects of low-dose oral minoxidil include lightheadedness, fluid retention, tachycardia, headache, periorbital edema, and insomnia 4.
- Hypertrichosis is a common side effect of low-dose oral minoxidil, occurring in 15.1% of patients 4.
- Cardiovascular complications, such as ischemic heart disease, left ventricular hypertrophy, pleural effusions, and pericardial effusions, have been associated with oral minoxidil use 5.
- Systemic adverse effects of low-dose oral minoxidil in patients with hypertension or arrhythmia include lightheadedness, fluid retention, general malaise, tachycardia, and headache 6.
- Topical minoxidil is generally well-tolerated, with approximately 1.4% of the drug being absorbed through the skin 7.
Specific Side Effects
- Allergic reactions to the nonactive ingredient propylene glycol can occur, especially in galenic topical solutions 3.
- Follicles in the telogen phase may shed soon after starting minoxidil treatment, usually to be replaced by new, thicker hairs in a new anagen phase 3.
- Prior treatment with doxazosin or with three or more antihypertensive drugs may be associated with a higher risk of discontinuation of low-dose oral minoxidil 6.