Tetracycline Phototoxic or Photoallergic Reactions

[Guide]

Tetracycline has been used to treat rosacea for a long time, particularly doxycycline. One of side effects is photosensitivity. The article below distinguishes between a phototoxic or a photo allergic reaction. 

"Tetracyclines (TCs) are a group of broad‐spectrum antibiotics discovered in the 1940s and exhibited activity against a range of microorganisms including gram‐positive and gram‐negative bacteria (e.g., chlamydiae, mycoplasmas, rickettsiae), and protozoa; they are largely prescribed in dermatology and infectious diseases, both for the anti‐bacterial and anti‐inflammatory actions. TCs are considered generally well tolerated, although some adverse events may occur during treatment, one of them is photosensitivity. From the photobiological point of view, the photosensitivity reactions are a consequence of the absorption of light energy by a photosensitizing substance (e.g., a drug) and of the subsequent photochemical reactions determining changes in living tissues. They are usually divided in phototoxic or photoallergic, depending on the different mechanism involved. TCs have been reported as phototoxic, but not photoallergic drugs."

Tetracyclines and photosensitive skin reactions: A narrative review