What side effects may I notice from receiving Mefenamic Acid?

Side effects that you should report to your doctor or health care provider as soon as possible:

-allergic reactions (skin rash, itching or hives; swelling of the face, lips, or tongue)
-bleeding (bloody or black, tarry stools; red or dark brown urine; spitting up blood or brown material that looks like coffee grounds; red spots on the skin; unusual bruising or bleeding from the eyes, gums, or nose)
-heart attack (trouble breathing; pain or tightness in the chest, neck, back or arms; unusually weak or tired)
-heart failure (trouble breathing; fast, irregular heartbeat; sudden weight gain; swelling of the ankles, feet, hands; unusually weak or tired)
-kidney injury (trouble passing urine or change in the amount of urine)
-liver injury (dark yellow or brown urine; general ill feeling or flu-like symptoms; loss of appetite, right upper belly pain; unusually weak or tired, yellowing of the eyes or skin)
-low red blood cell counts (trouble breathing; feeling faint; lightheaded, falls; unusually weak or tired)
-rash, fever, and swollen lymph nodes
-redness, blistering, peeling, or loosening of the skin, including inside the mouth
-stroke (changes in vision; confusion; trouble speaking or understanding; severe headaches; sudden numbness or weakness of the face, arm or leg; trouble walking; dizziness; loss of balance or coordination)
Side effects that usually do not require medical attention (report to your doctor or health care provider if they continue or are bothersome):

-constipation
-decreased hearing, ringing in the ears
-diarrhea
-headache
-nausea
-passing gas
-stomach pain
-upset stomach

This list may not describe all possible side effects for Mefenamic Acid. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.