Phosphodiesterase-5 inhibitors, such as Kamagra / Viagra, Levitra, or Apcalis / Cialis, have revolutionized the treatment of erection problems (erectile dysfunction). However, they can cause life-threatening side effects for anyone who also takes nitroglycerin or another medication containing an organic nitrate. This combination can make your blood pressure fall too low, possibly leading to a stroke, a heart attack, or death.

Medications that contain organic nitrates include:

• Nitroglycerin (such as Deponit, Minitran, Nitrek, Nitrodisc, Nitro-Dur, Nitroglyn, Nitrolingual Spray, Nitrostat).
• Isosorbide mononitrate (such as Imdur, ISMO, Monoket Tablets).
• Isosorbide dinitrate (such as Dilatrate-SR, Isordil, Sorbitrate).
• Pentaerythritol tetranitrate (such as Duotrate, Peritrate, Tetraneed).
• Sodium nitroprusside (such as Nipride, Nitropress).
• Amyl nitrite (sometimes called "poppers"), which are sometimes abused.

Nitrate drugs are used to treat the symptoms of angina which have to do with heart issues and chest pain. Nitrate drugs relieve an attack that is occurring, this is what is referred to as “Nitro”, to prevent attacks from occurring by using the medicine just before an attack is expected to occur, such as when strenuous activity has taken place and a person has a particular history of heart problems or in reducing the number of attacks that occur by using the medicine regularly on a long-term basis. Using the medicine on a long term basis is not advisable is it can be avoided. 

Nitrate drugs can be taken orally and swallowed. Taking the medicine in this fashion, Nitrates are used to reduce the number of angina attacks that a person has. When Nitrates are in this form, the kind to be swallowed, they are not strong enough to prevent a heart episode if it occurs. Nitrate drugs work by relaxing blood vessels and increasing the supply of blood and oxygen to the heart while reducing its work load. The drug forces the blood vessels to relax thus helping the blood flow more freely. When Nitrates are taken to stop a heart attack or an attack of angina they are in a much stronger dose. The blood vessels are opened more rapidly which is why most patients complain of an immediate headache after having it administered. 

Nitrate drugs are also some times used for other conditions but that is for a doctor to decide. Nitrates are only available with a prescription and the drug is strongly controlled. 

As with any medicine Nitrates have reactions to other drugs and conditions and you should be honest with your doctor about any pre-existing conditions or drugs that you may already be taking. Some of the things to consider if you are considering taking nitrate drugs are things such as allergies and if you have ever had any unusual or allergic reaction to nitrates or nitrites. Your doctor will also need to know if you are allergic to any other substances, such as certain foods, preservatives, or dyes. Certain allergies could effect the way the drugs work or can cause an adverse reaction.

Nitrates found in foods are not a danger when taking phosphodiesterase-5 inhibitors.