Guide for teeth whitening. The antibiotic tetracycline causes gray teeth in children whose teeth are still developing. Antibacterial mouthwashes that contain chlorhexidine or cetylpyridinium chloride can also stain teeth. Some antihistamines, antipsychotic drugs, and blood pressure medications cause tooth stains, as can iron and excess fluoride. If bleaching doesn’t help, ask your dentist about dental […]