Vardenafil and Leflunomide: Can They Be Taken Together?

Vardenafil and Leflunomide: Understanding the Interaction

Published: 1 November 2026

Many men taking leflunomide for rheumatoid arthritis or psoriatic arthritis wonder whether vardenafil and leflunomide can be used together safely. The good news is that no major direct interaction between vardenafil (generic Levitra) and leflunomide is commonly reported in UK prescribing guidance. However, both medicines can affect blood pressure and liver function, so your prescriber will carry out important safety checks during your consultation to ensure the combination is suitable for you.

What is vardenafil and leflunomide used for?

Vardenafil is a prescription medicine used to treat erectile dysfunction (ED) in adult men [5]. It belongs to a group of medicines called PDE5 inhibitors, which work by relaxing blood vessels in the penis, allowing increased blood flow when you are sexually aroused. Vardenafil is available in 5 mg, 10 mg, and 20 mg tablets and is usually taken about 25 to 60 minutes before sexual activity. You should not take it more than once a day, and it only works when you are sexually stimulated [5].

Leflunomide is an immunosuppressant medicine prescribed for active rheumatoid arthritis and psoriatic arthritis. It works by reducing the activity of your immune system to slow down joint damage and reduce inflammation. Leflunomide is taken as a daily tablet, and because it stays in your body for a long time, regular blood tests are needed to monitor your liver function and blood count. Both vardenafil and leflunomide require careful prescribing, so it is essential that your doctor or prescriber knows about all the medicines you take.

Is there a direct interaction between vardenafil and leflunomide?

There is no well-documented direct pharmacological interaction between vardenafil and leflunomide in UK prescribing resources [5][12]. This means that the two medicines do not typically interfere with each other's metabolism or effectiveness in a way that would make the combination unsafe for most people. However, this does not mean the combination is automatically suitable for everyone.

Both medicines can have effects that need to be considered together. Vardenafil can lower blood pressure slightly, and leflunomide has been associated with increases in blood pressure in some patients. Your prescriber will assess your individual blood pressure control and cardiovascular health during your consultation. Additionally, leflunomide can affect liver function, and while vardenafil is generally well tolerated, any pre-existing liver condition may influence whether it is the right ED treatment for you. Your prescriber will review your recent blood test results and medical history to ensure the combination is safe.

How the medicines work in your body

Vardenafil is broken down mainly by liver enzymes, particularly CYP3A4 [5]. Leflunomide is also processed by the liver and is converted into an active metabolite that remains in the body for weeks. Because both medicines involve liver metabolism, your prescriber will check that your liver function is normal before prescribing vardenafil. If you are taking leflunomide, you will already be having regular liver function tests as part of your rheumatology care, and your prescriber may ask for recent results to confirm it is safe to add vardenafil.

What does your prescriber check before prescribing vardenafil and leflunomide together?

When you request vardenafil through an online consultation at Cured Pharmacy, the UK-registered prescriber will ask detailed questions about your current medicines, including leflunomide. They will check your blood pressure history, cardiovascular health, and any recent blood test results, particularly liver function tests. Because leflunomide requires regular monitoring, your prescriber may ask when your last tests were done and whether there have been any concerns raised by your rheumatologist or GP.

The prescriber will also confirm that you are not taking any medicines that are contraindicated with vardenafil. These include nitrates (such as GTN spray or isosorbide mononitrate), nicorandil, riociguat, and recreational drugs known as poppers (amyl or alkyl nitrites). Combining vardenafil with any of these can cause a dangerous drop in blood pressure, so do not take them together [5]. If you are on other blood-pressure medicines, such as alpha-blockers (for example, tamsulosin or doxazosin), your prescriber will ensure you are stable on that treatment and may start you on the lowest dose of vardenafil.

You should also tell your prescriber about any other medicines you take, including over-the-counter products and herbal supplements. For example, potent CYP3A4 inhibitors like ketoconazole, itraconazole, ritonavir, or clarithromycin can increase vardenafil levels in your blood, and vardenafil is contraindicated or requires dose adjustment with these medicines [5]. St John's wort and some anti-epileptic drugs can reduce vardenafil's effectiveness. Your prescriber will review every medicine during your consultation to ensure safety.

Practical advice for taking vardenafil with leflunomide

If your prescriber approves vardenafil, take it as directed—usually about 25 to 60 minutes before you plan to have sex [5]. Swallow the tablet whole with water, with or without food, though a heavy or high-fat meal may delay how quickly it works. Do not take more than one dose in 24 hours. Remember that vardenafil only works when you are sexually aroused; it is not an aphrodisiac and will not cause an automatic erection.

Continue taking your leflunomide exactly as prescribed by your rheumatologist or GP. Do not stop or change the dose without medical advice, as this could affect your arthritis control. Keep up with your regular blood test appointments so that your liver function and blood count are monitored. If you notice any new symptoms—such as unusual tiredness, yellowing of the skin or eyes, dark urine, or unexplained bruising—contact your doctor promptly, as these could indicate a problem with your liver or blood count.

Avoid drinking large amounts of alcohol when using vardenafil, as alcohol can worsen erectile dysfunction and add to the blood-pressure-lowering effect, increasing the risk of dizziness or fainting [5]. Grapefruit juice can raise vardenafil levels in your blood, so it is best to avoid it. If you experience dizziness, particularly when standing up, sit or lie down until it passes, and let your prescriber know at your next review.

When to contact your doctor

Seek urgent medical help if you develop an erection that lasts longer than four hours (priapism), sudden loss of vision in one or both eyes, or sudden decrease or loss of hearing [5]. These are rare but serious side effects. If you experience chest pain during or after sex, do not use nitrate medicines such as GTN spray; instead, call 999 or go to A&E immediately and tell the healthcare team you have taken vardenafil. If you develop new or worsening symptoms while taking leflunomide—such as severe infection, breathing problems, or skin rash—contact your GP or rheumatology team the same day.

Can vardenafil and leflunomide affect blood pressure?

Vardenafil can cause a small decrease in blood pressure, which is usually not a problem for most men [5]. However, leflunomide has been reported to cause high blood pressure (hypertension) in some people. Your prescriber will ask about your blood pressure history and any current blood-pressure medicines during your consultation. If your blood pressure is well controlled, the combination of vardenafil and leflunomide is usually manageable, but your prescriber may recommend that you monitor your blood pressure at home or have it checked regularly by your GP.

If you are also taking medicines for high blood pressure, such as ACE inhibitors, angiotensin receptor blockers, calcium channel blockers, or beta-blockers, these can add to the blood-pressure-lowering effect of vardenafil. This does not mean you cannot use vardenafil, but your prescriber will assess your overall cardiovascular health and may start you on a lower dose. Alpha-blockers (used for prostate symptoms or high blood pressure) require particular caution: you should be stable on the alpha-blocker before starting vardenafil, and you will usually start on the lowest dose of vardenafil to minimise the risk of dizziness or fainting [5].

If you feel dizzy, light-headed, or faint after taking vardenafil, avoid driving or operating machinery, and sit or lie down until the symptoms pass. Let your prescriber know so they can review your dose or consider an alternative ED treatment. Always declare all your current medicines, including those prescribed by different doctors, during your online consultation.

Are there alternative ED treatments if vardenafil is not suitable?

If your prescriber has any concerns about vardenafil and leflunomide in your individual case, there are other licensed ED treatments available in the UK [1][2]. Sildenafil (generic Viagra) and tadalafil (generic Cialis) are also PDE5 inhibitors and work in a similar way to vardenafil. Sildenafil is taken about one hour before sex and lasts for around four to six hours, while tadalafil can be taken on-demand (working within 30 minutes and lasting up to 36 hours) or as a lower-dose daily tablet [3][4]. Avanafil (Spedra) is another option that works quickly, usually within 15 to 30 minutes [6].

All PDE5 inhibitors have similar precautions regarding blood pressure, liver function, and drug interactions, so the same safety checks apply. Your prescriber will help you choose the most suitable option based on your health, preferences, and how you respond to treatment. If PDE5 inhibitors are not suitable or effective for you, other treatments such as alprostadil (available as a cream applied to the tip of the penis or as an injection) may be considered, though these require a face-to-face assessment and are used less commonly [7].

At Cured Pharmacy, all ED treatments are prescription-only and are supplied after an online consultation reviewed by a UK-registered prescriber. The prescriber will take into account your leflunomide treatment, your arthritis, and any other health conditions to recommend the safest and most effective option for you. If you have not seen a GP about your ED, it is a good idea to do so, as ED can sometimes be an early sign of underlying conditions such as diabetes or heart disease [1].

Lifestyle measures that can help

Alongside medication, lifestyle changes can improve erectile function and overall health [1][2]. Maintaining a healthy weight, eating a balanced diet, taking regular exercise, and not smoking can all make a difference. Managing stress and getting enough sleep are also important, as fatigue and anxiety can contribute to ED. If your arthritis limits your physical activity, speak to your rheumatology team or a physiotherapist about exercises that are safe and suitable for you. Reducing alcohol intake and avoiding recreational drugs will also help both your ED treatment and your general health.

Scientific References

1. NHS. (n.d.). Erectile dysfunction (impotence). NHS website. https://www.nhs.uk/conditions/erection-problems-erectile-dysfunction/ [accessed 1 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 1 November 2026]
3. Joint Formulary Committee. (n.d.). Sildenafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/sildenafil/ [accessed 1 November 2026]
4. Joint Formulary Committee. (n.d.). Tadalafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/tadalafil/ [accessed 1 November 2026]
5. Joint Formulary Committee. (n.d.). Vardenafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/vardenafil/ [accessed 1 November 2026]
6. Joint Formulary Committee. (n.d.). Avanafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/avanafil/ [accessed 1 November 2026]
7. Joint Formulary Committee. (n.d.). Alprostadil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/alprostadil/ [accessed 1 November 2026]
8. Electronic Medicines Compendium. (n.d.). Summaries of Product Characteristics and Patient Information Leaflets. https://www.medicines.org.uk/emc/ [accessed 1 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.