The half-life of doxycycline is reduced by concurrent administration of barbiturates or phenytoin.

Simultaneous administration of oral absorbants, iron preparations and antacids should be avoided as they reduce doxycycline availability.

Overdose: the toxicity and tolerance studies have shown that this product is very well tolerated in cats after five times the recommended dose. Raised levels of SGPT, GGT, SAP and total bilirubin were noted in dogs which received three or five times the recommended dose. Some vomiting can occur in dogs with five times the recommended dosage.