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

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 dealing with the effects of male pattern baldness.

Like all medications, minoxidil has both primary effects and side effects. For most people, the side effects of minoxidil are relatively minor. 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.

What Are The Side Effects of Minoxidil?

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

Depending on the formulation, the most common side effect of minoxidil is skin irritation at or near the application site. In some cases, minoxidil users can develop a skin rash or experience a mild burning feeling after using minoxidil spray or foam.

This can be a reaction to the minoxidil itself or a reaction to some of the substances commonly used in minoxidil formulas. Many minoxidil products contain propylene glycol, and alcohol, which can lead to skin rash and irritation when applied topically.

Other, less common side effects of minoxidil include:

  • Acne
  • Facial hair growth
  • Inflammation around the hair roots
  • Facial swelling
  • Increased hair loss

These side effects are relatively uncommon and do not affect most minoxidil users. Increased hair loss, one of the most publicized side effects of minoxidil, is often the result of hair follicles rapidly moving through the hair growth cycle and shedding before an anagen phase. This is normal as it is part of the mechanism in how minoxidil works.

There are also side effects of minoxidil that can occur from excessive use of the medication. In most cases, these side effects occur when too much minoxidil is applied at once, resulting in an overly high level of minoxidil being absorbed into the body. These side effects include:

  • Dizziness
  • Lightheadedness
  • Fainting
  • Irregular heartbeat
  • Chest pain
  • Headaches
  • Flushing
  • Blurred or altered vision
  • Numbness of the face, hands, and feet
  • Swelling of the face, hands, feet, and legs
  • Rapid weight gain

If you notice any of these side effects after taking minoxidil, the best course of action is to speak to your doctor as soon as possible.

Are Minoxidil Side Effects Common?

Minoxidil is a safe, widely used medication, with numerous studies indicating that side effects are uncommon:

Of the side effects of minoxidil, the most common is skin irritation in and around the area where the spray or foam is applied. This usually reverses and heals by stopping the minoxidil.

Millions of men around the world use minoxidil on a daily basis to prevent hair loss and improve hair growth. On the whole, side effects are rare and minoxidil is viewed as one of the safest hair loss treatments on the market today.

Minoxidil and Pets

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

According to the ASPCA, there were six cases between 2001 and 2014 of cats being negatively affected by exposure to minoxidil. Of these, four cats have died after exposure, while the others required aggressive treatment in order to survive.

If you have a pet cat, make sure you do not ever directly apply minoxidil to its skin or fur. Use the minoxidil spray or foam in an isolated area (such as a bathroom, with your cat in a separate room) and keep minoxidil products stored inside a safe area that’s out of reach of your pets.

This article was reviewed by Ho Anh, MD.

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.