Vardenafil and Ustekinumab: Can You Take Them Together?

Vardenafil and Ustekinumab: Understanding the Interaction

Published: 5 November 2026

If you're prescribed ustekinumab for a condition such as psoriasis or Crohn's disease and are considering vardenafil for erectile dysfunction, you may wonder whether vardenafil and ustekinumab 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 combination requires careful review by a prescriber, who will assess your full medical history, current treatments, and overall health to ensure vardenafil is suitable for you.

What Is Vardenafil and How Does It Work?

Vardenafil is a prescription medicine used to treat erectile dysfunction (ED) in men. It belongs to a group of medicines called phosphodiesterase type 5 (PDE5) inhibitors, which also includes sildenafil (Viagra) and tadalafil (Cialis). Vardenafil works by relaxing the blood vessels in the penis, allowing increased blood flow when you are sexually aroused. This helps you achieve and maintain an erection suitable for sexual activity [5].

Vardenafil is available in 5 mg, 10 mg, and 20 mg tablets. The usual starting dose is 10 mg, taken about 25 to 60 minutes before sexual activity. You should not take it more than once a day. Like all PDE5 inhibitors, vardenafil only works when you are sexually stimulated—it does not cause an automatic erection. Common side effects include headache, flushing, indigestion, and nasal congestion [5].

Vardenafil is processed in the body by liver enzymes, particularly one called CYP3A4. This means that medicines which affect this enzyme can change how vardenafil works or increase the risk of side effects. Your prescriber will check all your current medicines, including over-the-counter products and supplements, to ensure vardenafil is safe for you.

What Is Ustekinumab and What Is It Used For?

Ustekinumab is a biologic medicine used to treat certain inflammatory conditions, including moderate to severe plaque psoriasis, psoriatic arthritis, Crohn's disease, and ulcerative colitis. It works by blocking the action of proteins in the immune system called interleukin-12 (IL-12) and interleukin-23 (IL-23), which play a role in inflammation. By reducing this inflammation, ustekinumab helps control the symptoms of these long-term conditions.

Ustekinumab is given as an injection under the skin (subcutaneous injection). The dosing schedule varies depending on the condition being treated and your body weight. For psoriasis, for example, you might receive an initial dose, a second dose four weeks later, and then maintenance doses every 12 weeks. Because ustekinumab affects the immune system, it can increase the risk of infections, so your doctor will monitor you carefully.

Ustekinumab does not directly affect the liver enzymes that process vardenafil, nor does it interact with the blood-vessel-relaxing effects of PDE5 inhibitors. This is why no major interaction between vardenafil and ustekinumab is typically expected. However, your overall health status, including any cardiovascular conditions that may be associated with inflammatory diseases, will be reviewed by your prescriber before starting ED treatment.

Does Ustekinumab Affect Erectile Function?

Chronic inflammatory conditions such as psoriasis and Crohn's disease can themselves be associated with erectile dysfunction, often due to inflammation, psychological stress, or the impact of the condition on overall wellbeing. Some men find that treating the underlying inflammatory condition with medicines like ustekinumab may improve their general health and quality of life, which can indirectly support sexual function. However, ustekinumab itself is not known to cause or worsen erectile dysfunction.

Is There an Interaction Between Vardenafil and Ustekinumab?

No major direct interaction between vardenafil and ustekinumab is commonly reported in clinical practice or listed in standard drug-interaction databases. Vardenafil is a small-molecule medicine processed by liver enzymes, while ustekinumab is a large protein (monoclonal antibody) that is broken down by the body's natural protein-degradation pathways. These two medicines work through entirely different mechanisms and are metabolised in different ways, so they do not typically interfere with each other's activity.

However, the absence of a direct interaction does not mean that vardenafil is automatically suitable for everyone taking ustekinumab. Your prescriber will still need to review your full medical history, including the condition being treated with ustekinumab, any cardiovascular risk factors, and all other medicines you are taking. Conditions such as psoriasis and inflammatory bowel disease can be associated with an increased risk of cardiovascular disease, which is an important consideration when prescribing any ED treatment [1][2].

It is essential to declare all your current medicines—prescription, over-the-counter, and herbal supplements—during your consultation. This allows the prescriber to check for any other potential interactions and to ensure that vardenafil is the right choice for you. Never stop or change a prescribed medicine like ustekinumab without consulting your doctor.

What Does Your Prescriber Check Before Prescribing Vardenafil?

Before prescribing vardenafil, a UK prescriber will carry out a thorough assessment to ensure the medicine is safe and appropriate for you. This includes reviewing your medical history, current health conditions, and all medicines you are taking. The prescriber will ask about cardiovascular health, as ED can be an early warning sign of heart disease or diabetes, and sexual activity itself places demands on the heart [1][2].

Vardenafil must not be taken with certain medicines, including nitrates (such as GTN spray or isosorbide mononitrate), nicorandil, riociguat, or recreational drugs known as 'poppers' (amyl or alkyl nitrites). Combining vardenafil with any of these can cause a dangerous drop in blood pressure. If you take alpha-blockers for an enlarged prostate or high blood pressure (such as tamsulosin or doxazosin), the prescriber will ensure you are stable on that treatment and may start you on a lower dose of vardenafil to reduce the risk of dizziness [5].

The prescriber will also check for medicines that affect the liver enzyme CYP3A4. Potent inhibitors such as ritonavir, cobicistat, ketoconazole, itraconazole, or clarithromycin can raise vardenafil levels in the blood, increasing the risk of side effects. In many cases, vardenafil is avoided or contraindicated when these medicines are used. Conversely, CYP3A4 inducers like rifampicin or St John's wort can reduce vardenafil's effectiveness [5]. Your prescriber will review all these factors to ensure safe use.

Declaring Your Full Medical History

When completing your online consultation at Cured Pharmacy, you will be asked detailed questions about your health, including any long-term conditions, recent heart problems, blood pressure, and all current medicines. Be completely honest and thorough in your answers. This information is reviewed by a UK-registered prescriber, and it is the only way they can assess whether vardenafil is safe for you. If you are taking ustekinumab, make sure to list it along with the condition it treats and any other medicines or supplements you use.

Practical Advice for Taking Vardenafil and Ustekinumab Together

If your prescriber approves vardenafil for you while you are taking ustekinumab, follow the dosing instructions carefully. Take vardenafil about 25 to 60 minutes before you plan to have sex, and do not take more than one dose in 24 hours. Vardenafil works only with sexual stimulation, so it will not cause an erection on its own. Avoid heavy or high-fat meals before taking vardenafil, as these can delay how quickly it works [5].

Continue taking ustekinumab exactly as your doctor has prescribed. Do not stop or change your ustekinumab dose because you are starting ED treatment—these medicines serve different purposes and do not interfere with each other. If you develop any new symptoms or side effects after starting vardenafil, contact your prescriber or GP for advice. Common side effects of vardenafil include headache, flushing, and indigestion, which are usually mild and temporary.

Limit alcohol when using vardenafil, as heavy drinking 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. Avoid grapefruit juice, which can raise vardenafil levels in the blood. If you are prescribed a new medicine by another doctor or buy an over-the-counter product, always check with a pharmacist or your prescriber to ensure it is safe to use with vardenafil.

When to Seek Urgent Medical Help

Most men tolerate vardenafil well, but you should be aware of warning signs that require urgent medical attention. If you experience an erection that lasts longer than four hours (priapism), seek immediate help by going to A&E or calling 999. Priapism is a medical emergency that can cause permanent damage to the penis if not treated promptly [5].

Sudden loss of vision in one or both eyes, or sudden decrease or loss of hearing (which may be accompanied by ringing in the ears or dizziness), are rare but serious side effects. Stop taking vardenafil and seek urgent medical advice if these occur. If you develop chest pain during or after sexual activity, do not continue—stop and seek medical help. Never take a nitrate medicine (such as GTN spray) to relieve chest pain if you have taken vardenafil within the last 24 hours, as this combination can be dangerous [5].

If you experience symptoms of a severe allergic reaction—such as swelling of the face, lips, tongue, or throat, difficulty breathing, or a severe skin rash—call 999 immediately. While taking ustekinumab, you should also be alert for signs of serious infection (such as high fever, persistent cough, or unexplained weight loss) and contact your specialist or GP promptly, as ustekinumab affects the immune system. These are separate concerns, but both are important for your overall safety.

Reporting Side Effects

If you experience any side effects from vardenafil or ustekinumab, you can report them via the Yellow Card Scheme at https://yellowcard.mhra.gov.uk or by searching for the MHRA Yellow Card app. Reporting side effects helps improve the safety information available for all patients. You can also discuss any concerns with your prescriber, GP, or pharmacist.

Scientific References

1. NHS. (n.d.). Erectile dysfunction (impotence). NHS website. https://www.nhs.uk/conditions/erection-problems-erectile-dysfunction/ [accessed 5 November 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 5 November 2026]
3. Joint Formulary Committee. (n.d.). Vardenafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/vardenafil/ [accessed 5 November 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.