Vardenafil and Sulfasalazine: Can They Be Taken Together?

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Key takeaways

• No major interaction is commonly reported between vardenafil and sulfasalazine.
• Always declare all current medicines during your online consultation for safety.
• Vardenafil must not be taken with nitrates, nicorandil, riociguat, or poppers.
• Continue sulfasalazine as prescribed and do not stop without medical advice.
• See your GP if you experience new erectile dysfunction, as it can signal underlying health issues.

What Is Vardenafil and How Does It Work?

Vardenafil is a prescription medicine licensed in the UK for the treatment of erectile dysfunction in adult men [5]. 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 more blood to flow in 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, and it should not be taken more than once a day [5]. Like all PDE5 inhibitors, vardenafil only works when you are sexually stimulated—it does not cause an automatic erection. The medicine is available on prescription after a consultation with a UK-registered prescriber, who will check your medical history, current medicines, and overall health to ensure it is safe for you.

What Is Sulfasalazine and Why Is It Prescribed?

Sulfasalazine is a disease-modifying anti-rheumatic drug (DMARD) and anti-inflammatory medicine used to treat several long-term conditions. It is commonly prescribed for ulcerative colitis and Crohn's disease (types of inflammatory bowel disease), as well as rheumatoid arthritis and other inflammatory joint conditions. Sulfasalazine works by reducing inflammation in the gut or joints, helping to control symptoms and prevent flare-ups.

The medicine is usually taken as tablets, often twice a day, and your dose will be tailored to your condition and how well you respond to treatment. Sulfasalazine can affect your blood count and liver function, so your doctor will arrange regular blood tests while you are taking it. It is important to continue taking sulfasalazine as prescribed and not to stop or change your dose without speaking to your doctor, even if you are starting a new medicine for another condition.

At a glance

Is There an Interaction Between Vardenafil and Sulfasalazine?

No major direct interaction is commonly reported between vardenafil and sulfasalazine. The two medicines work in different ways and are broken down by different pathways in the body, so they do not usually interfere with each other's effectiveness or safety. Sulfasalazine is not known to significantly affect the enzymes that break down vardenafil, and vardenafil does not alter the way sulfasalazine works to reduce inflammation.

However, it is still essential that your prescriber knows about all the medicines you are taking, including sulfasalazine, before prescribing vardenafil. This is because your overall health picture—including the condition being treated with sulfasalazine—may influence whether vardenafil is suitable for you. For example, some inflammatory conditions can be associated with cardiovascular risk factors, and your prescriber will want to ensure that sexual activity and the use of a PDE5 inhibitor are safe in your individual case [2].

What Your Prescriber Will Check

During your online consultation at Cured Pharmacy, the prescriber will review your full medical history and all current medicines, including sulfasalazine. They will check for any conditions that might make vardenafil unsuitable, such as recent heart attack or stroke, unstable angina, severe heart failure, very low blood pressure, or a history of sudden vision loss (NAION) [3][5]. They will also look for any other medicines that do interact significantly with vardenafil, such as nitrates, nicorandil, riociguat, alpha-blockers, or potent CYP3A4 inhibitors. If you are stable on sulfasalazine and have no contraindications to vardenafil, the prescriber will usually be able to approve treatment, often starting with the lowest effective dose to ensure safety and tolerability.

Vardenafil and Sulfasalazine: What the Evidence Shows

While there is no specific large-scale study examining the combination of vardenafil and sulfasalazine, clinical experience and pharmacological data suggest that the two can generally be used together without significant problems. Vardenafil is primarily metabolised by the liver enzyme CYP3A4, and to a lesser extent by CYP3A5 and CYP2C [5]. Sulfasalazine, on the other hand, is broken down in the colon by bacteria into its active components and does not significantly inhibit or induce CYP3A4.

It is worth noting that some men with inflammatory bowel disease or rheumatoid arthritis may experience erectile dysfunction as a result of their underlying condition, the psychological impact of living with a long-term illness, or as a side effect of other medicines they are taking. Sulfasalazine itself has been reported in some cases to affect sperm production and fertility in men, but it is not commonly associated with causing erectile dysfunction. If you have noticed changes in your sexual function since starting sulfasalazine or any other medicine, it is important to discuss this with your GP or specialist, as they may be able to adjust your treatment or investigate other contributing factors [1][2].

Practical Advice for Taking Vardenafil with Sulfasalazine

If your prescriber approves vardenafil for you and you are already taking sulfasalazine, there are a few practical steps you can take to use both medicines safely and effectively. First, continue taking sulfasalazine exactly as your doctor has prescribed—do not stop or change your dose without medical advice, as this could lead to a flare-up of your inflammatory condition. Take vardenafil as directed, usually about 25 to 60 minutes before you plan to have sex, and remember that it only works when you are sexually aroused [5].

Be aware of the common side effects of vardenafil, which can include headache, flushing, indigestion, nasal congestion, and dizziness [5]. If you experience dizziness or light-headedness, avoid driving or operating machinery until you know how the medicine affects you. Avoid drinking large amounts of alcohol when taking vardenafil, as this can increase the risk of side effects such as dizziness and low blood pressure, and may also make it harder to get an erection. Grapefruit juice can increase the levels of vardenafil in your blood, so it is best to avoid it while using this medicine.

When to Seek Advice

If you develop any new symptoms or side effects after starting vardenafil, or if you notice that your inflammatory condition is not as well controlled as usual, contact your GP or specialist for advice. You should also speak to a healthcare professional if vardenafil does not work for you, as there may be other treatment options available, including different PDE5 inhibitors (such as sildenafil or tadalafil), alternative doses, or non-tablet treatments. Never take more than the prescribed dose of vardenafil, and do not take it more than once a day, even if it does not seem to be working—taking too much can increase the risk of serious side effects.

Other Medicines and Conditions to Discuss with Your Prescriber

While vardenafil and sulfasalazine do not have a major interaction, it is crucial that your prescriber knows about every medicine you are taking, including over-the-counter products, herbal remedies, and supplements. Some medicines can interact significantly with vardenafil and must not be taken together. These include nitrates (such as GTN spray, isosorbide mononitrate, or isosorbide dinitrate), nicorandil, riociguat, and amyl or alkyl nitrites (poppers)—combining vardenafil with any of these can cause a dangerous drop in blood pressure [3][5]. Do not take vardenafil together with another PDE5 inhibitor, such as sildenafil or tadalafil.

If you are taking an alpha-blocker for an enlarged prostate (such as doxazosin, tamsulosin, or alfuzosin), tell your prescriber, as the combination with vardenafil can increase the risk of dizziness and low blood pressure. You should be stable on the alpha-blocker before starting vardenafil, and your prescriber will usually recommend starting with the lowest dose of the PDE5 inhibitor [5]. Potent CYP3A4 inhibitors, such as ritonavir, cobicistat, ketoconazole, itraconazole, and clarithromycin, can raise vardenafil levels significantly; vardenafil is often contraindicated or requires dose adjustment with these medicines, so your prescriber will check carefully [5]. CYP3A4 inducers, such as rifampicin, carbamazepine, phenytoin, and St John's wort, can reduce the effectiveness of vardenafil. If you have cardiovascular disease, diabetes, high blood pressure, or any other long-term condition, make sure your prescriber is aware, as these may affect whether vardenafil is suitable for you [2].

Seeing Your GP About Erectile Dysfunction

If you are experiencing erectile dysfunction for the first time, it is a good idea to see your GP for a check-up. ED can sometimes be an early warning sign of underlying health problems, such as heart disease, diabetes, or high blood pressure [1][2]. Your GP can carry out tests, review your medicines, and discuss lifestyle factors that may be contributing to the problem, such as smoking, excess alcohol, lack of exercise, or stress. Treating the underlying cause, where possible, can often improve erectile function. Your GP can also refer you to a specialist if needed, or support you in accessing treatment such as PDE5 inhibitors through the NHS or a registered online pharmacy like Cured Pharmacy.

When to get urgent help

• An erection lasting more than 4 hours (priapism) – go to A&E immediately
• Sudden loss of vision in one or both eyes – stop vardenafil and seek urgent medical help
• Sudden decrease or loss of hearing, sometimes with ringing in the ears or dizziness – stop and get medical advice
• Chest pain during or after sex – stop sexual activity and call 999 if the pain does not go away
• Severe allergic reaction (rash, swelling of face or throat, difficulty breathing) – call 999

Call 999 or go to A&E in an emergency, or contact NHS 111 for urgent advice.