Viagra and blood thinners are widely used by men,Many men who have a anticoagulant swallowing – for example after a heart attack, angioplasty or atrial fibrillation – notice that the blood flow in their penis has deteriorated. A PDE-5 inhibitor such as Viagra® can then provide a solution. However, you do not want to unnecessarily increase the risk of bruising, nosebleeds or internal bleeding.
Which medications are classified as “blood thinners”?
| Group | Examples | Operation in brief |
|---|---|---|
| Antiplatelets (anticoagulants) | acetylsalicylic acid (Ascal, Aspirin), clopidogrel, prasugrel, ticagrelor | Make platelets less “sticky” → less chance of clot in stent or coronary artery |
| Vitamin K antagonists | acenocoumarol, fenprocoumon | Inhibit formation of clotting factors → INR value checked |
| Direct oral anticoagulants (DOACs) | rivaroxaban, apixaban, dabigatran, edoxaban | Inhibit thrombin or factor Xa → fixed dosage, no INR checks required |
| Heparins (injections/pumps) | LMWH (enoxaparin), unfractured. heparin | Rapid, temporary anticoagulation – often around operations |
Pharmacological: Does Viagra Affect Clotting?
- No, sildenafil does not affect platelets or clotting factors.
- The vasodilation can existing make minor bleeding (nose, gums, grazes) bleed a little faster.
- In clinical studies, no systematically higher risk of bleeding demonstrated in men concomitantly using anticoagulants and sildenafil.
Bottom line: there is no direct contraindication, but there are situations requiring extra caution.
When should you pay attention?
| Situation | Any action |
|---|---|
| INR > 3.5 (when using coumarin) | Wait until INR is stable (< 3.0) or consult thrombosis service/doctor. |
| Dual antiplatelet therapy (DAPT) – e.g. aspirin + ticagrelor | Start with half dose (25–50 mg) sildenafil; assess nosebleeds/hematoma. |
| Recent gastrointestinal bleeding or ulcer | First heal the stomach; take extra antacid; consult a doctor. |
| Perioperative period | No sildenafil on the day of surgery: surgical wound does not like vasodilation. |
| Concomitant alcohol intake | Alcohol dilates blood vessels and can further lower blood pressure → increased risk of dizziness and post-bleeding. |
How often do side effects occur with the combination?
| Side effect | Only blood thinner | Blood thinner + sildenafil | Explanation |
|---|---|---|---|
| Spontaneous nosebleed | 3–8 %/year | ± 5–10 %/year | Increase limited; usually self-limiting |
| Bruise after a bump | 1 in 5 | 1 in 4 | Sometimes slightly larger due to vasodilation |
| Severe internal bleeding | 1–2 %/year (anticoag.) | ≈ 1–2 %/year | Large studies show no additional increase |
(Based on post-marketing surveillance and cardiology cohorts)
Practical tips for safe joint use
- Start low – 25 mg sildenafil is often already effective for mild ED; if necessary, you can increase to 50 mg.
- Take on an empty stomach (at least 2 hours after a high-fat meal) → lower peak blood pressure drop, less dizziness.
- Hydrate – 250 ml of water before and after reduces flushing and headache without affecting the clotting profile.
- Check blood pressure – especially if you are also taking a beta blocker or alpha blocker.
- Do not use NSAIDs (ibuprofen, naproxen) as a painkiller on the same day; choose paracetamol to avoid additional risk of bleeding.
- Beware of alcohol – keep it to a maximum of 1–2 units.
- Warning signals – persistent nosebleed > 20 min, black tar stools, sudden blurred vision → seek immediate medical attention.
Special links: nitrates, poppers and riociguat
A random memory: nitrates (nitroglycerin spray, isosorbide dinitrate) and “poppers” (amyl nitrite) you should never combine with sildenafil – blood pressure can drop to a life-threatening level. This is independent of blood thinners but of course becomes more critical in people who already have cardiovascular problems.
Also the pulmonary hypertension drug riociguat is prohibited together with Viagra.
Frequently Asked Questions About Viagra and Blood Thinners
Does sildenafil change my INR?
No, there is no interaction via liver enzymes or vitamin K cycle. INR values remain stable.
2. Can I combine DOAC + 50 mg sildenafil and 100 mg aspirin?
Possible if your doctor has already prescribed this regimen (e.g. after TAVI), but monitor for easy bruising and consider half sildenafil dose.
3. Can I stop taking a blood thinner to take Viagra?
No - never stop anticoagulation on your own initiative. The risk of thrombosis is usually greater than any potential benefit.
In short
Viagra and blood thinners go together in most cases: sildenafil does not directly affect clotting. Stick to a low starting dose, good hydration and stay alert for nosebleeds or bruising. Always discuss use with your GP, cardiologist or thrombosis service, especially if you have a high INR, use dual platelet inhibition or have recently had a bleed. Safe fun starts with a good conversation - and with common sense in the amount of alcohol and medicines you combine.
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