Vardenafil and Relugolix: Can You Take Them Together?

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Vardenafil and Relugolix: Understanding the Interaction

Published: 3 November 2026

If you're considering vardenafil and relugolix together, you'll want to know whether it's safe and what your prescriber will check. Vardenafil is a PDE5 inhibitor used to treat erectile dysfunction, while relugolix is a hormone therapy used primarily for prostate cancer and, in combination products, for uterine fibroids. This page explains how these medicines work, whether they interact, and the practical steps your healthcare team will take to ensure your treatment is safe and effective.

What Is Vardenafil and How Does It Work?

Vardenafil (generic Levitra) is a prescription medicine licensed in the UK to treat erectile dysfunction (ED). It belongs to a class of medicines called phosphodiesterase type 5 (PDE5) inhibitors, which work by relaxing blood vessels in the penis, allowing increased blood flow when you're sexually aroused [5]. Vardenafil is available in 5mg, 10mg, and 20mg tablets and is typically taken about 25 to 60 minutes before sexual activity. The effect can last for several hours, but you'll need sexual stimulation for the medicine to work.

Like all PDE5 inhibitors, vardenafil does not cure ED; it helps you achieve and maintain an erection sufficient for sexual activity when you're aroused [1]. Common side effects include headache, flushing, nasal congestion, and indigestion. Vardenafil is only available on prescription in the UK after a clinical assessment by a registered prescriber, who will check your medical history, current medicines, and overall suitability. At Cured Pharmacy, our online consultation is reviewed by a UK prescriber to ensure vardenafil is safe and appropriate for you.

What Is Relugolix and What Is It Used For?

Relugolix is a gonadotropin-releasing hormone (GnRH) receptor antagonist, a type of hormone therapy. In the UK, it is licensed for the treatment of advanced hormone-sensitive prostate cancer. Relugolix works by blocking GnRH receptors in the pituitary gland, which in turn reduces the production of testosterone and other sex hormones. Lowering testosterone levels can slow the growth of prostate cancer cells that depend on these hormones.

Relugolix is also available in combination with oestradiol and norethisterone acetate (brand name Ryeqo) for the treatment of moderate to severe symptoms of uterine fibroids in women of reproductive age. The prostate cancer formulation is a single-agent tablet taken once daily. Because relugolix significantly lowers testosterone, men taking it may experience side effects related to low hormone levels, including reduced libido, erectile dysfunction, hot flushes, fatigue, and changes in mood. It's important to discuss all your current medicines with your prescriber, as relugolix can interact with certain drugs, particularly those affecting the P-glycoprotein transporter.

Why Men on Relugolix May Seek ED Treatment

Because relugolix lowers testosterone as part of its therapeutic action, erectile dysfunction is a recognised and common side effect of the treatment. Men undergoing hormone therapy for prostate cancer often experience a significant reduction in sexual function and libido. For some men, maintaining sexual activity remains an important part of quality of life, and they may wish to explore treatment options for ED. This is where medicines like vardenafil may be considered, provided they are safe to use alongside relugolix and any other treatments the patient is receiving.

Do Vardenafil and Relugolix Interact with Each Other?

There is no major direct drug interaction commonly reported between vardenafil and relugolix. These two medicines work through different mechanisms: vardenafil acts locally on blood vessels in the penis via PDE5 inhibition, while relugolix works centrally on the pituitary gland to suppress hormone production. Neither medicine is known to significantly affect the metabolism or action of the other through common pathways such as cytochrome P450 enzymes or P-glycoprotein in a way that would create a dangerous interaction.

However, it's important to understand that the absence of a major pharmacological interaction does not automatically mean the combination is suitable for everyone. Men taking relugolix often have prostate cancer and may have other health conditions or be taking additional medicines that do interact with vardenafil. Your prescriber will assess your full medical history, including your cardiovascular health, blood pressure, and all current medicines, to determine whether vardenafil is safe for you. The online consultation at Cured Pharmacy is designed to capture this information and ensure a UK prescriber reviews your individual circumstances before any prescription is issued.

What Your Prescriber Will Check Before Prescribing Vardenafil

When you request vardenafil, your prescriber will conduct a thorough assessment to ensure it is safe and appropriate. They will ask about your cardiovascular health, including any history of heart attack, stroke, angina, heart failure, or abnormal heart rhythms. PDE5 inhibitors like vardenafil can lower blood pressure slightly, so your prescriber needs to know if you have very low blood pressure or are taking medicines that also affect blood pressure, such as alpha-blockers (e.g. doxazosin, tamsulosin) or other antihypertensives [5].

Your prescriber will also check for absolute contraindications. You must not take vardenafil if you are using nitrates (such as GTN spray, isosorbide mononitrate or dinitrate), nicorandil, riociguat, or recreational drugs known as 'poppers' (amyl or alkyl nitrites), as the combination can cause a dangerous drop in blood pressure. You also cannot take vardenafil alongside another PDE5 inhibitor (sildenafil, tadalafil, or avanafil). If you are taking potent CYP3A4 inhibitors—such as ritonavir, cobicistat, ketoconazole, itraconazole, or clarithromycin—vardenafil is usually contraindicated or requires significant dose adjustment, and your prescriber will review the Summary of Product Characteristics (SmPC) carefully [5][12].

Your prescriber will ask about any history of sudden vision loss (non-arteritic anterior ischaemic optic neuropathy, or NAION), inherited retinal disorders, severe liver or kidney disease, and whether sexual activity is advisable given your overall health. They will also want to know about all your current medicines, including over-the-counter products and supplements, to check for interactions. If you are taking relugolix, your prescriber will consider your underlying condition (prostate cancer), your overall fitness for sexual activity, and any other treatments you are receiving.

Special Considerations for Men with Prostate Cancer

Men with prostate cancer may have additional health considerations that affect the suitability of ED treatment. Your prescriber will want to ensure that sexual activity is safe for you, particularly if you have cardiovascular disease or other comorbidities. They may also consider whether your cancer treatment plan includes other medicines that could interact with vardenafil. It's essential to be open and honest during your consultation about your diagnosis, treatment goals, and overall health so that your prescriber can make an informed decision. If vardenafil is not suitable, your prescriber may discuss alternative options or refer you back to your GP or specialist for further advice.

Practical Advice for Taking Vardenafil and Relugolix Together

If your prescriber determines that vardenafil is safe for you while you are taking relugolix, follow the dosing instructions carefully. Vardenafil is usually taken about 25 to 60 minutes before you plan to have sex, and you should not take more than one dose in 24 hours [5]. Sexual stimulation is necessary for the medicine to work. You can take vardenafil with or without food, but a heavy or high-fat meal may delay its effect.

Avoid drinking large amounts of alcohol, as this can make erectile dysfunction worse and increase the risk of side effects such as dizziness and low blood pressure. Grapefruit juice can raise vardenafil levels in your blood and should be avoided. Do not use recreational drugs, especially 'poppers', as the combination with vardenafil can be life-threatening. If you experience side effects such as severe headache, dizziness, or visual disturbances, speak to your pharmacist or doctor.

Continue taking relugolix exactly as prescribed by your oncologist or specialist. Do not stop or change the dose of either medicine without medical advice. If you develop new symptoms, start a new medicine, or have any concerns about how your treatments are working together, contact your GP, specialist, or pharmacist promptly. At Cured Pharmacy, our team is available to answer questions and provide support throughout your treatment.

When to Seek Urgent Medical Help

While vardenafil is generally well tolerated, there are some rare but serious side effects that require immediate medical attention. If you develop an erection that lasts longer than four hours (priapism), seek emergency help straight away by calling 999 or going to A&E. Priapism can cause permanent damage to the penis if not treated promptly. 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 also medical emergencies and require urgent assessment [5].

If you experience chest pain during or after sexual activity, stop and seek medical help immediately. Chest pain could be a sign of a heart problem, and you should not take another dose of vardenafil until you have been assessed by a doctor. Do not take nitrate medicines (such as GTN spray) for chest pain if you have taken vardenafil, as this combination can cause a severe drop in blood pressure. If you have any severe allergic reaction (such as swelling of the face, lips, tongue, or throat, or difficulty breathing), call 999.

If you are taking relugolix and vardenafil together and notice any new or worsening symptoms—such as severe dizziness, fainting, unusual fatigue, or changes in urination—contact your GP or specialist the same day. Always inform any healthcare professional treating you that you are taking both medicines, especially in an emergency situation.

Reporting Side Effects

If you experience side effects from vardenafil or relugolix, you can report them via the UK Yellow Card Scheme at https://yellowcard.mhra.gov.uk or by searching for 'Yellow Card' in the Google Play or Apple App Store. Reporting side effects helps improve the safety information available for all patients. You can also discuss any concerns with your pharmacist or prescriber, who can offer advice and, if necessary, adjust your treatment.

Scientific References

1. NHS. (n.d.). Erectile dysfunction (impotence). NHS website. https://www.nhs.uk/conditions/erection-problems-erectile-dysfunction/ [accessed 3 November 2026]
2. Joint Formulary Committee. (n.d.). Vardenafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/vardenafil/ [accessed 3 November 2026]
3. Electronic Medicines Compendium. (n.d.). Summaries of Product Characteristics and Patient Information Leaflets. https://www.medicines.org.uk/emc/ [accessed 3 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.