Diltiazem is a medication primarily used to treat high blood pressure and certain heart conditions, such as angina and arrhythmias. It belongs to a class of drugs known as calcium channel blockers, which work by relaxing the blood vessels and improving blood flow, thereby reducing the heart's workload. This medication can be taken in various forms, including tablets and extended-release capsules. Common side effects may include dizziness, headache, and swelling in the legs or ankles. Patients should consult their healthcare provider for proper dosage and to discuss any potential interactions with other medications.