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Unsafe Interactions With Sildenafil (Viagra)

UPGUYS > Blog > ED Treatment > Unsafe Interactions with Sildenafil (Viagra)
The person who wrote this article

Published on May 19, 2023

Disclaimer: Your healthcare provider is the best source of health and medical information. Articles written by UPGUYS are informed by peer-reviewed studies and research, as well as governmental health authorities and agencies—but they cannot replace advice from a healthcare professional. Talk to your healthcare provider about any physical or mental health concerns you might have. 

Recreational use of erectile dysfunction medications like Viagra (sildenafil), Cialis (tadalafil), and Levitra (vardenafil) is unsafe for a lot of reasons. Whereas consulting with a medical professional will allow the doctor to go over your medical history, tell you about all the possible side effects, and decide whether or not ED medication is right for you, recreational use puts your health at risk—there is even some evidence that young men who take ED meds recreationally might actually increase their chances of developing ED

Although you can always buy Viagra from Canada, your doctor can make you aware of this pill's side effects and the potential for drug interactions that exist between sildenafil and other medications. Viagra has been known to interact with dozens of different prescription and non-prescription medications—sometimes, the interactions can be severe. 

Although a visit with a doctor is the best way to know which drugs can potentially interact with Viagra, Cialis, and Levitra, here is a list of the most common medications that have been known to interact with erectile dysfunction medication. 

Alpha Blockers

Also known as a-blockers or α-adrenoreceptor antagonists, alpha blockers are drugs generally used in combination with other drugs to treat hypertension and prostate problems in men. A few of the more common Alpha Blockers on the market are: Uroxatral (alfuzosin), Cardura (doxazosin), Minipress (prazosin), Flomax, in Jalyn (tamsulosin), and terazosin.

Beta Blockers

By causing the heart to beat more slowly and with less force, Beta Blockers are often used to lower blood pressure in patients. They can also help open arteries and veins in the body to help improve blood flow. Beta Blockers also treat heart conditions like abnormal heart beat, and are sometimes used to help patients recover from a heart attack. Some Beta Blockers to look out for include Acebutolol (Sectral), Atenolol (Tenormin), Bisoprolol (Zebeta), Metoprolol (Lopressor, Toprol XL), Nadolol (Corgard), Nebivolol (Bystolic), Propranolol (Inderal, InnoPran XL). 

Antifungal Medication

While not all antifungal medications have been shown to interact with Viagra, there are few to avoid. Drugs like Onmel and Sporanox, whose active ingredient is itraconazole, are used to fight bacterial infections in the mouth and throat, as well as toenails. Nizoral (ketoconazole), used to treat skin conditions like athlete’s foot, ringworm and dandruff, should also be avoided. 

HIV Protease Inhibitors

These drugs are used to reduce the proliferation of HIV in infected patients by stopping new HIV cells from maturing. HIV Protease Inhibitors that can interact with ED meds include Reyataz, in Evotaz (atazanavir), Prezista, in Prezcobix (darunavir), Lexiva (fosamprenavir), Crixivan (indinavir), in Kaletra (lopinavir), Viracept (nelfinavir), Norvir, in Kaletra (ritonavir), Invirase (saquinavir), and Aptivus (tipranavir). 

Anti-Seizure Medication 

Seizure medication including Carbatrol, Epitol, Tegretol, others (carbamazepine), phenobarbital, and Dilantin, Phenytek (phenytoin) can all interact dangerously with Viagra. 


Barbiturates have been used for more than a century to treat serious conditions like schizophrenia and epilepsy, thanks to their ability to sedate and relax patients. But, like all other drugs on this list, they can interact with sildenafil and cause detrimental effects. Tell your doctor if you take certain barbiturates like in Butapap, in Fioricet, in Fiorinal, others (butalbital) and Seconal (secobarbital). 

Other Erectile Dysfunction Medications

Erectile dysfunction meds like Viagra, Cialis and Levitra and not meant to be mixed and matched. If you’ve already been prescribed one of these ED medications and want to try another one, make sure you make a complete switch and talk to your doctor before changing approaches. 

Other Medications That Can Interact Dangerously with Viagra

  1. Norvasc, in Amturnide, in Tekamlo (amlodipine)
  2. Blood thinners, such as Coumadin, Jantoven (warfarin)
  3. Tracleer (bosentan)
  4. Cimetidine
  5. Sustiva, in Atripla (efavirenz)
  6. E.E.S., E-Mycin, Erythrocin (erythromycin)
  7. Medications for high blood pressure
  8. Mycobutin (rifabutin)
  9. Rifadin, Rimactane, in Rifamate, in Rifater (rifampin)
  10. St. John’s wort

Talk To Your Doctor

Don’t risk serious medical complications by taking Viagra without a prescription. Make an appointment with a doctor and be ready to talk about any medications you’re currently taking, as well as your medical history. You’ll be happy you did.

This article is written for informational purposes only and does not constitute medical advice. The information provided in the articles cannot and should not replace advice from a healthcare professional. Talk to your healthcare provider about any physical or mental health concerns or the risks and benefits of any treatment or medication.