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.
These movements are called 'hypnic jerks'. Most people are also familiar with the random body 'shudder' that some people get. This is sometimes described as 'walking on someones grave' because of the way it moves quickly through the body. The occasional hypnic jerk or a body shudder are normal. But in functional myoclonus the jerks become a frequent and disabling problem. There may be jerks of the arms or legs, or quite commonly there is jerking in the body.The movements cannot be controlled (ie they are involuntary)