Barbiturates, phenytoin and rifampin (drugs that induce liver enzymes) can increase betamethasone metabolism, therefore dose adjustment needs to be done if these therapy are given simultaneously. Concomitant administration with ulcerogenic drugs eg, indomethacin can decrease peptic/intestinal ulcer risk. Also, co-administration with aspirin in hypoprothrombinemia patients should be done carefully. In polyarthritis patients, concomitant administration with salicylates should be done carefully, adverse effects should always be monitored. Diuretics (thiazides, furosemide, ethacrynic acid) and other drugs which promotes potassium loss causes excessive betamethasone effect on potassium, therefore serum potassium should always be monitored. In myasthenia gravis patients, anticholinesterase drugs should be stopped at least 24 hrs before betamethasone administration is initiated. Immunization in patients taking betamethasone needs serological test to assure appropriate antibody response and vaccine/toxoid dose may increase. Central nervous system depression may be exacerbated when given simultaneously with other depressants eg, barbiturates, tranquilizers and alcohol; physicians should not give these drugs to avoid overdose and patients should be informed not to consume alcohol. MAOI can elongate and magnify antihistamine effect.