Which antibiotic class is associated with teeth discoloration and photosensitivity?

• A. Fluoroquinolones
• B. Tetracyclines
• C. Macrolides
• D. Aminoglycosides

Answer: (B)

Tetracyclines have two well-known adverse effects that stand out for this question: teeth discoloration and photosensitivity. Teeth staining occurs when the drug is present during tooth development; it chelates calcium and becomes deposited in dentin and enamel, creating intrinsic yellow to gray-brown discoloration that can persist long after therapy, which is why they're avoided in young children and in pregnancy. Photosensitivity happens because tetracyclines absorb ultraviolet light and can generate reactive species in the skin, leading to exaggerated sunburn or rash with sun exposure. Doxycycline is a common example of this effect, so patients are advised to use sun protection. Other antibiotic classes may cause photosensitivity but do not cause the characteristic tooth discoloration seen with tetracyclines, and they lack this staining mechanism.