Possible side effects of Alka-Seltzer effervescent tablets: All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome: Heartburn; nausea; upset stomach.
A myoclonic jerk is the brief, involuntary twitching of a muscle or group of muscles. It may be caused either by a sudden muscle contraction, or a sudden lapse of contraction.
Various myoclonic syndromes. Mycoclonus is a sudden brief, shock-like muscle movement caused by a brief muscle contraction (positive myoclonus) or inhibition of a muscle contraction (negative myoclonus) It can mimic idiopathic drop attacks, and the patient can fall suddenly with buckling of the legs.