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.
1 Action myoclonus is characterized by muscular jerking triggered or intensified by voluntary movement or even the intention to move. 2  It may be made worse by attempts at precise, coordinated movements. 3  Action myoclonus is the most disabling form of myoclonus and can affect the arms, legs, face, and even the voice.