What interactions occur between minoxidil and other medications?

From the Guidelines

Minoxidil can interact with several medications, requiring caution when used together, and its use should be carefully managed to avoid adverse effects, particularly in patients with cardiovascular conditions, as noted in the 2018 guideline for the prevention, detection, evaluation, and management of high blood pressure in adults 1. When considering the use of minoxidil, especially in combination with other medications, it's crucial to understand its mechanism of action as a vasodilator and how it can interact with other drugs.

• Blood pressure medications like guanethidine, beta-blockers, calcium channel blockers, and ACE inhibitors may enhance minoxidil's hypotensive effects, potentially causing excessive blood pressure lowering, as these combinations can create additive effects 1.
• Certain NSAIDs like ibuprofen may reduce minoxidil's effectiveness by inhibiting prostaglandin synthesis, which plays a role in minoxidil's mechanism of action.
• Corticosteroids and some immunosuppressants might increase fluid retention when used with minoxidil, worsening potential edema side effects. Patients taking minoxidil should inform their healthcare provider about all medications they're using, including over-the-counter drugs and supplements.

Key Considerations

• Those with cardiovascular conditions should be particularly cautious and have their blood pressure monitored regularly when using minoxidil alongside other medications.
• Dosage adjustments may be necessary when these drug combinations cannot be avoided, and the use of minoxidil with a diuretic and beta-blocker is generally recommended to mitigate its side effects, such as sodium and water retention and reflex tachycardia 1.
• The choice of medications and their combinations should be tailored to the individual patient, considering factors such as prior benefit, history of adverse events, contributing factors, including concomitant disease processes like CKD or diabetes, and patient financial limitations 1.

From the Research

Interactions between Minoxidil and Other Medications

• Minoxidil is a potent vasodilator that can cause serious side effects, including fluid retention, worsening of heart failure, reflex tachycardia, angina, myocardial infarction, pericardial effusion, and hypotension 2.
• When used to treat hypertension, minoxidil is often administered with a diuretic and an agent to control pulse rate, such as a beta blocker or a combined alpha-beta blocker, to mitigate its side effects 3.
• The use of minoxidil with other medications, such as midodrine, an alpha-adrenergic agonist, can help reduce ICU stay by shortening IV vasopressor usage in cases of severe circulatory shock 2.
• Tretinoin, a medication known to increase the percutaneous absorption of minoxidil, can be used in combination with minoxidil to enhance its response in treating androgenetic alopecia (AGA) 4.
• The combination of 5% minoxidil and 0.01% tretinoin once-daily therapy has been shown to be equivalent in efficacy and safety to conventional 5% minoxidil twice-daily therapy for the treatment of AGA 4.

Side Effects and Interactions

• Common side effects of topical minoxidil include irritant and allergic contact dermatitis on the scalp, as well as increased hair loss due to the synchronization of the hair cycle 5.
• Generalized hypertrichosis is a rare side effect of topical minoxidil, but can occur, especially in areas close to the site of application 6.
• Minoxidil can interact with other medications, such as diuretics and beta blockers, to increase the risk of side effects, such as hypotension and reflex tachycardia 3.