Isosorbide Mononitrate – What It Is and Why You Might Need It

If you’ve been told you have stable angina, chances are your doctor mentioned a nitrate called isosorbide mononitrate. It’s a long‑acting pill that helps keep chest pain at bay by relaxing the blood vessels around the heart.

How It Works

The drug releases nitric oxide, a natural chemical that tells the smooth muscle in your arteries to loosen up. When those vessels widen, your heart doesn’t have to work as hard to push blood through, and the pain that comes from reduced oxygen drops away.

Because it’s designed to last 24 hours, you usually take one dose once a day. That steadier level in your bloodstream means fewer “breakthrough” episodes compared with short‑acting nitrates that need several doses throughout the day.

Using Isosorbide Mononitrate Safely

Start by following the exact amount your doctor wrote on the prescription. Typical doses are 10 mg, 20 mg, or 40 mg taken in the morning with water. Swallow the tablet whole; crushing or chewing can release too much nitrate at once and cause a sudden drop in blood pressure.

Give yourself a few days to notice how you feel. If you get a headache, that’s common – it means the vessels are widening as intended. Over‑the‑counter pain relievers like acetaminophen usually help. If headaches become severe or you feel dizzy when standing up, call your doctor.

Watch out for interactions. Medications such as sildenafil (Viagra) or other drugs for erectile dysfunction can cause a dangerous blood pressure plunge when combined with nitrates. Always list every medicine, supplement, and even herbal product you’re taking.

Avoid alcohol in excess while on this drug. Alcohol also widens blood vessels, which can add to the blood‑pressure‑lowering effect and make you feel faint.

Pregnancy and breastfeeding? Tell your health provider right away. The safety data are limited, so a different angina treatment may be recommended.

If you miss a dose, take it as soon as you remember – unless it’s almost time for the next one. In that case, skip the missed pill; double‑dosing can increase side‑effect risk.

Store the medication at room temperature, away from heat and moisture. Keep it out of reach of children – even a tiny amount can be harmful.

Finally, keep an eye on your symptoms. If chest pain returns or worsens despite taking isosorbide mononitrate, don’t wait. Seek medical help right away; you may need an adjustment in dose or a different therapy.