Drugs that may cause an elevated GGT level include phenytoin, carbamazepine,
and barbiturates such as
phenobarbital. Use of many other prescription
and non-prescription drugs, including nonsteroidal anti-inflammatory drugs (NSAIDs), lipid-lowering drugs, antibiotics, histamine receptor blockers (used to treat excess stomach acid production), antifungal agents, antidepressants, and hormones such as testosterone, can increase GGT levels.