Which tetracycline is known to cause a blue sclera?

• A. Tetracycline
• B. Doxycycline
• C. Minocycline
• D. Demeclocycline

Answer: (C)

Minocycline is known to cause blue scleral discoloration because the drug and its metabolites can deposit in ocular tissues, leading to a blue-gray pigmentation of the sclera. Its greater lipophilicity and tissue penetration allow pigment to build up in the sclera over time, especially with long-term or high-dose use. This effect is more characteristic of minocycline than other tetracyclines, which is why the blue sclera is associated with minocycline. The discoloration can persist after stopping the medication, and while other tetracyclines may cause teeth staining or photosensitivity, blue scleral pigmentation is not a common feature for them.