Vardenafil and Atazanavir: Can They Be Taken Together?

Takes less than 2 minutes to complete 100% online

Choose your treatment

Select from our recommended UK-licensed medications.

Answer quick questions

Select safe UK treatments. Quick answers.

Get it delivered fast

We will deliver direct to you as quickly as tomorrow.

Vardenafil and Atazanavir: Understanding the Interaction

Published: 27 October 2026

Vardenafil and atazanavir should not be taken together because atazanavir significantly increases vardenafil levels in the blood, raising the risk of serious side effects including dangerously low blood pressure. Atazanavir is a protease inhibitor used to treat HIV, and it strongly blocks the enzyme (CYP3A4) that breaks down vardenafil, an erectile dysfunction medicine. If you are taking atazanavir or another boosted HIV medicine and need treatment for erectile dysfunction, your prescriber will recommend a safer alternative and adjust the dose to protect your health.

What is vardenafil and atazanavir used for?

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 to help achieve and maintain an erection when sexually aroused [5]. Vardenafil is usually taken about 25 to 60 minutes before sexual activity, and its effects can last for several hours. Common doses are 5mg, 10mg, or 20mg, depending on individual response and tolerability.

Atazanavir is an antiretroviral medicine used to treat HIV infection. It is a protease inhibitor that stops the virus from multiplying in the body, helping to control HIV and protect the immune system. Atazanavir is often prescribed alongside ritonavir or cobicistat, which are 'boosting' agents that increase atazanavir levels and make it more effective. Because atazanavir (especially when boosted) is a very potent inhibitor of the liver enzyme CYP3A4, it can dramatically increase the blood levels of many other medicines, including vardenafil, leading to potentially serious interactions.

How do vardenafil and atazanavir interact?

The interaction between vardenafil and atazanavir occurs because atazanavir blocks CYP3A4, the main enzyme responsible for breaking down vardenafil in the liver [5]. When this enzyme is inhibited, vardenafil stays in the bloodstream much longer and at much higher concentrations than intended. This can lead to an excessive and prolonged effect, significantly increasing the risk of side effects such as severe headaches, dizziness, flushing, visual disturbances, and—most seriously—a dangerous drop in blood pressure.

Atazanavir boosted with ritonavir or cobicistat is classified as a potent CYP3A4 inhibitor, and the British National Formulary advises that vardenafil should be avoided in patients taking such medicines [5]. Even unboosted atazanavir can raise vardenafil levels, though the effect is less pronounced. Because the increase in vardenafil exposure can be several-fold, dose adjustments alone may not be sufficient to ensure safety, which is why the combination is generally contraindicated or strongly discouraged.

Why this interaction matters

The consequences of this interaction are not trivial. Excessive vardenafil levels can cause prolonged low blood pressure, which may lead to fainting, falls, or cardiovascular complications, particularly in men with underlying heart conditions. There is also a risk of priapism (a painful erection lasting more than four hours), which requires emergency treatment to prevent permanent damage. For these reasons, prescribers take great care to review all current medicines, including HIV treatments, before recommending any erectile dysfunction therapy.

What your prescriber checks before recommending treatment

Before prescribing any erectile dysfunction medicine, a UK prescriber will ask detailed questions about all the medicines you currently take, including prescription drugs, over-the-counter products, and herbal supplements. If you are taking atazanavir or any other protease inhibitor, this will be flagged immediately because of the known interaction with vardenafil and the need for careful alternative selection [2].

Your prescriber will also review your cardiovascular health, blood pressure, and any history of heart disease, stroke, or liver problems. They will check whether you are taking nitrates, alpha-blockers, or other medicines that can interact with PDE5 inhibitors. This comprehensive review ensures that the chosen treatment is both effective and safe for your individual circumstances.

If vardenafil is not suitable because of your HIV medication, your prescriber will discuss alternative erectile dysfunction treatments that have a lower risk of interaction, such as sildenafil or tadalafil at reduced doses, or non-oral options. The goal is to find a solution that works for you without compromising your HIV treatment or putting your health at risk.

Safer alternatives to vardenafil when taking atazanavir

If you are taking atazanavir and need treatment for erectile dysfunction, your prescriber may recommend sildenafil or tadalafil instead of vardenafil, but at carefully adjusted doses. Sildenafil (generic Viagra) is also affected by CYP3A4 inhibitors, but the interaction is more predictable and manageable with dose reduction [3]. For men on potent inhibitors like boosted atazanavir, the starting dose of sildenafil is typically reduced to 25mg, with a maximum of 25mg in 48 hours.

Tadalafil (generic Cialis) is another option, though it too is metabolised by CYP3A4. When taken on-demand, the dose may be limited to 10mg with no more than one dose in 72 hours if you are on a potent CYP3A4 inhibitor [4]. Daily tadalafil is generally not recommended in this situation. Avanafil (Spedra) is also affected by strong CYP3A4 inhibitors and is usually avoided or used with caution and dose adjustment [6].

Your prescriber will weigh the benefits and risks of each option based on your full medication list, your health status, and your preferences. It is essential never to take vardenafil alongside atazanavir without explicit guidance from a healthcare professional, and never to obtain erectile dysfunction medicines from unregulated sources, as this bypasses vital safety checks.

Non-oral treatments

If oral PDE5 inhibitors are not suitable or effective, other prescription options include Vitaros (alprostadil cream applied to the tip of the penis) or Caverject (alprostadil injection into the penis) [7]. These treatments work locally rather than systemically, so they are not affected by CYP3A4 inhibitors. A vacuum erection device is another non-drug option. Your GP or a specialist can discuss these alternatives if needed.

Practical advice if you are taking both medicines

If you have been prescribed vardenafil and are also taking atazanavir, contact your prescriber or pharmacist immediately before taking any doses. Do not assume that because both medicines were prescribed by different doctors, they are safe to take together. Drug interactions can occur even when treatments are prescribed separately, which is why it is vital to keep all your healthcare providers informed about every medicine you take.

Never adjust the dose of vardenafil yourself in an attempt to reduce the interaction risk. Splitting tablets or taking smaller amounts without professional guidance does not eliminate the danger and may still result in harmful effects. Similarly, do not stop or change your HIV medication without consulting your HIV specialist, as this could compromise your viral suppression and overall health.

If you experience any unusual symptoms after taking vardenafil—such as severe dizziness, fainting, chest pain, prolonged erection, sudden vision or hearing loss—seek urgent medical help. Always carry an up-to-date list of your medicines (including doses and frequencies) and share it with any healthcare professional you see, including pharmacists, dentists, and emergency staff.

How Cured Pharmacy can help with vardenafil and atazanavir concerns

At Cured Pharmacy, every request for erectile dysfunction treatment begins with a thorough online consultation reviewed by a UK-registered prescriber. You will be asked to list all your current medicines, including HIV treatments, so that any potential interactions—such as vardenafil and atazanavir—can be identified and managed safely. Our prescribers follow the latest UK guidelines and will recommend an appropriate alternative if vardenafil is not suitable for you [2][5].

We stock a range of erectile dysfunction treatments, including sildenafil, tadalafil, and avanafil, which may be prescribed at adjusted doses if you are taking medicines that affect CYP3A4. Our service is discreet, convenient, and designed to give you access to safe, effective treatment without compromising your other health needs. All medicines are dispensed by our GPhC-registered pharmacy and delivered in plain, unmarked packaging.

If you have questions about drug interactions, side effects, or which treatment might be right for you, our pharmacist-led team is here to help. We encourage you to be open and honest in your consultation, as this ensures you receive the safest and most effective care. Remember, erectile dysfunction can be an early warning sign of cardiovascular disease or diabetes, so if this is a new problem, we also recommend seeing your GP for a full health check [1].

Starting your consultation

To begin, simply select the erectile dysfunction treatment you are interested in and complete the online questionnaire. Be sure to include atazanavir and any other HIV medicines in the list of current medications. A UK prescriber will review your answers, and if a prescription is appropriate, your treatment will be dispensed and dispatched quickly. If vardenafil is not suitable, the prescriber will suggest a safer alternative and explain why.

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. National Institute for Health and Care Excellence. (n.d.). Erectile dysfunction. Clinical Knowledge Summaries. https://cks.nice.org.uk/topics/erectile-dysfunction/ [accessed 27 October 2026]
3. Joint Formulary Committee. (n.d.). Sildenafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/sildenafil/ [accessed 27 October 2026]
4. Joint Formulary Committee. (n.d.). Tadalafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/tadalafil/ [accessed 27 October 2026]
5. Joint Formulary Committee. (n.d.). Vardenafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/vardenafil/ [accessed 27 October 2026]
6. Joint Formulary Committee. (n.d.). Avanafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/avanafil/ [accessed 27 October 2026]
7. Joint Formulary Committee. (n.d.). Alprostadil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/alprostadil/ [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.