Vardenafil and Dimethyl Fumarate: Can They Be Taken Together?

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Vardenafil and Dimethyl Fumarate: Understanding the Interaction

Published: 29 October 2026

If you're prescribed dimethyl fumarate for multiple sclerosis and considering vardenafil for erectile dysfunction, you may wonder whether vardenafil and dimethyl fumarate 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, your prescriber will still review your full medical history and all current medicines during your consultation to ensure vardenafil is suitable for you, as individual circumstances vary.

What is vardenafil and how does it work?

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 also includes sildenafil (Viagra), tadalafil (Cialis), and avanafil (Spedra). Vardenafil is the generic version of the branded medicine Levitra.

When you're sexually aroused, your body releases a chemical messenger called nitric oxide, which helps blood vessels in the penis relax and widen. This increased blood flow allows an erection to occur. An enzyme called phosphodiesterase type 5 (PDE5) can break down the substances that keep blood vessels relaxed. Vardenafil works by blocking PDE5, helping blood vessels stay open longer and making it easier to get and maintain an erection when you're sexually stimulated [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. It should not be taken more than once a day. Vardenafil only works when you're sexually aroused—it won't cause an erection on its own [5].

What is dimethyl fumarate and what is it used for?

Dimethyl fumarate is a prescription medicine used to treat relapsing-remitting multiple sclerosis (MS), a long-term condition affecting the brain and spinal cord. It's sold under the brand name Tecfidera in the UK. Dimethyl fumarate is taken as a capsule, usually twice a day with food.

The exact way dimethyl fumarate works in MS isn't fully understood, but it's thought to reduce inflammation and protect nerve cells from damage. It helps reduce the number of relapses (flare-ups of MS symptoms) and may slow the progression of disability in people with relapsing-remitting MS.

Common side effects of dimethyl fumarate include flushing (redness and warmth of the skin), stomach problems such as diarrhoea, nausea, and abdominal pain, and a temporary drop in white blood cell count. Your doctor will monitor your blood counts regularly while you're taking this medicine. Dimethyl fumarate does not directly affect blood pressure or the enzymes that break down vardenafil.

Is there an interaction between vardenafil and dimethyl fumarate?

No major direct interaction between vardenafil and dimethyl fumarate is commonly reported in clinical practice or listed in standard UK drug interaction databases. These two medicines work through different mechanisms in the body and are not known to interfere with each other's effectiveness or increase the risk of side effects when taken together.

Dimethyl fumarate does not significantly affect the liver enzymes (particularly CYP3A4) that break down vardenafil, so it should not raise or lower vardenafil levels in your blood. Similarly, vardenafil does not interfere with how dimethyl fumarate works to manage multiple sclerosis.

However, this does not mean the combination is automatically suitable for everyone. Your prescriber will still need to review your full medical history, current medicines, and overall health during your consultation. Erectile dysfunction can sometimes be linked to other health conditions, and MS itself or other medicines you're taking may need to be considered. Always declare all your medicines—including over-the-counter products and supplements—when you request vardenafil.

What your prescriber will check

Even though vardenafil and dimethyl fumarate do not interact directly, your prescriber will check that vardenafil is safe for you overall. They'll ask about your heart health, blood pressure, any history of stroke or heart attack, and whether you take nitrates, nicorandil, or other medicines that can interact dangerously with PDE5 inhibitors. They'll also consider whether MS or any related symptoms affect your ability to engage in sexual activity safely. If you're on other medicines for MS, blood pressure, or any other condition, your prescriber will review those too to ensure there are no concerns.

Medicines that do interact with vardenafil and dimethyl fumarate

While vardenafil and dimethyl fumarate can usually be taken together, it's important to know which medicines do interact with each of them. For vardenafil, the most serious interactions are with nitrates (such as GTN spray, isosorbide mononitrate, or isosorbide dinitrate), nicorandil, riociguat, and amyl or alkyl nitrites (poppers). Do not take vardenafil with any of these medicines, as the combination can cause a dangerous drop in blood pressure [5].

Vardenafil should also not be taken with another PDE5 inhibitor (such as sildenafil, tadalafil, or avanafil) at the same time. Potent CYP3A4 inhibitors—including ritonavir, cobicistat, ketoconazole, itraconazole, and clarithromycin—can raise vardenafil levels significantly, and vardenafil is contraindicated or requires dose adjustment with these medicines [5]. Alpha-blockers (such as doxazosin or tamsulosin) can also interact, causing low blood pressure or dizziness; if you take an alpha-blocker, you should be stable on it and start vardenafil at the lowest dose.

For dimethyl fumarate, there are no widely recognised major drug interactions, but your doctor will monitor your blood counts and kidney function regularly. If you're on other immunosuppressant medicines, your doctor will consider the overall effect on your immune system. Always tell your prescriber and pharmacist about every medicine you take, including herbal remedies like St John's wort, which can reduce the effectiveness of vardenafil.

Practical advice for taking vardenafil with dimethyl fumarate

If your prescriber confirms that vardenafil is suitable for you, take it about 25 to 60 minutes before you plan to have sex. Swallow the tablet whole with water. You can take vardenafil 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 [5].

Continue taking your dimethyl fumarate exactly as prescribed—usually twice a day with food. There's no need to time your dimethyl fumarate doses around when you take vardenafil. Keep taking both medicines as directed unless your doctor advises otherwise.

Be aware of common side effects. Vardenafil can cause headache, flushing, indigestion, nasal congestion, or dizziness. Dimethyl fumarate often causes flushing and stomach upset, especially in the first few weeks. If you experience flushing from both medicines, it may be more noticeable, but this is usually harmless and tends to improve over time. Drink plenty of water and avoid heavy alcohol, which can worsen ED and add to dizziness or low blood pressure.

When to seek help

Seek urgent medical help if you have an erection lasting more than four hours (priapism), sudden loss of vision or hearing, or chest pain during sex. These are rare but serious side effects of vardenafil that need immediate attention [5]. If you develop new or worsening symptoms related to your MS, or unusual side effects from dimethyl fumarate (such as severe stomach pain, signs of infection, or unexplained bruising), contact your MS specialist or GP promptly. Do not stop taking dimethyl fumarate without medical advice.

How to get vardenafil from Cured Pharmacy

Vardenafil is a prescription-only medicine in the UK, so you'll need a consultation with a prescriber before it can be supplied. At Cured Pharmacy, the process is straightforward and discreet. You complete a short online health questionnaire covering your medical history, current medicines (including dimethyl fumarate), and any other relevant health information. A UK-registered prescriber reviews your answers to ensure vardenafil is safe and suitable for you.

If approved, your medicine is dispensed by our GPhC-registered pharmacy (GPhC 9012511) and delivered discreetly to your door. Vardenafil (generic Levitra) is available from £16.95, or £13.56 for your first order with code Ednew. We also offer other PDE5 inhibitors, including sildenafil from £0.45 (£0.36 with code Ednew) and tadalafil from £7.95 (£6.36 with code Ednew), if your prescriber recommends an alternative.

If you have any questions about taking vardenafil with dimethyl fumarate or any other medicine, our pharmacist-led team is here to help. We're committed to providing safe, evidence-based care and supporting you in managing both your erectile dysfunction and your overall health. Remember, if you're experiencing new erectile dysfunction, it's also worth seeing your GP, as ED can sometimes be an early sign of heart disease or diabetes [1].

Why choose Cured Pharmacy?

Cured Pharmacy is a fully registered online pharmacy (GPhC 9012511) with experienced UK prescribers and pharmacists. We offer clear, honest advice, discreet service, and genuine care. Every consultation is reviewed individually, so you can be confident that your treatment plan takes your full medical history—including your dimethyl fumarate—into account. We're here to make accessing ED treatment straightforward, safe, and supportive.

Scientific References

1. NHS. (n.d.). Erectile dysfunction (impotence). NHS website. https://www.nhs.uk/conditions/erection-problems-erectile-dysfunction/ [accessed 29 October 2026]
2. Joint Formulary Committee. (n.d.). Vardenafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/vardenafil/ [accessed 29 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.

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