How Long To Stay Out Of Sun After PDT (And Why)?

Exact Answer: Two To Three Days

PDT stands for Photodynamic Therapy. It falls under the category of phototherapy that involves a photosensitizing chemical substance and light, used in conjunction with oxygen in the molecular form to elicit cell death, scientifically termed phototoxicity. The therapy is widely used for treating acne issues all around the world.



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PDT has various advantages and the biggest one being that the therapy lessens the need for minimal formation and lengthy recovery, and delicate surgery of disfigurement and scar tissue. Photosensitisation of skin cells is an adverse side effect of the therapy. The therapy is also referred to as Photochemotherapy.

How Long To Stay Out Of Sun After PDT?

PDT is widely used for treating many medical conditions, including psoriasis, age-related macular degeneration, atherosclerosis, and is also very efficient in anti-viral treatments, such as herpes and a few others. The therapy is also helpful in treating malignant cancers, including lung, head and neck, bladder, and particular parts of the skin. The technology has also proved vital for treating prostate cancer in prostate cancer patients. The therapy is minimally toxic and minimally invasive. Hence, this treatment is recommended by medical experts globally.

PDT is also an excellent method to cure blood-borne microbes and viruses as it is beneficial in sterilizing water and blood plasma. Photosensitizers are also recommended for various agricultural purposes, including insecticides and herbicides. The therapy is also used in multiple ophthalmology treatments by doctors. Photosensitizers are also known for naturally accumulating in the endothelial cells in various vascular tissues. This helps perform vascular-targeted PDT. It is also widely used in Photoimmunotherapy.

Age Group Of The PatientTime After PDT To Stay Out OF Sun
MinorThree days
AdultTwo days

It is advised not to go directly into the sunlight after the therapy. Medical professionals believe that an adult should avoid facing direct daylight for a minimum of two days after completing the treatment. In contrast, a minor should wait three days after the therapy to go into the sunlight. The treatment takes longer to heal in minors than adults as a minor’s body cells are still developing.

Why Does It Take That Long After PDT To Stay Out Of Sun?

PDT involves three components, namely a photosensitizer, tissue oxygen, and a light source. It is made sure that the wavelength selected for the light source is appropriate enough for the excitation of the photosensitizer. Appropriate excitation leads to the production of reactive oxygen species or radicals.

The free radicals are generated by electron transfer or abstraction from a substrate molecule. The molecule is generally singlet oxygen that is the higher reactive state of oxygen. The therapy is a multi-stage process, and it requires a lot of precision to complete the treatment correctly.

Doctors recommend not going into the sunlight after completing the therapy as Sunlight can result in the reactivation of the medicine and can cause a severe sunburn on the skin. It is advised not to apply any makeup or use any ointments on the skin to be treated. The patient must make sure to bring black clothes and sunglasses to wear after the treatment. It is advised to consult an authentic medical expert for this purpose.

The patient must wash the part of the skin which will be treated beforehand. It is also advised to wear thick cotton clothes on the treatment area while washing the face or bathing. The patient must follow all the instructions provided by the doctor for accurate results. Negligence towards the body can prove harmful and can nullify the effort put in during the treatment.


Finally, it can be concluded that PDT is a shorthand used for the term Photodynamic therapy, and it is widely used to treat various skin issues. The treatment is also very useful in treating cancers and a few other medical conditions. It is also used in anti-viral treatments in different parts of the world.

On average, a person must avoid going into direct sunlight after the therapy for a minimum of two days. Facing sunlight can lead to severe sunburn and can prove to be harmful. It is crucial to consult an authentic medical expert in such cases as skin treatments are susceptible.


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