Mefenamic Acid Side Effects. Did you ever experience having constipation or diarrhea after you took in mefenamic acid? According to the National Institututes of Health both conditions are two of the common side effects of the non-steroidal anti-inflammatory drug marketed as Ponstan, Ponstal, Dolfenal and a lot of other brand names*.
Other side effects listed for mefenamic acid are gas or bloating, headache, dizziness, nervousness, and ringing in the ears. Should you experience any of the aforementioned side effects and if the symptoms are severe and would not go away, you should contact your doctor as soon as possible.