Which of the following is a common side effect of tetracycline?

Tooth discoloration is a well-documented side effect of tetracycline, particularly when it is administered during the developmental stages of teeth in children or during pregnancy. The tetracycline class of antibiotics can bind to calcium ions in developing teeth and bones, leading to a characteristic yellow, gray, or brown staining of the teeth. This is primarily due to the fact that tetracycline can chelate with calcium, resulting in permanent pigmentation changes.

In contrast, salivary gland swelling and oral ulcers are not typically associated with tetracycline use. While some antibiotics can lead to varying oral side effects, the specific link between tetracycline and tooth discoloration has considerable clinical evidence, making this response appropriate in the context of common side effects associated with this medication.