Aim and objectives: To study the prescribing pattern of antibiotics used in emergencies in a tertiary care hospital.To study the frequency of antibiotic related ADRs experienced in critical care unit. Methods: This study is an observational prospective study which was done by collecting data from case sheets of patients who have developed adverse drug reactions against antibiotics in a critical care unit in a Government Thoothukudi hospital. Ethical clearance approval was done by institutional ethical committee. Results: This study found that nearly 75% of ADRs are type B reactions. Most of the ADR’s are cutaneous. The data presented here shows that there is increased reaction for cephalosporins. Drug surveillance can strongly identify targeted adverse events. Hence, the pattern of antibiotics and the prevalence of ADR in emergency are described. Conclusion : This study also motivates the Doctors to report the ADR’s, so that we, Doctors can be aware of those and make us ready to tackle the situation. Further elaborative clinical studies required to potentiate this claim.