What Is Drug-induced Photosensitivity?

It is estimated that around 3,000 drugs can cause photosensitivity reactions. What does this problem consist of? What are the symptoms? Read this article to discover everything you need to know.
What is drug-induced photosensitivity?

Drug-induced photosensitivity is quite common. In fact, researchers estimate that around 3,000 medications may cause this effect. It can appear as a phototoxic or a photoallergic reaction.

Therefore, all phototoxic or photoallergic reactions are photosensitivity reactions, but not all photosensitivity reactions are either phototoxic or photoallergic. All of these are abnormal reactions that occur on the skin after sun exposure and after taking certain medications.

In the summer, it is especially important to be careful with this type of problem. For this reason , both healthcare professionals and patients should be informed about what these medications are and what reactions they may cause.

What is drug-induced photosensitivity?

As we mentioned above , this condition is a skin reaction that occurs when the sun’s rays hit the skin and interact with chemical compounds in photosensitive medicine.

These compounds, which react with the light spectrum between visible light and ultraviolet radiation, can be both the active ingredient and one of the excipients which are part of the formula.

It is worth mentioning that photosensitivity reactions account for 8% of all side effects, and skin pigmentation is among the risk factors. The more pigmented it is, the greater the likelihood of suffering from these reactions.

In addition to pigmentation, other population groups are exposed. Among them we find the following:

  • Patients being treated with NSAIDs for chronic pain.
  • Cancer patients being treated with chemotherapy.
  • People with a psychiatric illness who are being treated with phenothiazines.
  • Patients with high blood pressure taking thiazides as treatment.
  • Finally, elderly people and patients with weak immune systems.
A person taking medication
Drug-induced photosensitivity manifests itself with symptoms similar to sunburn.

What is a phototoxic reaction?

As we mentioned earlier, a phototoxic reaction is a type of drug-induced photosensitivity reaction. Unlike a photoallergic reaction, which we will look at later, the immune system does not play a role in a phototoxic reaction.

Phototoxic reactions represent 95% of all drug-induced photosensitivity reactions. They may develop a few minutes or hours after taking the drug and the main symptoms are as follows:

  • Erythema and edema
  • Itchy blisters
  • Symptoms similar to severe sunburn

These reactions are more common with orally administered drugs and develop because they create free radicals that interact with oxygen, resulting in highly reactive and cell-damaging chemicals.

What is a photoallergic reaction?

This is another type of photosensitivity reaction. In this type of reaction, as we mentioned above, the immune system is involved. To trigger a photoallergic reaction, UV rays must cause a chemical transformation of the medicine administered.

The medicine is transformed into another chemical called hapten, which interacts with skin proteins and eventually triggers an immune reaction.

Among the most common symptoms , we have examinative inflammation if the medicine was taken orally or a rash in cases where it has become topical.

A woman scratching her arm
The immune system is involved in photoallergic reactions. The lesions are eczematous.

What are the medications that can cause drug-induced photosensitivity?

Many medications can have these types of reactions. Therefore, you should always check the technical specifications of the medicines to know if they are photosensitive or not.

However, we will provide a brief list of some of these medications. Of course, remember that there are many more, so you should always consult your doctor or pharmacist.

  • Antimicrobial drugs such as tetracyclines, cephalosporins or tuberculosis drugs.
  • Cardiovascular drugs: thiazides, ACE inhibitors or statins
  • Hypoglycemic medicines, which are medicines that reduce glucose levels
  • NSAIDs or Non-Steroidal Anti-Inflammatory Drugs
  • Retinoids
  • Psychopharmaceuticals
  • Chemotherapeutic agents
  • Antihistamines

The key is to learn about medication

It is important to stay informed about the side effects that medications can cause. To do this , read both the package leaflet and technical documents and consult your doctor. Drug-induced photosensitivity reactions are actually common, and it is very important to know what your triggers are in order to prevent them.

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