Vardenafil and Aciclovir: Can You Take Them Together?

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Vardenafil and Aciclovir: Understanding the Interaction

Published: 27 October 2026

Many men wonder whether vardenafil and aciclovir can be taken together safely. The good news is that no major interaction is commonly reported between vardenafil (a medicine for erectile dysfunction) and aciclovir (an antiviral medicine used to treat cold sores, shingles, and genital herpes). However, every medicine you take must be declared during your consultation, so your prescriber or pharmacist can check your full medication list and medical history to ensure treatment is safe and suitable for you.

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) and tadalafil (Cialis). Vardenafil is the generic version of Levitra and works 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 [5]. The medicine only works when you are sexually stimulated—it does not cause an automatic erection. The effect can last for several hours, but you should not take more than one dose in 24 hours. Like all PDE5 inhibitors, vardenafil requires a prescription and is only supplied after an online consultation reviewed by a UK-registered prescriber.

What Is Aciclovir and What Is It Used For?

Aciclovir is an antiviral medicine used to treat infections caused by the herpes simplex virus and varicella-zoster virus [12]. It is commonly prescribed for cold sores, genital herpes, shingles, and chickenpox. Aciclovir works by stopping the virus from multiplying, which helps your body fight the infection and reduces the severity and duration of symptoms.

Aciclovir is available as tablets, cream, and eye ointment. The tablets are usually taken two to five times a day, depending on the condition being treated. Some people take aciclovir regularly to prevent recurrent herpes infections. It is generally well tolerated, though side effects can include nausea, headache, and occasionally dizziness. Aciclovir does not cure herpes infections but helps manage outbreaks and reduce transmission risk.

How Aciclovir Works in the Body

Aciclovir is converted into an active form inside cells infected with the herpes virus. Once activated, it interferes with the virus's ability to copy its genetic material, effectively stopping the infection from spreading. Because aciclovir targets viral enzymes rather than human enzymes, it has relatively few effects on normal body processes. The medicine is eliminated mainly through the kidneys, so dose adjustments may be needed in people with kidney problems.

Is There an Interaction Between Vardenafil and Aciclovir?

No major interaction is commonly reported between vardenafil and aciclovir. These two medicines work through different mechanisms in the body: vardenafil affects blood flow to the penis by inhibiting the PDE5 enzyme, while aciclovir targets viral replication inside infected cells. They are processed differently by the body and do not significantly affect each other's levels or activity.

However, it is essential to declare all medicines you are taking—including aciclovir—during your consultation for vardenafil. Your prescriber or pharmacist will review your full medication list and medical history to check for any individual factors that might affect safety or suitability. Some people taking aciclovir may experience dizziness or headache, which can also be side effects of vardenafil, so your prescriber will consider whether the combination is appropriate for you. Never start, stop, or change any prescribed medicine without professional advice.

What Your Prescriber Checks Before Prescribing Vardenafil and Aciclovir

When you request vardenafil, your prescriber will ask about all your current medicines, including aciclovir, to ensure there are no dangerous interactions. They will also check your medical history, particularly any heart conditions, blood pressure problems, kidney or liver disease, and previous reactions to medicines [5]. Vardenafil must never be taken with nitrates (such as GTN spray or isosorbide mononitrate), nicorandil, riociguat, or recreational drugs called 'poppers', as this combination can cause a dangerous fall in blood pressure.

Your prescriber will also review whether you are taking any medicines that can raise vardenafil levels in the blood, such as potent CYP3A4 inhibitors (including ritonavir, ketoconazole, itraconazole, or clarithromycin). Vardenafil is contraindicated or requires dose adjustment with these medicines [5]. If you are on alpha-blockers for prostate problems or blood pressure (such as tamsulosin or doxazosin), you must be stable on that treatment and start vardenafil at the lowest dose to reduce the risk of dizziness. Aciclovir does not fall into any of these high-risk categories, but your full medication list is always reviewed.

Kidney Function and Medicine Clearance

Both vardenafil and aciclovir are partly eliminated through the kidneys, so if you have kidney problems, your prescriber may need to adjust doses or choose an alternative treatment. Aciclovir doses are often reduced in people with reduced kidney function to prevent side effects. Vardenafil is also used with caution in kidney disease, and the starting dose may be lower. Your prescriber will ask about any kidney conditions and may request recent blood test results if relevant.

Practical Advice for Taking Vardenafil and Aciclovir Together

If you have been prescribed both vardenafil and aciclovir, you can usually take them on the same day without concern, as no major interaction is commonly reported. Take each medicine exactly as directed: aciclovir is typically taken with or without food at regular intervals throughout the day, while vardenafil is taken about 25 to 60 minutes before planned sexual activity [5]. Do not take more than one dose of vardenafil in 24 hours.

Be aware that both medicines can occasionally cause headache or dizziness. If you experience these side effects, avoid driving or operating machinery until you know how the medicines affect you. Drink plenty of water, especially when taking aciclovir, as this helps your kidneys clear the medicine. Limit alcohol when using vardenafil, as heavy drinking can worsen erectile dysfunction and increase the risk of dizziness or low blood pressure. If you develop any new or troubling symptoms, contact your GP or pharmacist for advice.

When to Seek Medical Advice About Vardenafil and Aciclovir

Most people tolerate vardenafil and aciclovir well when taken together, but you should seek urgent medical help if you experience an erection lasting more than four hours (priapism), sudden loss of vision or hearing, or chest pain during sexual activity. These are rare but serious side effects of PDE5 inhibitors that require immediate attention [5]. If you develop severe dizziness, fainting, or an unusually fast or slow heartbeat, contact your GP or call NHS 111 for advice.

If your aciclovir is not controlling your herpes symptoms, or if you develop signs of a severe allergic reaction (such as swelling of the face, lips, or throat, or difficulty breathing), seek medical help immediately. Always inform any healthcare professional treating you that you are taking both vardenafil and aciclovir. If you are prescribed a new medicine by your GP or another doctor, check with your pharmacist whether it is safe to continue vardenafil, as some medicines (particularly potent antifungals, certain HIV medicines, and some antibiotics) can interact with PDE5 inhibitors.

Reporting Side Effects

If you experience any side effects from vardenafil or aciclovir, you can report them via the Yellow Card Scheme at 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. Your pharmacist or GP can also help you report side effects and advise whether you should continue treatment.

Scientific References

1. NHS. (n.d.). Erectile dysfunction (impotence). NHS website. https://www.nhs.uk/conditions/erection-problems-erectile-dysfunction/ [accessed 27 October 2026]
2. Joint Formulary Committee. (n.d.). Vardenafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/vardenafil/ [accessed 27 October 2026]
3. Electronic Medicines Compendium. (n.d.). Summaries of Product Characteristics and Patient Information Leaflets. https://www.medicines.org.uk/emc/ [accessed 27 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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