Diltiazem Side Effects, Upsides, Downsides & Tips

Diltiazem is from a group of medicines called calcium channel blockers which work by relaxing the muscles in the blood vessels and heart.


It is primarily used for treating angina, certain heart rhythm disorders, and hypertension. It also helps you exercise for a longer period and lowers heart rate. Diltiazem makes blood flow easier, and the heart has to put in less effort to pump blood.



Side effects

Common side effects of Diltiazem include:

  • A headache
  • Constipation
  • Dizziness
  • Lightheadedness
  • Nausea
  • Weakness
  • Flushing


Serious side effects of Diltiazem include:

  • Worsening or new symptoms of heart failure
  • Fainting
  • Unusual tiredness
  • Irregular heartbeat
  • Mental or mood changes
  • Yellowing eyes and skin
  • Persistent nausea
  • Unusual dreams
  • Severe abdominal pain
  • Dark urine


Experiencing a serious allergic reaction to Diltiazem is quite rare. On noticing the following symptoms, get instant medical help.

  • Rash
  • Trouble breathing
  • Severe dizziness
  • Itching or swelling


How to take diltiazem

Diltiazem is to be taken orally before meals as well as at bedtime 3 to 4 times a day. Your doctor will instruct you better regarding the dosage.

Since Diltiazem is an extended-release tablet, it must not be opened, crushed, chewed, or broken. Instead, it has to be swallowed whole. However, if you face difficulty in swallowing it whole then ask the doctor if you can open up the capsule and sprinkle the powder inside on a spoon filled with applesauce. Swallow this mixture without chewing and don’t save it for use later.

Use it regularly if you want to get the most benefits. Make sure you get a refill before you completely run out of medicine.


Do not stop the use of Diltiazem suddenly. Make sure you stop it gradually as ceasing the use of this medicine all of a sudden can worsen your condition.

If you are using Diltiazem for treating high blood pressure, then you must continue using it even if you feel good. High blood pressure, in most cases, has no symptoms so you might need to use the medicine for a long time.

During your treatment with Diltiazem, your blood pressure will have to be, and you may also be asked to take blood tests frequently.



Avoid Diltiazem if you are allergic to it. Do not use Diltiazem if you have the following:

  • A recent heart attack resulting in the build-up of fluid in the lungs
  • Extremely low blood pressure
  • A serious heart problem such as an AC block or sick sinus syndrome
  • To ensure Diltiazem doesn’t put your health at risk, inform the doctor of the following:
  • If you take digoxin or a beta blocker like sotalol, metoprolol, atenolol, carvedilol, etc.

It is still unclear whether Diltiazem can harm an unborn baby; thus, it is better to inform your doctor if you are planning a baby or are pregnant. Similarly, diltiazem can pass into the breast milk and harm the nursing infant. Therefore, avoid breastfeeding when using this medicine. Instead, ask your doctor to prescribe you an alternative.

As with all medicines, make sure to consult a doctor before you start your treatment with diltiazem.