Blue Light Therapy for Acne

Blue light therapy or photodynamic therapy (PDT) uses a photosensitizing agent that is a drug, which gets activated when exposed to a light source. The light source can be laser lights or visible non-laser lights. Both the drug and lights interact together to kill P.acnes bacteria. The US FDA has approved the use of a narrow-band, high intensity non-laser visible blue light for this therapy that treats inflammatory acne.   The light that is applied measures 405-420nm and does not cause any harm to the skin. 

When the sebaceous glands get infected by the P.acnes bacteria, it produces porphyrins that are chemical by-products of their metabolism. Blue light when it is used, searches for porphyrins found in the bacteria. The intense blue light activates porphyrins that kill P.acnes bacteria. Scientists hope that by using blue light therapy, the sebaceous glands shrink and slow down their production of sebum. 

Blue light therapy is administered by a technician, doctor or nurse. A painless, clear solution called aminolevulinic acid (ALA) is applied to the skin. This solution is a strong, photosensitizing agent that increases the patient’s sensitivity to light. ALA is left for 15-60 minutes depending on the severity of lesions. During this time, it accumulates in the sebaceous glands that are the target cells.

Now, the blue light activates ALA. The activation time is usually 8-10 minutes. Heat is produced during the chemical reaction and P.acnes bacteria get destroyed. You may require several sittings of blue light treatment for it to be effective. Blue light therapy only deals with P.acnes bacteria and this is temporary. It can resurface quickly and require ongoing treatment. 

Light therapies work well along with other acne treatments. They can even help acne lesions that have not responded to other treatments. Results of light therapies are not the same for everyone. There will be some amount of clearing but it will not be 100%. Light therapies do not produce dangerous side effects associated with strong acne medications.  This therapy is also beneficial for those who have acne lesions that have developed resistance to oral antibiotics. 

While people usually get treated in a medical clinic, blue light therapy can even be administered at home. Different models are available costing $190 – $ 300. If the treatment is done at home, there will not be the added cost of doctor’s charges. 

blue light therapy for acne

Possible Side Effects of Blue Light Therapy

All patients will suffer from light sensitivity and must not expose themselves to strong lights for a couple of days after treatment. 

Other side effects of blue light therapy are temporary pigment changes that are mild, dryness and slight swelling and redness of the areas that were treated. 

Blue light devices for home use produce lesser side effectives, since the UV levels in these devices are very low. Only very sensitive people develop irritation or redness. 


If you undergo blue light therapy, you must follow certain precautions after the treatment. Do not go out into the sun. Even a few minutes of exposure can cause severe sunburn and peeling skin. Hence, for at least two days after this therapy, stay way from strong, direct light. If you have to go out, then use the right sun protection on all the treated areas. 

While blue light therapy is effective against mild acne-causing bacteria, it cannot be used for those who suffer from nodulocystic acne that can become worse with this treatment.  Even though light therapies can be undertaken at home, you must not do so without consulting a certified dermatologist.