What sort of side effects might one experience while taking imuran (azathioprine)?

Mostly none: If you're taking Imuran (azathioprine) at the doses used to teat ibd, most have no side effects. Few are allergic and develop pancreatitis. The biggest issue is to monitor blood counts to make sure WBC doesn't go too low, which can lead to serious infections. Occasionally liver enzymes can go up, which is reversible. Very rarely associated with malignancy. You should have tpmt checked before starting.