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As is true for any other medication, there may be some instances where sildenafil use is not recommended or usage will have to be adjusted in order to prevent or reduce the risk of negative interactions occurring from other drugs, medical conditions, or even certain foods and drinks.

Drug Interactions

According to the U.S. National Library of Medicine, drugs that may interact with sildenafil include the following:

  • Nitrates (e.g., nitroglycerin) ,(nitroglycerin sublingual (Nitrostat), isosorbide mononitrate)
  • Tadalafil (Cialis, Adcirca)
  • Adderall
  • Antihypertensives (blood pressure lowering drugs) (e.g., amlodipine, lisinopril, losartan, valsartan)
  • Alpha blockers [e.g., terazosin (Hytrin), tamsulosin (Flomax)]
  • CYP3A4 inhibitors [e.g., ritonavir (Norvir)]
  • Guanylate cyclase (GC) stimulators [e.g., riociguat (Adempas)]

Please note that this list may not be complete, and other interactions with drugs not listed here may occur. Consult your physician or pharmacist before taking these medications with sildenafil.

Sildenafil and Nitrates

Nitrates are a class of drugs used to treat chest pain (angina) caused by heart disease. Nitrates include nitroglycerin, isosorbide dinitrate, isosorbide mononitrate, amyl nitrate, butyl nitrate, and street drugs known as nitrate “poppers.” 

Potential interactions between sildenafil and nitrates can be serious or even fatal. This may include a severe drop in blood pressure, which may lead to loss of consciousness, falls, shock, or even death. For this reason, it is contraindicated (not recommended) to take nitrates and sildenafil together.

Sildenafil and Tadalafil

Tadalafil (Cialis) is a similar drug and is also used to treat erectile dysfunction. It’s not proven that tadalafil and sildenafil negatively interact with each other, but that doesn’t mean it’s not possible. 

Sildenafil and Adderall

Adderall is a stimulant commonly prescribed to treat attention-deficit/hyperactivity disorder (ADHD). It’s not proven whether Adderall and sildenafil negatively interact with each other, but this fact doesn’t necessarily mean it’s not possible. If you take Adderall for ADHD and have trouble maintaining an erection or are experiencing low sex drive (libido), talk to your doctor about your options and whether sildenafil is right for you. 

Sildenafil and Nitric Oxide

Research shows that sildenafil can enhance the effects of inhaled nitric oxide (NO). NO is a gas that is used in a medical setting to help relax smooth muscles and widen blood vessels, meaning it works similarly as sildenafil. Cells in the human body also produce nitric oxide on their own, which is important for cardiovascular health. 

The interaction between medical NO gas and sildenafil may lead to negative consequences, including a drop in blood pressure and difficulty breathing. So, it is not recommended for these drugs to be taken together.

Food Interactions

Sometimes the foods we eat and the beverages we drink can also interact with our medications.

Food and drink that may interact with sildenafil include:

  • Alcohol
  • Grapefruit and grapefruit juice
  • Caffeine

Please note that this list may not be complete, and there may be other foods and beverages that interact with this drug.

Sildenafil and Alcohol

For more information, please visit our page on sildenafil and alcohol interactions.

Sildenafil and Grapefruit

Grapefruit is known to potentially interact with many medications, including sildenafil. Consuming grapefruit and grapefruit juice may increase the amount of sildenafil in the body, make it take longer for sildenafil to work, and ultimately affect the way the medication is metabolized. So, you should avoid consuming grapefruit while taking this drug. 

Sildenafil and Caffeine

Caffeine is a stimulant that increases blood flow. There are no known interactions between caffeine and sildenafil, but that doesn’t mean there aren’t any, and minor interactions are possible. Individuals taking sildenafil should check with their doctors before ingesting beverages and foods containing caffeine, including chocolate, energy drinks, and coffee. 

Disease & Conditions Interactions

Sometimes, certain medications can increase the risk of negative side effects for patients with some diseases or other medical conditions. According to the U.S. National Library of Medicine, diseases and medical conditions that are known to negatively interact with sildenafil include:

  • Heart disease, heart failure [e.g., high blood pressure (hypertension), heart failure (congestive heart failure), cardiomyopathy (heart muscle disease)]
  • Blood disorders [e.g., sickle cell anemia (sickle cell disease), multiple myeloma (Kahler’s disease)]
  • Liver or kidney problems
  • Abnormalities with the penis (such as fibrous tissue formation in the penis or a bent penis with erection)

Please note that this list may not be complete, and there may be other diseases and medical conditions where patients should not take sildenafil.

Sildenafil and Blood Pressure

Clinical trials suggest that sildenafil may have only a mild lowering effect on a person’s blood pressure, whether or not they have high blood pressure (hypertension). However, it’s well known that sildenafil can negatively (and, indeed, dangerously) interact with other medications used to manage and treat high blood pressure (hypertension).

For this reason, anyone who has problems with their blood pressure (e.g., poorly controlled, too high, too low) should check with their doctor before taking sildenafil. 

Sildenafil and Diabetes

Research has shown that sildenafil may be a safe and effective treatment for individuals with diabetes who also have erectile dysfunction. But because diabetes is considered a major risk factor for heart disease and is often treated with medications like metformin which may interact with sildenafil, it’s important for anyone with diabetes to check with their doctors before taking it.

Sildenafil and Pregnancy

For more information, please visit our page on sildenafil and pregnancy risks.

Disclaimer: this article does not constitute or replace medical advice. If you have an emergency or a serious medical question, please contact a medical professional or call 911 immediately. To see our full medical disclaimer, visit our Terms of Use page.


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