Tetra Bolus Tablet is used to treat bacterial infections. It contains Oxytetracycline hydrochloride, which belongs to the class of antibiotics. It works by destroying the outer protein layer (cell wall) of bacteria, thereby killing the bacteria (bactericidal). It may cause side effects such as rash, vomiting, allergic reaction, fever, headache, cramps, feeling sick, sore throat, tiredness, stomach pain, nausea, and diarrhoea.