For which of the following should tetracycline antibiotics be avoided in children under 8?

Tetracycline antibiotics should be avoided in children under 8 primarily due to the risk of teeth discoloration. These antibiotics can bind to calcium ions in developing teeth, leading to irreversible changes in tooth color—often manifesting as yellow, gray, or brown staining. This effect on tooth enamel occurs when the medication is administered during the period of active tooth development, which is particularly critical before the age of 8 when permanent teeth are still forming.

While growth problems is a concern that may arise with long-term use of some antibiotics, the direct and visually impactful consequence of tetracyclines on a child's dental health is the primary reason for their avoidance in this age group. Nausea and skin rashes can occur with various medications, including tetracyclines, but these are not specific or as significant as the risk of discoloration of the teeth. Thus, the most compelling reason to avoid tetracycline antibiotics in young children is the potential for teeth discoloration.