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Enjoy sex like you used to
Reviewed by Kelly Brown MD, MBA
Written by Geoffrey C. Whittaker
Published 09/18/2021
Updated 07/16/2024
Often called “the little blue pill,” Viagra® is commonly prescribed first-line erectile dysfunction (ED) medication for men. The brand-name medication and its generic version, sildenafil, have been helping millions of men get — and stay — erect during sex since it was approved in 1998 by the U.S. Food and Drug Administration (FDA).
So, what is this medication exactly?
And is Viagra a blood thinner?
While both types of medications help treat pulmonary arterial hypertension, Viagra and blood thinners are not the same thing — and taking them together or as substitutions for one another could be seriously dangerous.
Here’s what you need to know.
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Blood thinners are medications used to prevent the formation or worsening of blood clots. A blood clot is a mass of blood cells and other substances in your blood that form within your blood vessels.
When you get a cut on your skin or have a damaged vein or artery, blood cells eventually clump together to form a blood clot and help control the bleeding. This is a natural part of healing, but it can become a problem if a blood clot fails to break down properly when its job is done.
Blood clots can be dangerous if they detach from your veins or arteries and travel through your body. When this happens, the clot might end up in your heart or brain and cause a heart attack or stroke. They could also land in your kidneys, lungs, or limbs and cause damage to your organs.
Ultimately, blood clots are serious. If they’re not prevented or treated properly, they can be fatal.
Therefore, someone who has a higher risk for a stroke or heart attack may be prescribed a blood thinner. This includes those who have risk factors, like an irregular heart rhythm (arrhythmia) or heart or blood vessel disease, as well as people who previously had a heart attack or stroke.
Blood thinners prevent blood clots from forming and help blood flow more smoothly throughout the body. The two main types are:
Anticoagulants, which slow the formation of blood clots. Common anticoagulants include Coumadin® and Jantoven® (warfarin), Lovenox® (enoxaparin), and the injectable medication heparin.
Antiplatelets, which prevent small blood cells called platelets from forming clots. Common antiplatelets include Plavix® (clopidogrel), Ticlid® (ticlopidine), Persantine® (dipyridamole), and aspirin.
Which medication is right for you depends on your condition and health history. A healthcare provider will ultimately determine the best type of blood thinner for your situation.
Viagra is not considered a blood thinner, and neither are otherphosphodiesterase type 5 inhibitors, such as Stendra®(avanafil), Levitra (vardenafil), or Cialis® (tadalafil).
Viagra is a PDE5 inhibitor, a category of drugs considered the gold standard in ED treatment. PDE5 inhibitors help with erectile function by way of their vasodilatory effects — they help widen the blood vessels and relax vascular smooth muscle, allowing blood to flow to the penis more easily. They do this by blocking an enzyme called PDE5 from doing its job, which is to decrease blood flow to the penis and soften an erection.
Viagra and other PDE5 inhibitors are not known to have significant blood-thinning effects, but they can lower blood pressure.
Because of Viagra’s vasodilatory effects on the cardiovascular system, it can potentially cause a dangerous drop in blood pressure.
For example, in a 2002 study conducted over two nights, 49 men with either normal or high blood pressure were given no medication the first night and 100mg of sildenafil the following night.
The authors monitored participants' blood pressure and heart rate and noted differences between the two nights. They found that sildenafil resulted in a clinically insignificant reduction in blood pressure among all men in the study.
According to the Viagra label, higher doses are more likely to cause reduced blood pressure for some users. However, it also says the drop usually isn’t significant enough to cause noticeable symptoms.
Still, it’s crucial to tell your healthcare provider your complete medical history and any other medications you’re taking before using it.
Interestingly, the discovery of PDE5 inhibitors for erectile dysfunction treatment was accidental.
Researchers were studying how PDE5 inhibitors could treat heart problems like hypertension (high blood pressure) and related chest pain. When the participants started experiencing surprise erections as a side effect, let’s just say the research took a turn.
The fact that the initial intended use of Viagra was for cardiovascular health might be one reason many people are under the impression that it acts as a blood thinner.
Sildenafil is now a gold standard drug for ED, but it still has some off-label uses — which means they’re prescribed for a different purpose than what the FDA approved them for — related to circulation. Specifically, sildenafil is used off-label for secondary Raynaud phenomenon, female sexual arousal disorder, and as an adjunct in the treatment of altitude-induced hypoxemia.
While sildenafil sold under the brand name Viagra is only FDA-approved for erectile dysfunction, sildenafil sold under the brand name Revatio® is FDA-approved for pulmonary hypertension. This is a serious condition involving high blood pressure in the vessels of the lungs.
ED medications can increase your risk of serious cardiovascular issues when taken without proper medical advice. So, while you can take Viagra and blood thinners together, you should not do so without a healthcare professional’s instruction — and we have to stress that you shouldn’t take either type of medication without a prescription.
Erectile dysfunction and health conditions that warrant the use of blood thinners are both very common. This means many men who use ED drugs may also be prescribed anticoagulants.
Before you start using these two types of medication together, make sure your healthcare provider is aware you’re already taking one or the other, as taking Viagra with anticoagulants may increase your risk of bleeding.
It’s worth noting that there have been reports of bleeding among some men who just take Viagra, but a causal relationship between the two hasn’t been established.
Still, it’s best to proceed with caution, especially 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.
Don’t be afraid to express any concerns before taking one or both of these medications — that’s what your provider is there for.
You might also be wondering, do blood thinners cause ED? Since ED is a multifactorial condition, this is a valid question.
While some cardiovascular conditions can increase your risk of developing ED, there’s no solid evidence that blood thinners themselves cause it. However, there’s a strong correlation between ED and having high blood pressure and high cholesterol, both of which could be reasons you’re prescribed a blood thinner.
Before starting a new medication, your first step should be to learn about the potential side effects and interactions.
Some possible side effects of Viagra are a bit annoying but not necessarily a big deal. Others should be taken more seriously and warrant speaking with a medical professional immediately. In some cases, you may need to consider switching from Viagra to other treatment options.
The side effects of any drug are unpredictable. Not everyone using Viagra will experience adverse effects, and experiences can be vastly different between two people. Pay attention to anything that feels “off” when using Viagra.
Some of the more common (and typically temporary) side effects of Viagra include:
Headaches
Nasal congestion
Nausea
Heartburn
Blurred vision
Back pain
Facial flushing
Dizziness
Low blood pressure
Muscle aches
Nose bleeds
Trouble falling or staying asleep
These side effects generally occur while Viagra is active in your body, though some may continue briefly after the medication wears off.
Viagra might also result in less common but more serious side effects, like:
Priapism (an erection lasting more than four hours)
Sudden hearing loss
Vision loss due to damage to the optic nerve
Seek immediate medical attention if you experience any symptom that concerns you. Better safe than sorry, especially when it comes to your body.
All drugs come with a risk of interactions with both over-the-counter (OTC) or prescription drugs, as well as certain supplements. Some of the most important potential Viagra interactions to be aware of are medications used to treat cardiovascular conditions.
You shouldn't take sildenafil with nitrate medications like nitroglycerin or alpha-blockers. These drugs are prescribed to treat high blood pressure, congestive heart failure, or angina, which is chest pain relating to reduced blood flow to the heart.
When you take these drugs at the same time as Viagra, it can trigger a sudden drop in blood pressure. At best, this doesn’t feel good, and there’s a chance it can make you pass out.
The combination may even cause reduced blood flow or severe dilation of your blood vessels. In some cases, this can set you up for a heart attack.
Viagra also shouldn’t be taken with recreational drugs like “poppers.” These often contain substances like amyl nitrate that can interact similarly to the above prescription medication and cause severely low blood pressure.
Viagra may be less effective for men with certain health conditions. While discussing other medications you use, make sure your provider is also aware of any existing diagnoses you have.
For instance, sildenafil should be used cautiously by men who have:
Existing cardiovascular conditions that make them more susceptible or sensitive to changes in blood pressure
Bleeding disorders
Peptic ulcers
Physical deformation of the penis, like Peyronie’s disease, which causes curved, sometimes painful erections due to the formation of scar tissue
A higher risk for priapism (prolonged erection without stimulation)
When in doubt, always check in with your healthcare provider.
Everyday lifestyle habits, like your diet, also matter when taking Viagra. There are certain foods to avoid with Viagra if you want it to work to its full potential.
Eating a meal high in fat — think a cheesy, cream-based pasta dish or a juicy cheeseburger with fries — the day you want to use Viagra can make it less effective. Do yourself and your partner a favor on date night and maybe order the dinner salad instead.
Grapefruit juice can also interact with sildenafil, changing how your body metabolizes the drug. Whilef being metabolized in your digestive tract, more of the sildenafil travels into your bloodstream, making it more potent, also known as increased bioavailability. This can result in flushing, a headache or low blood pressure.
Finally, while alcohol and sex often go together, it’s best not to double fist when taking Viagra. Combining the two increases your risk of experiencing side effects like headaches and flushing, especially when consumed in excess.
There are a lot of questions when it comes to ED drugs and blood thinners. Like many men, you may have asked Google questions like “Is Cialis® a blood thinner?” Or maybe you’ve wanted to know, “Does Viagra thin your blood?” Many people also wonder if they should use Viagra to prevent getting ED from a clog in their arteries.
If you’re using Viagra and are concerned about its effects on blood flow, keep the following in mind:
It’s not a blood thinner. Viagra and the other PDE5 inhibitors aren’t blood thinners. While anticoagulants slow your body’s process of making clots, Viagra works by relaxing blood vessels in your penis and increasing blood flow to the area.
It may cause low blood pressure. Even though sildenafil isn’t a blood-thinning medication, it can trigger a drop in blood pressure. Some men may not notice this at all, while others might experience severe side effects. This is more likely to happen when Viagra is combined with other drugs, especially blood pressure medication or nitrates.
It’s crucial to use as directed. Not using Viagra as it’s been prescribed can create more problems than ED. If you have questions about how to take sildenafil, speak with your healthcare provider or pharmacist. Looking for another option? Consider ED hard mints, chewable erectile dysfunction medication that can be personalized to fit your needs.
If you’re exploring the idea of using erectile dysfunction treatments but haven’t tried anything yet, take the first step toward improving your sex life with our free ED quiz.
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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. Learn more about our editorial standards here.
Dr. Kelly Brown is a board certified Urologist and fellowship trained in Andrology. She is an accomplished men’s health expert with a robust background in healthcare innovation, clinical medicine, and academic research. Dr. Brown was previously Medical Director of a male fertility startup where she lead strategy and design of their digital health platform, an innovative education and telehealth model for delivering expert male fertility care.
She completed her undergraduate studies at University of North Carolina at Chapel Hill (go Heels!) with a Bachelor of Science in Radiologic Science and a Minor in Chemistry. She took a position at University of California Los Angeles as a radiologic technologist in the department of Interventional Cardiology, further solidifying her passion for medicine. She also pursued the unique opportunity to lead departmental design and operational development at the Ronald Reagan UCLA Medical Center, sparking her passion for the business of healthcare.
Dr. Brown then went on to obtain her doctorate in medicine from the prestigious Northwestern University - Feinberg School of Medicine and Masters in Business Administration from Northwestern University - Kellogg School of Management, with a concentration in Healthcare Management. During her surgical residency in Urology at University of California San Francisco, she utilized her research year to focus on innovations in telemedicine and then served as chief resident with significant contributions to clinical quality improvement. Dr. Brown then completed her Andrology Fellowship at Medical College of Wisconsin, furthering her expertise in male fertility, microsurgery, and sexual function.
Her dedication to caring for patients with compassion, understanding, as well as a unique ability to make guys instantly comfortable discussing anything from sex to sperm makes her a renowned clinician. In addition, her passion for innovation in healthcare combined with her business acumen makes her a formidable leader in the field of men’s health.
Dr. Brown is an avid adventurer; summiting Mount Kilimanjaro in Tanzania (twice!) and hiking the incredible Torres del Paine Trek in Patagonia, Chile. She deeply appreciates new challenges and diverse cultures on her travels. She lives in Denver with her husband, two children, and beloved Bernese Mountain Dog. You can find Dr. Brown on LinkedIn for more information.
Education & Training
Andrology Fellowship, Medical College of Wisconsin
Urology Residency, University of California San Francisco
M.D. Northwestern University Feinberg School of MedicineB.S. in Radiologic Science, Chemistry Minor, University of North Carolina at Chapel Hill
Published as Kelly Walker
Cowan, B, Walker, K., Rodgers, K., Agyemang, J. (2023). Hormonal Management Improves Semen Analysis Parameters in Men with Abnormal Concentration, Motility, and/or Morphology. Fertility and Sterility, Volume 118, Issue 5, e4. https://www.sciencedirect.com/journal/fertility-and-sterility/vol/120/issue/1/suppl/S
Walker, K., Gogoj, A., Honig, S., Sandlow, J. (2021). What’s New in Male Contraception? AUA Update Series, Volume 40. https://auau.auanet.org/content/update-series-2021-lesson-27-what%E2%80%99s-new-male-contraception
Walker, K., Shindel, A. (2019). AUA Erectile Dysfunction Guideline. AUA Update Series, Volume 38. https://auau.auanet.org/content/course-307
Walker, K., Ramstein, J., & Smith, J. (2019). Regret Regarding Fertility Preservation Decisions Among Male Cancer Patients. The Journal of Urology, 201(Supplement 4), e680-e681. https://www.auajournals.org/doi/10.1097/01.JU.0000556300.18991.8e
Walker, K., & Smith, J. (2019). Feasibility Study of Video Telehealth Clinic Visits in Urology. The Journal of Urology, 201(Supplement 4), e545-e545. https://www.auajournals.org/doi/10.1097/01.JU.0000556071.60611.37