Nitrates

Nitrates release nitric oxide, which relaxes veins and arteries and reduces how hard the heart has to work. Nitroglycerin relieves and prevents angina and is used in heart attacks and heart failure. Headache and low blood pressure are common, so doses are taken sitting down. They must never be combined with PDE5 inhibitors such as sildenafil, because blood pressure can drop dangerously.

• NitroglycerinKnown brand names include Nitrostat.