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Is Viagra a Blood Thinner?

Katelyn Hagerty

Medically reviewed by Katelyn Hagerty, FNP

Written by Our Editorial Team

Last updated 9/19/2021

Viagra®, which contains the active ingredient sildenafil, is one of the most popular medications on the market for treating erectile dysfunction (ED).

Like other medications for ED, Viagra works by increasing blood flow to your penis. This makes it easier to get and sustain an erection, especially with sexual stimulation. 

If you’ve researched using Viagra to treat ED for sexual intercourse, you may have read that it can have certain effects on your circulatory system, especially when it’s used in combination with other medications.

Currently, there’s no research that suggests that Viagra is a blood thinner. However, there are a few things that you should know if you’re thinking of using Viagra with medications that thin your blood or have other effects on your cardiovascular system. 

We’ve explained these below, along with more information on how Viagra works as a treatment for ED, its effects on your blood and more. 

How Does Viagra Work?

Viagra belongs to a class of medications called phosphodiesterase type 5 (PDE5) inhibitors. 

It works by promoting the relaxation of blood vessels located throughout your body, including the blood vessels that control the flow of blood to your penis.

Erections are all about strong blood flow. When you’re sexually aroused, blood flows into tissue inside your penis called the corpora cavernosa. 

As pressure builds, your penis becomes firmer and larger, creating an erection that’s strong enough for sex.

Contrary to popular belief, Viagra doesn’t have any effect on sexual arousal. All it does is make it easier to get an erection when you already feel sexually aroused and stimulated.

Interestingly, Viagra wasn’t originally developed as a medication for ED. In the early stages of its development, Pfizer’s team of scientists instead thought of sildenafil as a potential treatment for cardiovascular health issues such as angina (a type of chest pain caused by poor blood flow).

During sildenafil trials in the early 1990s, many patients who were given the medication as an experimental treatment for angina reported erections as a side effect.

As a result of this, Pfizer adjusted its focus and began testing sildenafil as a treatment option for erectile dysfunction, resulting in the Viagra we’re familiar with today. 

Although the brand name medication Viagra is used exclusively to treat ED, sildenafil (the active ingredient in the medication) is also prescribed to treat pulmonary arterial hypertension (PAH), a form of high blood pressure that affects arteries inside the lungs.

This is because sildenafil improves blood flow in all blood vessels that contain PDE5, including those in parts of the body other than the penis. 

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What Are Blood Thinners?

Blood thinners are medications that reduce your risk of developing blood clots, and can stop existing blood clots from growing in size.

Your healthcare provider may prescribe a blood thinner if you’ve been diagnosed with a heart or blood vessel disease, if you have a congenital heart defect, if you’ve recently undergone certain types of surgery or if you have atrial fibrillation, a common type of heart arrhythmia.

Blood clots can prevent blood from flowing properly throughout your body and potentially cause you to experience a heart attack, stroke or other medical emergency. 

Two main types of blood thinners are in use today: anticoagulants and antiplatelets. 

Anticoagulants work by slowing the process through which blood clots form. 

Common anticoagulants include warfarin (sold as Coumadin® and Jantoven®), enoxaparin (Lovenox®) and the injectable medication, heparin.

Antiplatelet medications work by preventing small blood cells called platelets from forming into clots. 

Common antiplatelets include clopidogrel (Plavix®), ticlopidine (Ticlid®), dipyridamole (Persantine®) and aspirin.

If you’re prescribed a blood thinner, it’s important to use it as directed. Make sure to talk to your healthcare provider before using blood thinners with other medications.

Does Viagra Have Blood Thinning Effects?

Thanks to Viagra’s early history as a cardiovascular medication and its use in treating conditions related to blood flow, many people assume that it works by thinning your blood. 

Currently, there’s no scientific evidence to suggest that sildenafil is an effective anticoagulant, or blood thinner. 

There’s also no research showing that sildenafil has significant antiplatelet effects (meaning it works to prevent platelets from clumping together and forming a blood clot). 

In simple terms, brand name Viagra and generic sildenafil don’t appear to have any major blood thinning effects. 

That said, because of its effects on blood vessel dilation, Viagra does have a mild effect on blood pressure. 

In a 2002 study published in Urology, researchers measured a drop of 5.3 mm Hg in mean arterial pressure in men who used sildenafil at a 100mg dose (the strongest dose used for erectile dysfunction).

Is It Safe to Use Viagra with Blood Thinners?

Sildenafil, the active ingredient in Viagra, can interact with some medications used to treat heart health issues, including several medications for hypertension (high blood pressure). 

However, there are currently no known significant interactions between sildenafil or other drugs used to treat ED and common blood thinners. 

Despite this, if you’re prescribed a blood thinner, it’s important to talk to your healthcare provider before using Viagra, generic sildenafil or any other medications to treat ED.

It’s especially important to take caution if you’re prescribed a blood thinner due to a heart health issue, such as cardiovascular disease or a congenital heart defect.

Although Viagra itself isn’t harmful to your cardiovascular health, sexual activity can put a strain on your heart. 

Make sure to talk to your doctor about the safety of engaging in sexual activity if you have heart disease, have suffered a heart attack or have other heart health issues.

Viagra Side Effects, Interactions and Safety

Overall, Viagra is a safe and effective medication for most men. In large-scale studies, upwards of 95 percent of men who use Viagra for ED report being satisfied with its effects on their sexual performance and erectile function.

Like other medications, Viagra can cause potential side effects. The most common side effects of Viagra include:

  • Headache

  • Dyspepsia (indigestion)

  • Flushing

  • Back pain

  • Myalgia (muscle aches and pain)

  • Abnormal vision

  • Nasal congestion

  • Nausea

  • Dizziness

  • Rash

You may have a higher risk of experiencing side effects if you’re prescribed Viagra at a relatively high dose, such as 100mg as needed.

Although uncommon, Viagra may cause more severe side effects. It’s important to contact your healthcare provider if you develop severe, persistent or worrying side effects after using Viagra or any other medication to treat ED. 

If you experience dizziness or shortness of breath, seek emergency medical assistance. 

Viagra and other ED medications can interact with other medications, including several common medications used to treat high blood pressure.

You should not take Viagra or other ED medications if you’re prescribed nitrates. Used together, these medications can trigger a sudden decrease in blood pressure that may cause you to feel dizzy, faint or experience a heart attack or stroke.

To keep yourself safe, make sure to let your healthcare provider know about all medications you currently use or have recently used before using Viagra. 

Other Medications for Treating ED

In addition to Viagra, several other medications are available to treat erectile dysfunction. These medications also work by inhibiting PDE5 and increasing blood flow to the erectile tissue of your penis. Options include:

  • Tadalafil. Sold under the brand name Cialis®, this is a long-lasting ED medication that can provide relief for 24 to 36 hours per dose.



  • Vardenafil. Sold under the brand name Levitra®, this medication provides relief from ED for four to five hours per dose.



  • Avanafil. Available as Stendra®, this is a second-generation ED medication that works in as little as 15 minutes and has a reduced risk of causing certain side effects. 

Check out this guide on the most common erectile dysfunction treatments for more information about how these medications work, as well as how they differ from Viagra. 

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Is Viagra Best for You?

Viagra is a popular erectile dysfunction drug that’s been in use since the late 1990s. It’s helped millions of men more easily experience sexual intercourse.

And although it was originally developed as a treatment for angina, there isn’t any scientific evidence to suggest that Viagra has blood thinning effects. 

If you have heart disease and/or you’re prescribed a blood thinner and want to take Viagra or other medication for ED, it’s best to talk to your healthcare provider ahead of time. They’ll be able to let you know about how you can treat ED safely.

Want to get started with Viagra? Find a full range of ED medications and access treatment following an online consultation with a licensed healthcare provider. 

9 Sources

Hims & Hers has strict sourcing guidelines to ensure our content is accurate and current. We rely on peer-reviewed studies, academic research institutions, and medical associations. We strive to use primary sources and refrain from using tertiary references.

  1. Smith, B.P. & Babos, M. (2021, June 29). Sildenafil. StatPearls. Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK558978/
  2. Dhaliwal, A. & Gupta, M. (2021, June 25). PDE5 Inhibitors. StatPearls. Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK549843/
  3. Erection Ejaculation: How It Occurs. (2020, November 27). Retrieved from https://my.clevelandclinic.org/health/articles/10036-erection-ejaculation-how-it-occurs
  4. Ghofrani, H.A., Osterloh, I.H. & Grimminger, F. (2006). Sildenafil: from angina to erectile dysfunction to pulmonary hypertension and beyond. Nature Reviews Drug Discovery. 5 (8), 689–702. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7097805/
  5. Smith, B.P. & Babos, M. (2021, June 29). Sildenafil. StatPearls. Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK558978/
  6. Blood Thinners. (2021, July 8). Retrieved from https://medlineplus.gov/bloodthinners.html
  7. Vardi, Y., Klein, L., Nassar, S., Sprecher, E. & Gruenwald, I. (2002, May). Effects of sildenafil citrate (viagra) on blood pressure in normotensive and hypertensive men. Urology. 59 (5), 747-52. Retrieved from https://pubmed.ncbi.nlm.nih.gov/11992853/
  8. VIAGRA® (sildenafil citrate) tablets, for oral use. (2014, March). Retrieved from https://www.accessdata.fda.gov/drugsatfda_docs/label/2014/20895s039s042lbl.pdf
  9. Carson, C.C., Burnett, A.L., Levine, L.A. & Nehra, A. (2002, September). The efficacy of sildenafil citrate (Viagra) in clinical populations: an update. Urology. 60 (2 Suppl 2), 12-27. Retrieved from https://pubmed.ncbi.nlm.nih.gov/12414330/

This article is for informational purposes only and does not constitute medical advice. The information contained herein is not a substitute for and should never be relied upon for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.

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