Do I Need Phototherapy for Acne?

Medically Reviewed by Stephanie S. Gardner, MD on September 18, 2023
Written by WebMD Editorial Contributors
3 min read

Your doctor has a lot of ways to clear up your acne, from creams and gels to chemical peels and antibiotics. But sometimes those breakouts happen anyway.

Phototherapy is an option for stubborn acne that doesn't improve with other treatments. It uses a special type of light to kill the bacteria on your skin that cause acne.

Acne forms in pores -- the tiny holes in your skin. Each pore contains an oil-producing gland. The oil keeps your skin healthy.

But sometimes the oil, dirt, and dead skin cells can get trapped inside pores and clog them up. Bacteria called Propionibacterium acnes (P. acnes) that live on your skin can also get inside these blocked pores. P. acnes make the clogged pores swell up into bumps called acne.

One way to kill bacteria and clear up pimples is with light. The bacteria in your skin are sensitive to certain types of light. When you shine these lights on your skin, toxic substances form and kill the bacteria. Light therapy also shrinks the oil glands in your skin, so your skin makes less pore-clogging oil.

Doctors used to treat acne with ultraviolet (UV) light -- the type of radiation that comes from the sun. UV light clears up acne, but it can also damage the skin and cause cancer. Today, doctors don’t use UV light to treat acne.

Instead, they use certain wavelengths of blue or red light. Blue and red light therapy kills acne-causing bacteria without damaging the skin.

Light therapy works on mild to moderate acne. You get this treatment at your dermatologist's office about once a week.

Your doctor will tell you to stay out of the sun and avoid tanning beds for a week or more before your treatment. You might also have to stop using some of your skin-care products.

You may get special medicine before your treatment to make your skin more sensitive to the light. Doctors call these medicines “photosensitizers.” They include aminolevulinic acid (ALA) and methyl aminolevulinate (MAL).

Photodynamic therapy, or PDT, is light therapy combined with medicine. It clears up acne faster than light alone. But it can also cause more side effects.

During phototherapy, you sit in front of an LED light panel for about 15 to 30 minutes. These lights may be blue, red, or both blue and red.

Phototherapy can bring down swelling and reduce the number of pimples in some people. Studies show blue light therapy clears up acne by nearly 70% within 8 to 10 treatment sessions.

Phototherapy can cause side effects, such as:

  • Pain when the light shines on your skin
  • Redness
  • Swelling
  • Dryness
  • Change in skin color

The medicine used in photodynamic therapy makes your skin very sensitive to light. So you'll have to stay out of the sun for a few days after your treatment to avoid a burn.

Side effects from photodynamic therapy include:

  • Peeling
  • Crusting
  • Rash
  • Dark patches of skin

Light therapy isn't recommended for people who:

You should also avoid photodynamic therapy if you are:

  • Pregnant
  • Allergic to the medicines ALA or MAL

A few home light devices are FDA-approved to treat mild-to-moderate acne. These products use blue light, red light, or both.

A few small studies have shown that home light products clear up acne in many of the people who use them. Their side effects are usually mild, such as dry and red skin.

Everyone's skin is different. Talk to your dermatologist about all of your acne treatment options. Consider the pros and cons of phototherapy before you decide to use it.

If you want to try a home light therapy device, check with your dermatologist first. You want to be sure it's safe for you. The doctor can also make sure that you use it the right way.