How Long Does Redness Last After PDT (And Why)?

How Long Does Redness Last After PDT (And Why)?

Exact Answer: 3 to 10 days 

PDT, in medical terms, is an abbreviation of photodynamic therapy. Light energy is the critical component used in this therapy. The treatment combines the use of light energy and photosensitizer, which is a drug. The drug can be injected into blood veins or put on the skin depending upon the application. PDT is used to destroy cancerous and precancerous cells, thereby removing the illness. 

This therapy was first used in the early 1990s. However, recently the technology is modernized, and it only destroys targeted cells. But there may occur some side effects, although not permanent. People who undergo this therapy on the skin may experience redness and irritation. 

How Long Does Redness Last After PDT

How Long Does Redness Last After PDT 

The after-effects of any treatment will vary from person to person. It is true even in the case of Photodynamic Therapy. Some people are sensitive to PDT. So they may receive less treatment than others. However, most people tend to heal faster while undergoing therapy. Once a person has taken PDT, he may experience side effects on the early onset. They include pain, Immunosuppression, Urticaria, etc.

 While undergoing therapy on the skin, we may experience skin-related issues like redness, itching, or pain. It takes some time to recover from these issues depending upon the immunity of a person. As we know, the healing of any disease depends on how strong our immunity is. The side effects also last longer if we are not immune. 

One can expect the redness, swelling of the skin, or peeling after 2 or 3 days after undergoing treatment. We may also experience fever during this time. These symptoms can be reduced by taking care of ourselves. The photosensitizer makes the treated part sensitive to light. 

Generally, Photodynamic Therapy is a two-stage treatment used to destroy cancer cells. As this therapy uses light energy, it causes the skin to become sensitive. A photosensitizer acts as a toxic material for the targeted cells. 

face infection
Side Effects Time Taken to Recover
Burning24-48 Hours
Redness and Swelling1 Week
Scaling or Crusting4 Weeks

Why Does Redness Last That Long After PDT 

After undergoing PDT, one can experience redness, itching, or swelling of the skin. We can also observe the swelling of the eyes and lips. Some patients may experience mild side effects, while persons with sensitive skin may experience severe results. Usually, the treatment will be conducted in two or three stages to get effective results.  

Photodynamic therapy can be performed by using any of the wavelengths of light depending upon the application. Some light-based treatments are laser, blue light therapy, sauna light UV rays, and so on. Some of them may be harmful to the skin in the long run. However, few of the treatments may also show side effects within days after treatment.  

Photodynamic Therapy can be repeated in the same area many times if a similar problem still exists. It can get rid of the targeted cells very precisely when compared to other modes of treatment. So it can have side effects as the treatment time is significantly less. Care is to be taken by the person who has undergone the PDT. He should avoid exposure to sunlight or normal light for a few days.

face infection

The side effects of the PDT last for a duration of time. It all depends upon the affected area and whether the person can be insensitive to the treatment. Swelling or redness lasts for a few days to reduce the harmful effects of the treatment. It can also affect the immune system in some persons who are very sensitive to the changes in the body. 


The person who undergoes PDT should be cautious and avoid any exposure to light. While going out, sun cream and full-length clothes are to be applied. The person may also be required to not over-treat the swelling or red area on the skin as it can last only for a few days. 

PDT can only be used on parts that the skin can reach as the light penetrates the skin and kills the targeted cells. The light can only penetrate for a certain distance of the tissue. Hence for too large areas having cancer or parts which can not be reached by light cannot be treated by this therapy. 


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Hi! I'm Nidhi.

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  1. The science behind PDT is quite complex, but the article explains it well. It’s reassuring to know the treatment is so targeted.

  2. Considering all the information set out in the article, I think the effectiveness of PDT outweighs the temporary side effects.

  3. The amount of time it takes to recover from PDT side effects is a small price to pay for the treatment benefits. It’s important that people understand that.

  4. I’m honestly surprised that people still doubt the effectiveness of PDT. It’s a proven treatment method, and any side effects are temporary.

  5. PDT is, without a doubt, a great scientific advancement. The side effects are worth it if it means you can remove cancerous or precancerous cells.

  6. It’s important for those who have undergone PDT to take the necessary precautions to avoid complications during recovery. This post is very informative.

  7. This post is very informative. Just because something has side effects doesn’t mean it isn’t effective. It’s always worth considering the benefits versus the costs.

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