Sildenafil and Vedolizumab: Can They Be Taken Together?

Sildenafil and Vedolizumab: Understanding the Interaction

Published: 18 October 2026

If you're prescribed vedolizumab for inflammatory bowel disease and considering sildenafil for erectile dysfunction, you may wonder whether sildenafil and vedolizumab can be taken together safely. The good news is that no major direct interaction between these two medicines is commonly reported in clinical practice. However, every medication you take—including vedolizumab—must be declared during your consultation so that a UK prescriber can review your full medical history and ensure sildenafil is suitable for you.

What is sildenafil and vedolizumab?

Sildenafil is a phosphodiesterase type 5 (PDE5) inhibitor licensed to treat erectile dysfunction (ED). It works by relaxing blood vessels in the penis, allowing increased blood flow when you are sexually aroused [3]. Sildenafil is the active ingredient in Viagra and is available in 25 mg, 50 mg, and 100 mg tablets. You take it about one hour before sexual activity, and it can help you achieve and maintain an erection sufficient for intercourse. Sildenafil does not work without sexual stimulation and should not be taken more than once a day.

Vedolizumab is a biologic medicine used to treat moderate to severe ulcerative colitis and Crohn's disease, both forms of inflammatory bowel disease (IBD). It is a monoclonal antibody that works by blocking certain white blood cells from entering the gut lining, reducing inflammation. Vedolizumab is given by intravenous infusion in hospital or clinic settings, typically every eight weeks after an initial loading phase. It does not directly affect blood pressure, heart rate, or the enzymes that break down sildenafil, which is why the two medicines are not known to interact in a clinically significant way.

Is there an interaction between sildenafil and vedolizumab?

Based on current evidence and clinical experience, there is no major pharmacological interaction between sildenafil and vedolizumab. Vedolizumab does not inhibit or induce the liver enzymes (particularly CYP3A4) that metabolise sildenafil, so it should not raise or lower sildenafil levels in your bloodstream [3]. Likewise, sildenafil does not interfere with the immune-modulating action of vedolizumab or affect how your body processes the biologic.

That said, it is essential to tell your prescriber about all medicines you are taking, including vedolizumab, during your online consultation. Your prescriber will review your full medication list, your medical history, and any other conditions you have—such as inflammatory bowel disease—to ensure sildenafil is safe and appropriate for you. While the two medicines do not interact directly, your overall health picture matters. For example, if your IBD has caused significant weight loss, malnutrition, or cardiovascular complications, your prescriber will take these factors into account when deciding on the right dose and treatment plan.

Why declaring all your medicines matters

Even when two medicines do not interact with each other, your prescriber needs to know about every treatment you are using. Some people with IBD take additional medicines—such as corticosteroids, immunosuppressants (azathioprine, mercaptopurine), or other biologics—that may have their own considerations. Certain medicines can affect your cardiovascular health, blood pressure, or liver function, all of which are relevant when prescribing sildenafil. By providing a complete and accurate medication history, you help your prescriber make the safest, most effective choice for your ED treatment.

What does your prescriber check before prescribing sildenafil and vedolizumab together?

During your online consultation at Cured Pharmacy, a UK-registered prescriber will review your medical history, current medicines, and any underlying health conditions. They will check that you are not taking any medicines that are contraindicated with sildenafil—such as nitrates (GTN spray, isosorbide mononitrate), nicorandil, riociguat, or recreational drugs known as 'poppers' (amyl or alkyl nitrites). These combinations can cause a dangerous drop in blood pressure and must never be used together [3].

Your prescriber will also ask about your cardiovascular health. Sildenafil can lower blood pressure slightly, so if you take blood-pressure medicines or alpha-blockers (such as tamsulosin or doxazosin), your prescriber will ensure you start on the lowest effective dose and that you are stable on your other treatments. They will review whether you have a history of heart attack, stroke, severe heart failure, or very low blood pressure, as these conditions may mean sildenafil is not suitable or that sexual activity itself is inadvisable [1][2].

Because vedolizumab is used to treat IBD, your prescriber will consider whether your condition is well controlled and whether you have any complications—such as severe anaemia, dehydration, or malnutrition—that could affect your overall fitness for treatment. They will also check for any other medicines you may be taking for IBD or related symptoms, ensuring there are no cumulative risks. This thorough review is a standard part of the prescribing process and helps ensure your safety.

Practical advice for taking sildenafil with vedolizumab

If your prescriber approves sildenafil, you can take it as directed—usually about one hour before sexual activity—on the days you plan to be intimate. Sildenafil works best on an empty stomach or after a light meal; a heavy, fatty meal can delay its effect. You should not take sildenafil more than once in 24 hours. Remember that sexual stimulation is needed for the medicine to work; it will not cause an automatic erection.

Vedolizumab infusions are typically given every eight weeks, and the timing of your sildenafil dose does not need to be adjusted around your infusion schedule. There is no need to avoid sildenafil on the day of your vedolizumab treatment or in the days following. However, if you feel unwell after an infusion—for example, if you experience fatigue, headache, or dizziness—it may be sensible to wait until you feel better before using sildenafil, as you want to be in good general health to enjoy sexual activity.

Avoid drinking large amounts of alcohol when using sildenafil, as alcohol can make it harder to get an erection and can add to the blood-pressure-lowering effect of the medicine, increasing the risk of dizziness or fainting. Grapefruit juice can raise sildenafil levels in your blood and should be avoided. If you develop any new symptoms or side effects—such as severe headache, chest pain, sudden vision or hearing loss, or an erection lasting more than four hours—seek urgent medical help.

Managing your overall health

Living with inflammatory bowel disease can be challenging, and it is not uncommon for chronic illness to affect sexual function and confidence. Fatigue, pain, and the emotional impact of IBD can all contribute to erectile difficulties. Sildenafil can help with the physical aspect of ED, but it is also important to address any underlying concerns with your GP or IBD specialist. They can review your IBD treatment, check for nutritional deficiencies (such as low iron or vitamin D), and refer you for psychological support if needed. A holistic approach—combining effective ED treatment with good IBD control and overall wellbeing—will give you the best chance of a satisfying sex life.

Warning signs and when to seek help with sildenafil and vedolizumab use

While sildenafil is generally well tolerated, you should be aware of certain warning signs that require urgent medical attention. If you experience chest pain or discomfort during or after sexual activity, stop what you are doing and seek immediate help. Do not take nitrate medicines (such as GTN spray) if you have used sildenafil in the past 24 hours, as this combination can cause a life-threatening drop in blood pressure. Call 999 or go to A&E if you have chest pain.

Sudden loss of vision in one or both eyes, or sudden decrease or loss of hearing (sometimes with ringing in the ears or dizziness), are rare but serious side effects of PDE5 inhibitors. If this happens, stop taking sildenafil and seek urgent medical advice. An erection that lasts longer than four hours (priapism) is a medical emergency and requires immediate treatment to prevent permanent damage to the penis. Go to A&E straight away if this occurs.

If you notice any new or worsening symptoms related to your IBD—such as severe abdominal pain, blood in your stools, persistent vomiting, or signs of infection (fever, chills)—contact your IBD team or GP promptly. While these symptoms are not caused by sildenafil, it is important to keep your IBD well controlled and to report any changes in your health. Your prescriber at Cured Pharmacy is also available to answer questions about your ED treatment and can advise you on next steps if you have concerns.

How to get sildenafil safely with vedolizumab at Cured Pharmacy

Cured Pharmacy is a GPhC-registered online pharmacy (GPhC 9012511) offering convenient access to sildenafil and other ED treatments through a secure online consultation. To request sildenafil, you will complete a short health questionnaire covering your medical history, current medicines (including vedolizumab), and any other relevant health information. A UK-registered prescriber will review your answers and, if appropriate, approve your prescription. Your medicine is then dispensed by our pharmacy team and delivered discreetly to your door.

We offer a range of ED treatments to suit different needs and budgets. Sildenafil (generic Viagra) starts at £0.45 per tablet, or £0.36 with your first-order code Ednew. Tadalafil (generic Cialis) is available from £7.95 (£6.36 with code Ednew), and we also stock branded options and alternative PDE5 inhibitors such as vardenafil and avanafil (Spedra). Your prescriber will recommend the most suitable option based on your consultation.

If you have any questions about taking sildenafil with vedolizumab, or if your circumstances change—for example, if you start a new medicine or your IBD treatment is adjusted—you can contact our pharmacy team for advice. We are here to support you in managing your ED safely and effectively, alongside your other health conditions. Remember, if this is the first time you are experiencing erectile difficulties, it is also a good idea to see your GP, as ED can sometimes be an early sign of cardiovascular disease or diabetes [1][2].

Your next steps

If you are ready to explore treatment for erectile dysfunction and you are currently taking vedolizumab, start by completing an online consultation at Cured Pharmacy. Be thorough and honest in your answers, especially about your IBD, any other health conditions, and all the medicines you take. This information allows your prescriber to make a safe, informed decision. Once approved, your sildenafil will be dispensed and posted in plain, discreet packaging. You can reorder easily online whenever you need, and our team is always available to answer questions or update your prescription if your health changes.

Scientific References

1. NHS. (n.d.). Erectile dysfunction (impotence). NHS website. https://www.nhs.uk/conditions/erection-problems-erectile-dysfunction/ [accessed 18 October 2026]
2. National Institute for Health and Care Excellence. (n.d.). Erectile dysfunction. Clinical Knowledge Summaries. https://cks.nice.org.uk/topics/erectile-dysfunction/ [accessed 18 October 2026]
3. Joint Formulary Committee. (n.d.). Sildenafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/sildenafil/ [accessed 18 October 2026]

Information on this page is for educational purposes only and is not medical advice. Prescription treatments require clinical assessment by a UK-registered prescriber. Always consult a qualified healthcare professional before starting or changing any medication.