Gastric bypass and medication: what changes in absorption

Which medicines are actually affected

Most medicines still work after a gastric bypass, but three groups need reviewing before you travel: extended-release tablets, anti-inflammatories, and anything with a narrow margin between the effective and the toxic dose. The reason is simple geometry. The tablet now meets a small pouch and a shortened absorptive path, so a capsule designed to release its content over eight hours may have passed through before it has finished releasing anything.

Anti-inflammatories: the one permanent rule

Ibuprofen, diclofenac, naproxen and aspirin taken as a painkiller come off the list permanently after a bypass. They erode the lining at the join between pouch and intestine, and a marginal ulcer there is painful, slow to heal and occasionally needs further surgery. Paracetamol is fine. If you have a condition that genuinely requires long-term anti-inflammatories, we will usually recommend a sleeve instead of a bypass, and we say so at the consultation.

Forms to switch, and what to ask your own doctor

Extended-release, enteric-coated and physically large tablets are swapped for immediate-release, liquid or crushable forms during the first three months while the pouch is small. Thyroid replacement, antidepressants, epilepsy medication, warfarin and diabetes drugs all need their blood levels or doses rechecked afterwards rather than assumed. We write to your prescribing doctor with the operation details, because whoever monitors your bloods at home should not be learning this from you.

Diabetes and blood pressure doses drop fast

This is the change nobody warns patients about. Insulin and oral diabetes drugs often need reducing within days of a bypass, sometimes before you leave hospital, and blood pressure tablets follow over the first weeks. Continuing the old dose into a body that no longer needs it causes hypoglycaemia and dizzy spells at exactly the moment you are travelling. We plan the taper in writing and hand it to your own doctor from month two.

The Ones People Actually Ask.