Oral Minoxidil Interactions: 7 Medications and Supplements to Know About

Oral minoxidil was originally FDA approved to treat high blood pressure. But it’s now commonly prescribed off-label in low doses for hair loss. Even at these lower doses, oral minoxidil can affect your heart and blood vessels. So certain medication, supplement, and substance interactions remain a concern.

Most minoxidil interactions are related to the medication’s effects on blood pressure, heart rate, and fluid balance. Here’s what to know before starting treatment.

Oral minoxidil interactions at a glance

Most interactions with oral minoxidil involve medications or substances that also affect your cardiovascular system. Depending on the combination, these interactions may increase the risk of low blood pressure, a fast heartbeat, or swelling.

While it’s not a comprehensive list, below are examples of medications and substances that can interact with oral minoxidil:

• Blood pressure medications, such as lisinopril (Zestril, Qbrelis) and amlodipine (Norvasc, Katerzia, Norliqva)

• Erectile dysfunction (ED) medications, such as sildenafil (Viagra) and tadalafil (Cialis)

• Guanethidine, which is no longer available in the U.S.

• Medications that increase heart rate, such as pseudoephedrine (Sudafed)

• Corticosteroids, such as prednisone

• Alcohol

• Certain herbal supplements, such as yohimbe or stimulant-containing supplements

If you’re taking one of the above medications or supplements, it doesn’t necessarily mean you can’t take oral minoxidil. But your healthcare team should review your current medication list to determine if adjustments are needed.

Below, we cover how to manage seven potential minoxidil interactions.

1. Blood pressure medications

Oral minoxidil widens blood vessels, which is why it’s prescribed at higher doses to lower blood pressure. But it can still have this effect at the low doses used for hair loss. Taking it with other blood pressure medications may cause your blood pressure to drop too low. This can increase the risk of dizziness, fainting, and falls.

Examples of blood pressure medications include:

• Angiotensin-converting enzyme (ACE) inhibitors, such as lisinopril

• Angiotensin II receptor blockers (ARBs), such as losartan (Cozaar)

• Calcium channel blockers, such as amlodipine

• Beta blockers, such as metoprolol (Lopressor, Toprol XL)

Swelling is another possible minoxidil side effect. Taking it with blood pressure medications like amlodipine, which can also cause swelling, may worsen this effect.

Tell your prescriber if you take medication for high blood pressure before starting minoxidil. They may recommend checking your blood pressure at home and watching for symptoms of low blood pressure or increased swelling. Get medical attention right away if you faint or experience symptoms such as severe dizziness, chest pain, or trouble breathing.

2. Erectile dysfunction medications

ED medications, such as sildenafil and tadalafil, also relax blood vessels and can lower blood pressure. Like blood pressure medications, taking them with oral minoxidil may increase the risk of low blood pressure.

Some ED medications are taken only as needed. Others, including tadalafil, can be taken every day. How often you take an ED medication affects how long its blood-pressure-lowering effects may combine with minoxidil’s:

• Daily tadalafil: Taking daily tadalafil and minoxidil together causes an ongoing increased risk of low blood pressure.

• As-needed tadalafil: When taken as needed, tadalafil can exaggerate minoxidil's blood pressure effects for up to 36 hours after a dose.

• Other ED medications: With shorter-acting ED medications, there's a briefer window for an interaction. But the risk of low blood pressure can still be significant around each dose.

Ask your healthcare professional before taking an ED medication with oral minoxidil, even if you’re only planning to take it as needed. They can help determine if it’s safe to combine them.

3. Guanethidine

Guanethidine is an older medication used to treat high blood pressure. It’s no longer available in the U.S., but it has a well-known interaction with oral minoxidil.

Taking guanethidine with minoxidil can cause significant orthostatic hypotension — a sudden drop in blood pressure when standing up. This can lead to severe dizziness or fainting.

4. Medications that increase heart rate

One potential side effect of oral minoxidil is a fast heart rate. Combining it with other medications that increase heart rate may make this side effect more noticeable.

Examples of medications that can increase heart rate include:

• Stimulants, such as Adderall (amphetamine salts) and phentermine (Adipex-P, Lomaira)

• Some decongestants, such as pseudoephedrine

• Certain asthma medications, such as albuterol (Ventolin HFA)

This doesn’t necessarily mean you can’t take one of these medications with minoxidil. But it’s best to check with a healthcare professional first. If the combination is OK for you, they may want to monitor your heart rate, especially if you’re just starting oral minoxidil. Let your healthcare professional know if you develop a racing, pounding, or fluttering heart rate.

5. Corticosteroids

Corticosteroids, such as prednisone, can cause your body to retain sodium and water. Oral minoxidil can also cause fluid retention. Taking minoxidil with a corticosteroid may increase the risk of swelling in your feet, ankles, or legs.

Tell your healthcare professional if you take a corticosteroid before starting oral minoxidil. Contact them if you notice new or worsening swelling or rapid weight gain.

6. Alcohol

Alcohol can temporarily lower blood pressure. Drinking alcohol while taking oral minoxidil may increase the risk of dizziness, lightheadedness, and fainting. It may also worsen hangover symptoms in some people.

You don’t necessarily need to avoid alcohol completely with minoxidil. But it’s a good idea to talk to your healthcare team about how much, if any, is OK for you to consume. If you choose to drink alcohol, pay attention to how you feel, especially if you’re just starting minoxidil or have recently increased your dose.

7. Certain herbal and dietary supplements

Some herbal and dietary supplements can also affect blood pressure or heart rate. Examples include yohimbe, high-dose caffeine, and other stimulant-containing supplements. It’s also important to know that some supplements may contain undisclosed ingredients that could interact with minoxidil. So the brand you buy matters.

Tell your prescriber or pharmacist about any supplements you take before starting oral minoxidil. They can help identify potential interactions and how to manage them.

Good to know: Caffeine is found in a variety of beverages, including energy drinks, coffee, and tea. Check with your healthcare team about how much caffeine, if any, is OK for you with minoxidil.

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Written by:

Alyssa Billingsley, PharmD

Alyssa Billingsley, PharmD, is the director of pharmacy content for GoodRx. She has over a decade of experience as a pharmacist and has worked in clinical, academic, and administrative roles.

Reviewed by:

Christina Aungst, PharmD, MWC

Christina Aungst, PharmD, MWC is a senior pharmacy editor for GoodRx. She began writing for GoodRx Health in 2019.

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