Vardenafil and Itraconazole: Can They Be Taken Together?

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What is vardenafil and how does it work?

Vardenafil (also known by the brand name Levitra) is a prescription medicine used to treat erectile dysfunction in men. 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 [5].

Vardenafil is available in 5mg, 10mg and 20mg tablets and is usually taken about 25 to 60 minutes before sexual activity. The effect can last for several hours, but the medicine only works when you are sexually stimulated – it does not cause an automatic erection [5].

Like all PDE5 inhibitors, vardenafil is broken down in the body by an enzyme called CYP3A4. When other medicines block this enzyme, vardenafil stays in the bloodstream much longer and at much higher levels than intended, which is why certain drug interactions can be dangerous [5].

What is itraconazole and why is it prescribed?

Itraconazole is a prescription antifungal medicine used to treat a range of fungal infections, including nail infections, skin infections such as athlete's foot and ringworm, and more serious internal fungal infections. It works by stopping fungi from producing a substance called ergosterol, which is essential for their cell walls [12].

Itraconazole is available as capsules, oral liquid and intravenous infusion. The dose and duration of treatment depend on the type and severity of the infection. Some fungal infections require several weeks or even months of treatment to clear completely [12].

Importantly, itraconazole is classified as a potent CYP3A4 inhibitor. This means it strongly blocks the enzyme that breaks down many other medicines in the body, including vardenafil. This blocking effect can cause significant increases in the blood levels of medicines that rely on CYP3A4 for their elimination, leading to a much higher risk of side effects [12].

Common uses of itraconazole

Itraconazole is prescribed for fungal nail infections (onychomycosis), vaginal thrush that keeps coming back, pityriasis versicolor (a skin condition causing patches of discoloured skin), tinea infections of the skin, and systemic fungal infections in people with weakened immune systems. Your doctor will choose itraconazole when other antifungal treatments are not suitable or have not worked [12].

When to get urgent help

• An erection lasting more than 4 hours (priapism) – go to A&E immediately
• Sudden loss of vision or hearing – seek urgent medical attention
• Severe dizziness, fainting, or chest pain after taking vardenafil – call 999
• Symptoms of a severe allergic reaction such as swelling of the face, lips or throat, or difficulty breathing – call 999

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

Why vardenafil and itraconazole should not be taken together

The combination of vardenafil and itraconazole is contraindicated, meaning these medicines should not be used together. Itraconazole is a potent inhibitor of the CYP3A4 enzyme, which is the main pathway the body uses to break down and eliminate vardenafil from the bloodstream [5].

When itraconazole blocks this enzyme, vardenafil levels can rise to many times higher than normal. This dramatically increases the risk of serious side effects, including severe drops in blood pressure, prolonged erections (priapism), visual disturbances, and cardiovascular events. The Summary of Product Characteristics for vardenafil specifically lists potent CYP3A4 inhibitors such as itraconazole as contraindications [5][12].

Even a single dose of itraconazole can have a prolonged effect on the CYP3A4 enzyme, lasting several days after you stop taking it. This means the interaction risk continues for some time after finishing a course of itraconazole. Your prescriber will need to assess how long to wait before it is safe to start vardenafil, based on your individual circumstances and the duration of your antifungal treatment.

What your prescriber checks during your consultation

When you request treatment for erectile dysfunction, your prescriber will ask detailed questions about all the medicines you are currently taking, including prescription medicines, over-the-counter treatments, and herbal supplements. This is essential to identify any potential drug interactions before prescribing a PDE5 inhibitor [2].

If you are taking itraconazole or have recently finished a course, your prescriber will not prescribe vardenafil. They will discuss alternative erectile dysfunction treatments that do not have the same interaction risk, such as sildenafil or tadalafil at carefully adjusted doses, or they may recommend waiting until the itraconazole has cleared from your system [3][4][5].

Your prescriber will also check for other contraindications to PDE5 inhibitors, including use of nitrate medicines (such as GTN spray for angina), recent heart attack or stroke, severe heart failure, very low blood pressure, and certain eye conditions. They will review your cardiovascular health to ensure that sexual activity is safe for you [2][5].

Information to provide during your consultation

Always tell your prescriber the exact name and dose of any antifungal medicine you are taking or have recently taken, how long you have been on it, and when you are due to finish the course. Also mention any other medicines that might affect liver enzymes, including antibiotics like clarithromycin, HIV medicines, and herbal remedies such as St John's wort. Being open and accurate about your medication history helps your prescriber choose the safest and most effective treatment for you [2].

At a glance

Safer alternatives to vardenafil when taking itraconazole

If you need treatment for erectile dysfunction while taking itraconazole, your prescriber may consider sildenafil or tadalafil instead of vardenafil. While these medicines are also affected by CYP3A4 inhibitors, they are not absolutely contraindicated in the same way – instead, the dose can be carefully reduced to account for the interaction [3][4].

For sildenafil, the usual starting dose is 50mg, but when taken with a potent CYP3A4 inhibitor like itraconazole, your prescriber may start you on 25mg and monitor your response closely. For tadalafil, the maximum recommended dose is reduced (for example, 10mg in 72 hours for on-demand use), and daily tadalafil is generally not recommended during treatment with itraconazole [3][4].

Your prescriber will weigh up the benefits and risks based on your individual situation, including how long you need to take itraconazole, the severity of your erectile dysfunction, and your overall health. In some cases, it may be safest to wait until you have finished your antifungal treatment before starting any PDE5 inhibitor. Never adjust doses yourself or take medicines not prescribed for you [2].

Practical advice if you are prescribed both medicines

If you have been prescribed vardenafil and your doctor later prescribes itraconazole (or another potent CYP3A4 inhibitor such as ketoconazole or clarithromycin), contact your prescriber or pharmacist immediately before taking the new medicine. Do not assume it is safe to continue both – the interaction can be serious [5][12].

Similarly, if you are taking itraconazole and considering treatment for erectile dysfunction, declare this during your online consultation. The prescriber reviewing your request needs this information to make a safe decision. Withholding details about your current medicines puts your health at risk and may lead to a prescription that is not safe for you [2].

Other antifungal medicines, such as fluconazole, also inhibit CYP3A4 but to a lesser degree than itraconazole. Your prescriber will check the specific antifungal you are taking and adjust your ED treatment accordingly. Always read the patient information leaflet that comes with any new medicine and ask your pharmacist if you have questions about interactions. If you experience unexpected side effects – such as dizziness, fainting, visual changes, or a prolonged erection lasting more than four hours – seek medical help immediately [2][5].

What to do if you have already taken both medicines together

If you have taken vardenafil while on itraconazole, monitor yourself closely for side effects such as severe headache, dizziness, fainting, visual disturbances, or chest pain. If you experience any of these symptoms, seek medical advice promptly. Contact NHS 111 for guidance, or call 999 if symptoms are severe. Do not take another dose of vardenafil until you have spoken to a healthcare professional. Going forward, ensure your prescriber and pharmacist have a complete list of all your medicines to prevent similar interactions [2].

In summary

• Vardenafil and itraconazole must not be taken together due to a serious drug interaction.
• Itraconazole raises vardenafil levels significantly, increasing the risk of dangerous side effects.
• Safer alternatives such as adjusted-dose sildenafil or tadalafil may be considered by your prescriber.
• Always declare all current medicines during your erectile dysfunction consultation.
• Contact a healthcare professional immediately if you have taken both medicines together.

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