Why is doxycycline typically contraindicated in children?

• A. It can cause tooth discoloration and weakened dental enamel
• B. It causes liver toxicity
• C. It causes growth plate shortening
• D. It causes renal failure

Answer: (A)

During tooth development, doxycycline is incorporated into calcifying teeth because it chelates calcium, leading to permanent tooth discoloration and enamel hypoplasia. This effect is most pronounced in children whose teeth are still forming, typically under eight years old, which is why doxycycline is avoided in that age group. In adults with fully formed dentition, this risk does not apply. The other listed concerns—liver toxicity, growth-plate effects, or renal failure—are not the primary factors behind this pediatric contraindication.