Mefnol Spas Tablet helps to provide symptomatic relief from menstrual (period-related) pain and cramps. It is also used to treat abdominal pain by relieving spasms of the muscles in the stomach and intestines. It may cause some common side effects like dizziness, dryness in the mouth, blurred vision, nausea, and sleepiness. If you experience any of such side effects that do not go away or get worse, you should let your doctor know. Your doctor may be able to suggest ways of preventing or reducing the side effects.