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.
A hypnic jerk is an involuntary twitching of a muscle, or muscles (the myoclonus as mentioned above). They usually occur just as youâre falling asleep, during whatâs known scientifically as the hypnagogic state of consciousness.