Phenytoin Side Effects

Possible side effects of phenytoin are listed below. Call your doctor for medical advice if they are severe or persist after a few days.

• Headache
• Insomnia
• Abnormal movements in any part of the body
• Problems with coordination
• Uncontrolled eye movements
• Slurred speech
• Confusion
• Changes in taste 
• Constipation
• Facial coarsening
• Enlargement of the lips
• Unwanted hair growth
• Gum overgrowth
• Pain in the penis or curving of the penis

Phenytoin can also cause more serious side effects. Tell your doctor right away or seek emergency medical attention if you develop the following signs and symptoms:

• Swelling of the face, eyes, lips, mouth, or throat
• Shortness of breath
• Difficulty breathing or swallowing
• Skin rash, hives, itching, blisters
• Swollen glands anywhere in the body
• Unusual tiredness
• Nausea, vomiting, right upper stomach pain, yellowing of the skin or eyes
• Unusual bleeding or bruising
• Pinpoint red or purple spots in the skin
• Flu-like symptom (loss of appetite, fever, sore throat)
• Mouth ulcers
• Chest pain, dizziness, fatigue, irregular heartbeat

The above list may not include all the potential adverse effects of phenytoin. Contact your healthcare provider if your side effects are unusual or severe or do not get better over time. You can also report unusual side effects to the Food and Drug Administration at 1-800-FDA-1088.

Phenytoin Overdose: In case of an overdose of phenytoin, call your doctor immediately. You can also call your local poison control center, provincial poison control center, or the national poison control center at 1-800-222-1222. Call 911 or emergency services if a person has collapsed, cannot breathe, has had a seizure, or cannot be awakened. Symptoms of phenytoin toxicity may include uncontrolled shaking of any part of the body, uncontrolled eye movements, poor coordination, blurred vision, slurred speech, tiredness, dizziness, nausea, vomiting, loss of consciousness, chest pain, shortness of breath, and irregular heartbeat.

Source: FDA