Which serious side effect is associated with tetracyclines?

The serious side effect associated with tetracyclines is teeth staining. Tetracyclines are a class of antibiotics known to bind to calcium in developing teeth and bones, which can lead to permanent discoloration if they are administered to children whose teeth are still developing. This side effect is particularly concerning for pediatric populations and pregnant women due to the potential impact on the fetal development of teeth. Tetracyclines are contraindicated in children under eight years of age and in pregnant or nursing women for this reason, highlighting the importance of understanding the long-term implications of the medication on dental health.

While the other choices represent various medical conditions or symptoms, they are not directly linked to the use of tetracyclines as a notable side effect.