Tetracyclines are a class of broad-spectrum antibiotics that inhibit bacterial protein synthesis by binding to the 30S ribosomal subunit, thereby preventing the attachment of aminoacyl-tRNA to the ribosomal acceptor (A) site.
This action is typically bacteriostatic rather than bactericidal.
The tetracycline class includes: tetracycline, doxycycline, minocycline, and demeclocycline, as well as newer derivatives like tigecycline, omadacycline, and eravacycline.
These antibiotics are effective against a wide range of Gram-positive and Gram-negative bacteria, making them useful in treating various infections, including respiratory tract infections, acne, and certain sexually transmitted infections.
Tetracyclines also exhibit non-antibiotic properties, such as anti-inflammatory and immunomodulatory effects.
However, their use can be associated with side effects, including phototoxicity, gastrointestinal disturbances, and, rarely, drug hypersensitivity reactions.
The American College of Allergy, Asthma & Immunology notes that adverse reactions to tetracyclines, particularly minocycline, are more common than to other tetracyclines like doxycycline, likely due to differences in side-chain structures.
 Additionally, tetracyclines can have lasting effects on bone metabolism, as they are retained in the bone matrix and can disrupt skeletal development.