Serious lansoprazole side effects include skin irritation or rash, blistering skin,
hives, swelling of the face, lips, tongue, throat or eyes. Other serious lansoprazole side effects include breathing problems, difficulty swallowing and hoarseness.
Additional lansoprazole side effects include abnormal, racing or pounding heartbeat and lethargy. Dizziness, lightheadedness, uncontrollable shaking in one area of the body, muscle spasms and seizures are also serious lansoprazole side effects.