Diltiazem Side Effects

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

• Lightheadedness or dizziness
• Weakness
• Headache
• Flushing
• Slow heartbeat
• Diarrhea
• Constipation
• Vomiting
• Cough
• Nasal congestion

Some of the adverse effects of diltiazem are more serious. Call your doctor right away or seek emergency medical attention if you develop the following adverse effects:

• Serious skin reactions (rash, hives, swelling, peeling, blistering)
• Swelling of the face, eyes, lips, tongue, hands, arms, lower legs, ankles, or feet
• Trouble breathing or swallowing
• Fainting
• Nausea
• Loss of appetite
• Unusual tiredness
• Lack of energy
• Muscle pain
• Right upper abdominal pain
• Yellowing of the skin or eyes
• Dark urine
• Unusual bleeding or bruising
• Flu-like symptoms
• Worsening angina (chest pain) 

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

Diltiazem Overdose: In case of an overdose of diltiazem, call your doctor immediately. You can also call your local poison control center or the national poison control center at 1-800-222-1222. Overdose symptoms may include dizziness, confusion, a fast, slow, or irregular heartbeat, loss of consciousness (fainting), seizures, difficulty breathing, nausea, vomiting, and excessive sweating.

Source: FDA