On 30mg lanzoprazole and 10mg omeprazole. What are potential side effects?

PPI's. It is unusual for someone to be on two of the same class of medications at the same time. Was this prescribed this way or did you just take it on your own? Generally PPIs are relatively safe. Short term they have very few side effects. Long-term there are some concerns over kidney, electrolytes, and possible pneumonia risks. Talk to your doctor to manage this. Good luck.