Resteclin 250 Capsule is used to treat bacterial infections. It is also used to treat sexually transmitted diseases, such as syphilis, gonorrhoea, or chlamydia. It contains Tetracycline, which inhibits bacterial growth. It may cause common side effects such as nausea, vomiting, diarrhoea, loss of appetite, mouth sores, black hairy tongue, sore throat, dizziness, headache, and rectal discomfort. Before taking this medicine, you should tell your doctor if you are allergic to any of its components or if you are pregnant/breastfeeding, and about all the medications you are taking and pre-existing medical conditions.