Vardenafil and Valaciclovir: Can You Take Them Together?
Learn about the interaction between these medicines and how our UK pharmacist-led consultation ensures your safety.
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Vardenafil and Valaciclovir: Understanding the Interaction
Published: 5 November 2026
Many men wonder whether vardenafil and valaciclovir can be taken together safely. Vardenafil (generic Levitra) is a prescription medicine for erectile dysfunction, whilst valaciclovir is an antiviral used to treat herpes infections and shingles. The good news is that no major interaction is commonly reported between these two medicines, but your prescriber will still check your full medication list during your consultation to ensure the combination is suitable for you.
Key takeaways
- No major interaction is commonly reported between vardenafil and valaciclovir
- Always declare all medicines during your consultation so your prescriber can check safety
- Never take vardenafil with nitrates, nicorandil, riociguat, poppers, or another PDE5 inhibitor
- Vardenafil is taken 25–60 minutes before sex and requires sexual stimulation to work
- Seek urgent help if you have chest pain, an erection over 4 hours, or sudden vision loss
What Is Vardenafil and How Does It Work?
Vardenafil is a phosphodiesterase type 5 (PDE5) inhibitor licensed in the UK for the treatment of erectile dysfunction in adult men [5]. It works by relaxing the blood vessels in the penis, allowing increased blood flow when you are sexually aroused. Vardenafil is the active ingredient in branded Levitra and is available in 5mg, 10mg, and 20mg tablets.
You typically take vardenafil about 25 to 60 minutes before sexual activity, and it requires sexual stimulation to work [5]. The medicine does not cause an automatic erection; it simply helps your body respond naturally when you are aroused. Vardenafil should not be taken more than once a day, and it is only available on prescription after a consultation with a UK-registered prescriber who will check your medical history and current medicines.
What Is Valaciclovir and What Is It Used For?
Valaciclovir is an antiviral medicine used to treat infections caused by herpes viruses, including genital herpes, cold sores, and shingles (herpes zoster). It works by stopping the virus from multiplying, which helps to reduce the severity and duration of outbreaks. Valaciclovir is converted in the body to aciclovir, the active antiviral compound.
The medicine is taken by mouth, usually two to three times a day depending on the condition being treated. It is most effective when started as soon as symptoms appear. Valaciclovir does not cure herpes infections but helps manage symptoms and reduce the frequency of recurrent episodes. It is a prescription-only medicine in the UK.
How Valaciclovir Affects the Body
Valaciclovir is processed mainly by the kidneys and does not significantly affect the liver enzymes that break down many other medicines. This means it has a low potential for drug interactions compared with some other antiviral medicines. However, it is still important to tell your prescriber about all medicines you take, including over-the-counter products and supplements, so they can check for any possible interactions or dose adjustments needed.
At a glance
Can You Take Vardenafil and Valaciclovir Together?
No major interaction is commonly reported between vardenafil and valaciclovir. These medicines work in different ways and are processed by the body through different pathways, so they are not expected to interfere with each other significantly. However, every patient is different, and your prescriber will review your full medical history and all current medicines during your consultation to ensure the combination is safe for you.
It is important to declare all medicines you are taking, including valaciclovir, when you request vardenafil. Your prescriber will check for any individual factors—such as kidney function, other health conditions, or additional medicines—that might affect how these treatments work together. Never assume a combination is safe without professional advice, even if no major interaction is widely known.
What Your Prescriber Will Check
During your online consultation, the prescriber will ask about your current medicines, including the dose and frequency of valaciclovir. They will also check your kidney function, as both medicines are partly eliminated by the kidneys. If you have reduced kidney function, dose adjustments may be needed for either medicine. The prescriber will also review any other health conditions, such as heart problems or low blood pressure, that could affect the safety of vardenafil.
Important Safety Checks When Taking Vardenafil
Vardenafil must never be taken with certain medicines that can cause a dangerous drop in blood pressure. These include nitrates (such as GTN spray, isosorbide mononitrate, or isosorbide dinitrate), nicorandil, riociguat, and recreational drugs known as 'poppers' (amyl or alkyl nitrites) [5]. Do not take vardenafil with another PDE5 inhibitor, such as sildenafil or tadalafil, as this increases the risk of side effects.
If you take alpha-blockers for prostate problems or high blood pressure (such as doxazosin, tamsulosin, or alfuzosin), tell your prescriber. These medicines can interact with vardenafil, causing dizziness or fainting due to low blood pressure. You should be stable on your alpha-blocker before starting vardenafil, and your prescriber may recommend a lower starting dose [5].
Potent CYP3A4 inhibitors—medicines that slow the breakdown of vardenafil—can raise its levels in the blood. Examples include ritonavir, cobicistat, ketoconazole, itraconazole, and clarithromycin. Vardenafil is contraindicated or should be avoided with these medicines; your prescriber will check the Summary of Product Characteristics if you take any of these treatments [5].
Declare All Your Medicines
Always tell your prescriber about every medicine you take, including valaciclovir, over-the-counter products, and supplements. This helps ensure vardenafil is safe and effective for you.
Practical Advice for Taking Vardenafil and Valaciclovir
If your prescriber confirms that vardenafil and valaciclovir are suitable for you, take each medicine exactly as directed. Vardenafil is usually taken about 25 to 60 minutes before sexual activity, on an empty stomach or after a light meal, as a heavy or high-fat meal can delay its effect [5]. Valaciclovir is typically taken with or without food, according to the instructions for your specific condition.
Avoid drinking large amounts of alcohol when taking vardenafil, as alcohol can worsen erectile dysfunction and increase the risk of dizziness or low blood pressure. Grapefruit juice can raise vardenafil levels and should be avoided. Stay well hydrated, especially when taking valaciclovir, as this helps your kidneys process the medicine effectively.
If you experience any unusual symptoms—such as severe dizziness, chest pain during sex, an erection lasting more than four hours, or sudden changes in vision or hearing—stop taking vardenafil and seek urgent medical help. Always keep your prescriber informed of any new medicines or changes to your health, and do not stop or change a prescribed medicine without advice.
When to Seek Medical Advice
Contact your GP or pharmacist if you develop side effects from either medicine, such as headache, flushing, indigestion, or nausea. Most side effects are mild and temporary, but if they persist or become troublesome, your prescriber may adjust your dose or suggest an alternative treatment. If you have new or worsening erectile dysfunction, see your GP, as ED can be an early sign of heart disease or diabetes [1].
How Cured Pharmacy Can Help with Vardenafil and Valaciclovir
Cured Pharmacy is a GPhC-registered online pharmacy (GPhC 9012511) offering a convenient, confidential service for erectile dysfunction treatments. When you request vardenafil through our website, you will complete a detailed online consultation that asks about all your current medicines, including valaciclovir, and any health conditions. A UK-registered prescriber will review your answers and check that vardenafil is safe and suitable for you.
If approved, your medicine is dispensed by our UK pharmacy and delivered discreetly to your door. We stock a range of ED treatments, including vardenafil (generic Levitra) at £16.95 for your first order (£13.56 with code Ednew), as well as sildenafil, tadalafil, and avanafil. Our team is here to answer any questions about your treatment, and you can contact us at any time for advice.
We encourage you to be open and honest in your consultation. Declaring all your medicines, including valaciclovir, helps our prescribers make the safest decision for you. If you have any concerns about taking vardenafil and valaciclovir together, our pharmacists are available to discuss your individual situation and provide tailored advice.
When to get urgent help
- Erection lasting more than 4 hours (priapism) – go to A&E immediately
- Sudden loss of vision or hearing – stop vardenafil and seek urgent medical help
- Chest pain during or after sex – call 999 and do not take more vardenafil
- Severe dizziness or fainting – stop vardenafil and contact your GP or call 111
- Allergic reaction (swelling of face, lips, or throat, difficulty breathing) – call 999
Call 999 or go to A&E in an emergency, or contact NHS 111 for urgent advice.
Scientific References
- NHS. (n.d.). Erectile dysfunction (impotence). NHS website. https://www.nhs.uk/conditions/erection-problems-erectile-dysfunction/ [accessed 5 November 2026]
- Joint Formulary Committee. (n.d.). Vardenafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/vardenafil/ [accessed 5 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.
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Your Questions Answered
Can't find your answer? Our UK pharmacists review every consultation and can help.
Is it safe to take vardenafil and valaciclovir at the same time?
No major interaction is commonly reported between vardenafil and valaciclovir. However, your prescriber will check your full medication list and medical history during your consultation to ensure the combination is safe for you.
Do I need to tell my prescriber I'm taking valaciclovir?
Yes, always declare all medicines you are taking, including valaciclovir, when you request vardenafil. This helps your prescriber check for any possible interactions or dose adjustments needed.
Can valaciclovir affect how vardenafil works?
Valaciclovir is not expected to affect how vardenafil works, as the two medicines are processed by the body in different ways. Your prescriber will confirm this is the case for your individual situation.
What medicines should I never take with vardenafil?
Do not take vardenafil with nitrates, nicorandil, riociguat, poppers, or another PDE5 inhibitor, as this can cause a dangerous drop in blood pressure. Always tell your prescriber about all your medicines.
Can I drink alcohol while taking vardenafil and valaciclovir?
Avoid large amounts of alcohol when taking vardenafil, as it can worsen erectile dysfunction and increase the risk of dizziness or low blood pressure. Moderate alcohol is unlikely to interact with valaciclovir.
How long before sex should I take vardenafil?
Take vardenafil about 25 to 60 minutes before sexual activity. It requires sexual stimulation to work and should not be taken more than once a day.
What should I do if I get side effects from vardenafil?
Contact your GP or pharmacist if you experience side effects such as headache, flushing, or indigestion. Seek urgent help if you have chest pain, an erection lasting more than four hours, or sudden vision or hearing loss.
Can I get vardenafil from Cured Pharmacy if I take valaciclovir?
Yes, if your online consultation shows that vardenafil is safe and suitable for you. A UK-registered prescriber will review your answers, including all current medicines, before approving your treatment.
Medically reviewed by
Tarun Kumar, Superintendent Pharmacist (GPhC 2233073)