I'm looking at a site which lists the possible side effects of the medication , Lisinopril .
Amongst other things, Indegestion and Heartburn is listed as possible side effects .
However looking at the combination drug , Lisinopril & Hydrochlorothiazide - heartburn and indegestion is not listed
Clopidogrel could be a more likely culprit, BUT it is a big mistake to assume that certain symptoms are due to drug therapy, even if the instructions in the packet name those side effects.
The bottom line here is, if your "indigestion" is not being relieved by your Gaviscon, within a fortnight at the latest, then i would advice you to see your doctor who may well instigate further investigation.