Minoxidil Side Effects: What Are They and Are They Common?

Kristin Hall, FNP

Medically reviewed by Kristin Hall, FNP

Written by Our Editorial Team

Last updated 9/29/2022

Male pattern baldness, or androgenetic alopecia, is a common form of hair loss that often starts to affect men in their 20s, 30s and 40s. 

If you’re starting to notice the early signs of male pattern baldness, you may benefit from using medication to protect your hair from damage, decrease hair shedding and promote normal hair growth. 

Minoxidil is a topical medication that’s used to treat hair loss. Along with finasteride, it’s one of the most widely used and effective treatment options for increasing hair growth and preventing male pattern baldness from becoming more severe. 

Like all medications, minoxidil has both primary effects and side effects. The good news is that minoxidil generally only causes mild side effects, most of which can be treated by making small changes to the way you use this medication. 

However, it’s important that you’re aware of all of minoxidil’s potential effects before you begin treatment.

Below, we’ve listed all of the known side effects of minoxidil, as well as detailed information on how common side effects are from minoxidil use.

We’ve also explained what you can do if you develop side effects while using minoxidil to treat and prevent hair loss.

The Basics of Minoxidil

Before we get into potential side effects of minoxidil, it’s important to quickly go over the basics of what minoxidil is and how it works as a treatment for hair loss.

Minoxidil is a topical medication that’s used to stimulate hair growth. It’s available as a solution and as a topical foam. Unlike finasteride, minoxidil is available over the counter, meaning it can be purchased without a prescription.

Although the precise mechanism of action for minoxidil isn’t fully understood, researchers think that it promotes hair growth by doing two main things: moving hair follicles into an active growth state and stimulating blood flow throughout your scalp.

Your hair grows as part of a multi-phase cycle referred to as the hair growth cycle. Experts think that minoxidil works by moving your hairs into the anagen phase of their cycle (a phase in which your hair actively grows to its full length), which helps to promote more consistent hair growth.

As for stimulating blood flow, research suggests that minoxidil helps to dilate the blood vessels in your scalp, allowing a larger volume of blood to flow to your hair follicles and supply vitamins, minerals and other essential nutrients.

Research shows that minoxidil works well, with many men who use it reporting a real difference in hair density and an increase in hair growth as a result of minoxidil treatment.

For example, in one study published in the Journal of the American Academy of Dermatology in 2004, more than 84 percent of men who used minoxidil rated it as either very effective, effective or moderately effective at stimulating hair regrowth. 

Minoxidil is simple to use, with most men applying it twice a day to their entire scalp for optimal results. 

What Are the Side Effects of Minoxidil?

Because minoxidil is a widely used, thoroughly tested medication, its side effects are well known amongst healthcare providers and researchers. 

Depending on the formulation, the most common side effect of minoxidil is skin irritation near the application site. After using minoxidil, you may notice that your skin feels itchy or sore, has signs of a rash or takes on a slight burning sensation.

This can be a reaction to the minoxidil itself or a reaction to some of the substances commonly used in minoxidil formulas. 

Many minoxidil sprays and foams contain ingredients like propylene glycol and alcohol. These ingredients are usually included to help minoxidil dissolve properly and improve absorption into your skin.

If your skin is sensitive to propylene glycol, alcohol or both substances, you may notice irritation after applying minoxidil topically.

For most people, skin irritation from minoxidil is mild and transient. If you get persistent irritation after using minoxidil, you may want to talk with your healthcare provider about factors that could cause an allergic reaction. 

Your healthcare provider can perform a patch test -- a type of test that’s used to determine what type of substance is irritating your skin -- to see if you’re prone to allergic contact dermatitis from one of the ingredients in your minoxidil foam or topical solution.

If you’re allergic to a specific ingredient in minoxidil, your healthcare provider may suggest using a different formulation that’s less likely to cause irritant contact dermatitis.

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Less Common Side Effects of Minoxidil

In addition to skin irritation, minoxidil can also cause other side effects. These include temporary increased hair loss, as well as unwanted hair growth that may affect your face or other areas of skin exposed to minoxidil.

In some cases, minoxidil may also cause acne breakouts, red bumps that develop on your skin, facial swelling and headaches. 

One of these side effects -- a temporary increase in hair shedding -- can happen as a side effect of minoxidil’s effects on your hair growth cycle.

Minoxidil causes your hairs to prematurely enter the anagen phase of the hair growth cycle -- a phase in which your hair grows to its full length. It does this by shortening the telogen phase, in which hairs stop actively growing and detach from your scalp.

By shortening the telogen phase, minoxidil may cause your hairs to shed all at once as they’re prematurely moved into the first phase of their next growth cycle. 

This can result in temporary hair shedding that gives your hair a thinner appearance, with less coverage of your scalp than normal. This effect is temporary, and your hair will usually regain its previous thickness and coverage level over the course of a few weeks.

If you notice that your hair looks slightly thinner than usual shortly after starting treatment with minoxidil, don’t panic. Instead, wait for three to four months, which is the usual amount of time required to assess the efficacy of minoxidil.

Over time, you should notice that any temporary shedding from minoxidil reverses, with newer hairs filling in thin, low-density areas of your scalp. 

Because minoxidil helps to stimulate hair growth, it may cause unwanted hair growth, including body hair growth, if it’s applied to your face and/or body. In fact, some people use minoxidil to stimulate beard growth to take advantage of this side effect.

To prevent any unwanted hair growth from minoxidil, make sure to only apply this medication to your scalp. Wash your hands thoroughly after you apply minoxidil and carefully wash away any excess solution that makes its way onto your forehead, neck or other areas close to your hair.

Unlike other medications for hair loss, minoxidil isn’t associated with any sexual side effects -- a topic we’ve covered in more detail in our guide to minoxidil and erectile dysfunction

Minoxidil Side Effects From Excessive Use

When it’s used as directed, minoxidil is unlikely to cause significant issues. However, some side effects may develop if you use minoxidil excessively, such as by applying it more than two times per day or using too much minoxidil on your scalp at once. 

Potential adverse effects from excessive minoxidil use include:

  • Dizziness and/or lightheadedness

  • Swelling that affects your face, ankles, stomach or hands

  • Changes in your body weight, such as weight gain

  • Difficulty breathing when you’re lying down

  • Chest pain and/or a rapid heartbeat 

If you notice any of these adverse reactions after using minoxidil, it’s important to contact your healthcare provider for assistance. 

Rogaine Side Effects

Minoxidil is available as a generic medication and under the brand name Rogaine®. Rogaine is sold in a variety of strengths to treat hair loss in men and female pattern hair loss, a form of hair loss that can occur in women.

Generic minoxidil and brand-name Rogaine contain the same active ingredient. This means that their side effects are generally identical. If you’re prone to side effects from generic minoxidil, it’s likely that you’ll experience the same issues from brand-name Rogaine.

Like most forms of generic minoxidil, brand-name Rogaine contains secondary ingredients such as propylene glycol and alcohol. These ingredients may cause irritation, making it important to be careful not to get them in your eyes, mouth or on sensitive areas of skin. 

Brand-name Rogaine can also cause other common side effects of minoxidil, such as unwanted growth of your facial or body hair, acne, swelling around your face and mild hair shedding during the first few weeks of use.

As such, you’ll want to follow the same precautions with brand-name Rogaine as you would with a generic topical minoxidil solution or foam. 

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Minoxidil Drug Interactions

When you hear a commercial for a new drug, you may have noticed that it usually wraps up with a seemingly endless list of potential interactions and side effects.

One significant strong point of minoxidil is that it isn’t known to cause any drug interactions. This means that you can use minoxidil to treat hair loss with plenty of confidence in its safety, even if you’re currently prescribed other medications. 

With this said, minoxidil is contraindicated in people who’ve experienced an allergic reaction to it at any point in the past. Some clinicians also suggest monitoring your blood pressure levels and heart rate while you’re using it, particularly if you have any underlying medical conditions.

As always, even though minoxidil is available over the counter, it’s best to talk to your healthcare provider before using it to make sure you’ll stay safe and healthy during treatment.

Is Minoxidil Safe?

Minoxidil is a safe, widely used medication, with numerous large-scale studies showing that side effects are uncommon.

For example, one review published in the journal Drug Design, Development and Therapy noted that minoxidil is generally considered an “effective and safe” treatment for hair loss.

A separate study, which was published in the Journal of the American Academy of Dermatology, looked at the effects of minoxidil in men with pattern hair loss over a total treatment period of 48 weeks.

The researchers found that the medication was well tolerated, without any evidence of systemic effects.

In short, research shows that minoxidil is safe and effective -- something that’s backed up by the fact that millions of men around the world apply it on a daily basis to stop hair loss and stimulate new hair growth. 

Minoxidil and Pets

One point about minoxidil that’s important to note is that it can potentially be highly toxic for cats, as they lack the specific enzymes that are required to metabolize and excrete minoxidil from the body. 

Minoxidil-related injuries to cats, dogs and other pets are generally rare, but it’s still important to be careful if you have a pet and store minoxidil in your home.

If you have a pet cat or dog, make sure that you do not ever apply minoxidil directly to its skin or fur. Use minoxidil spray or foam in an isolated area, such as your bathroom, with your pet inside a different room. Carefully wash any clothes or pillowcases that are exposed to minoxidil. 

Finally, when you store minoxidil, make sure to keep it inside a sealed container in an area that your pets can’t access. 

Should You Take Finasteride When Using Minoxidil?

Finasteride is a prescription medication for hair loss. Unlike minoxidil, which promotes improved blood flow and speeds up your hair’s growth cycle, finasteride works by stopping your body from creating the hormone dihydrotestosterone (DHT).

DHT can attach to receptors inside your scalp and damage your hair follicles, gradually reducing your average hair diameter and contributing to male pattern baldness.

Our guide to DHT and male pattern hair loss goes into greater detail about the effects of DHT on your hair follicles, as well as how medications like finasteride prevent DHT-related damage.

If you currently use minoxidil for hair loss, taking finasteride at the same time can enhance your results and help you to maintain more of your hair. It may also cause improvements in your hair regrowth.

In a study published in the journal Dermatologic Therapy, researchers found that finasteride and minoxidil were more likely to produce hair-related improvements when they were used together than when either drug was used on its own. 

In the study, 59 percent of men with hair loss who used minoxidil on its own and 80.5 percent of men who used finasteride showed improvements after 12 months of treatment. In comparison, 94.1 percent of men who used both medications showed improvements after 12 months.

If you currently use minoxidil, adding finasteride to your hair loss prevention routine could result in a bigger reduction in hair loss and a better hair regrowth rate. 

We offer finasteride online, following a consultation with a licensed healthcare provider who will determine if a prescription is appropriate.

We also offer a topical finasteride and minoxidil spray that you can use to apply both treatments simultaneously, without having to worry about taking a daily tablet. 

How to Use Minoxidil Properly

Minoxidil is a simple medication to apply -- a topic we’ve covered in lots of detail in our guide to applying minoxidil for hair growth. We’ve included the short and sweet version of how to get the best result while using minoxidil below. 

If you use minoxidil topical solution, follow these steps:

  • Make sure that your hair is completely dry.

  • Fill the dropper with 1mL of minoxidil solution.

  • Apply the minoxidil to the affected areas of your scalp.

  • Using your fingers, gently massage the minoxidil solution into your scalp.

  • Wash your hands thoroughly using soap and warm water.

If you use minoxidil foam, follow these steps:

  • Make sure your hair is completely dry.

  • Dispense half a cap’s worth of foam onto your fingers.

  • Massage the foam into areas of your scalp with noticeable hair loss.

  • After you finish, wash your hands thoroughly with soap and warm water.

After you’ve applied minoxidil to your scalp, allow at least four hours for the medication to dry before covering or washing your hair. 

It’s also important to know that minoxidil can stain clothing or linen, so make sure to wash your hands thoroughly -- and ensure the solution or foam has dried fully -- before you let your hands or scalp touch any type of fabric. 

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The Bottom Line on Minoxidil for Hair Loss

Minoxidil is generally a safe and effective medication -- one of many reasons it’s available over the counter, without any need for a prescription. Every year, millions of people use minoxidil to stimulate hair growth and prevent androgenic alopecia, all without any major issues. 

However, like all medications, minoxidil can still cause side effects, especially when it’s used on an overly frequent basis or without proper care and attention.

If you’re prescribed minoxidil and notice side effects, make sure to let your healthcare provider know as soon as you can. They’ll be able to give you expert medical advice about how you can use minoxidil safely.

Interested in using minoxidil, finasteride or other medications to stop hair loss and increase your hair count? We offer a range of evidence-based hair loss medications online, including minoxidil solution, minoxidil foam and finasteride.

You can also purchase minoxidil and finasteride together as part of our Hair Power Pack, which is available following an online consultation with a physician who will determine if a prescription is appropriate. 

9 Sources

Hims & Hers has strict sourcing guidelines to ensure our content is accurate and current. We rely on peer-reviewed studies, academic research institutions, and medical associations. We strive to use primary sources and refrain from using tertiary references.

  1. Badri, T., Nessel, T.A. & Kumar, D.D. (2021, December 19). Minoxidil. StatPearls. Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK482378/
  2. Rundegren, J. (2004). A one-year observational study with minoxidil 5% solution in Germany: results of independent efficacy evaluation by physicians and patients. Journal of the American Academy of Dermatology. 50 (3), 91. Retrieved from https://www.jaad.org/article/S0190-9622(03)03692-2/fulltext
  3. Suchonwanit, P., Thammarucha, S. & Leerunyakul, K. (2019). Minoxidil and its use in hair disorders: a review. Drug Design, Development and Therapy. 13, 2777-2786. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6691938/
  4. Minoxidil Topical. (2017, November 15). Retrieved from https://medlineplus.gov/druginfo/meds/a689003.html
  5. Women’s Rogaine®. (n.d.). Retrieved from https://www.accessdata.fda.gov/drugsatfda_docs/label/2015/019501Orig1s029lbl.pdf
  6. Olsen, E.A., et al. (2002, September). A randomized clinical trial of 5% topical minoxidil versus 2% topical minoxidil and placebo in the treatment of androgenetic alopecia in men. Journal of the American Academy of Dermatology. 47 (3), 377-385. Retrieved from https://pubmed.ncbi.nlm.nih.gov/12196747/
  7. Zito, P.M., Bistas, K.G. & Syed, K. (2022, May 8). Finasteride. StatPearls. Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK513329/
  8. Ho, C.H., Sood, T. & Zito, P.M. (2021, November 15). Androgenetic Alopecia. StatPearls. Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK430924/
  9. Hu, R., et al. (2015). Combined treatment with oral finasteride and topical minoxidil in male androgenetic alopecia: a randomized and comparative study in Chinese patients. Dermatologic Therapy. 28 (5), 303-308. Retrieved from https://onlinelibrary.wiley.com/doi/abs/10.1111/dth.12246

This article is for informational purposes only and does not constitute medical advice. The information contained herein is not a substitute for and should never be relied upon for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment. Learn more about our editorial standards here.