Vardenafil and Azithromycin: Can They Be Taken Together?

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What Is Vardenafil and How Does It Work?

Vardenafil is a phosphodiesterase type 5 (PDE5) inhibitor licensed in the UK to treat erectile dysfunction (ED) [5]. It works by relaxing blood vessels in the penis, allowing increased blood flow when you are sexually aroused. Vardenafil does not cause an erection on its own—sexual stimulation is still needed [5].

The medicine is typically taken about 25 to 60 minutes before sexual activity, and its effects can last for several hours [5]. Common doses are 5 mg, 10 mg, or 20 mg, depending on your response and tolerability. Vardenafil should not be taken more than once a day.

Like all PDE5 inhibitors, vardenafil is only available on prescription in the UK after a consultation with a qualified healthcare professional. At Cured Pharmacy, a UK-registered prescriber reviews your medical history and current medicines during an online consultation to ensure vardenafil is safe and suitable for you.

What Is Azithromycin and When Is It Prescribed?

Azithromycin is a macrolide antibiotic used to treat a range of bacterial infections [12]. It is commonly prescribed for respiratory tract infections (such as pneumonia and bronchitis), skin and soft tissue infections, and certain sexually transmitted infections including chlamydia and non-specific urethritis.

Azithromycin is usually taken as a short course—often a single dose or a three-day course—depending on the infection being treated. It works by stopping bacteria from growing and multiplying, allowing your immune system to clear the infection.

Because azithromycin is an antibiotic, it should only be used when prescribed by a doctor or other qualified prescriber. It is important to complete the full course as directed, even if you start to feel better, to ensure the infection is fully treated and to reduce the risk of antibiotic resistance.

When to get urgent help

• Fast, irregular, or pounding heartbeat, especially with dizziness or fainting
• Chest pain or discomfort during or after sexual activity
• An erection lasting more than 4 hours (priapism)
• Sudden loss of vision in one or both eyes
• Sudden decrease or loss of hearing, possibly with ringing in the ears

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

How Do Vardenafil and Azithromycin Interact?

The interaction between vardenafil and azithromycin relates to the way both medicines can affect the electrical activity of the heart, specifically something called the QT interval [5][12]. Both vardenafil and azithromycin have the potential to prolong the QT interval, which in rare cases can lead to a serious heart rhythm disturbance.

When two medicines that both affect the QT interval are taken together, the risk of this heart rhythm problem may be increased. This does not mean the combination is always unsafe, but it does mean that your prescriber must carefully assess your individual risk before prescribing both medicines together.

Your prescriber will consider factors such as your heart health, other medicines you take, and any conditions that might increase your risk (such as low potassium or magnesium levels, or a personal or family history of heart rhythm problems). In many cases, the combination can be used safely with appropriate monitoring, but the decision must be made by a qualified healthcare professional.

What Happens in Your Body?

The QT interval is a measurement on an electrocardiogram (ECG) that reflects the time it takes for the heart's electrical system to recharge between beats. When this interval becomes too long (QT prolongation), it can occasionally trigger an abnormal heart rhythm called torsades de pointes, which can be life-threatening if not treated promptly.

Both vardenafil and azithromycin can, in susceptible individuals, slightly delay this recharging process. When used together, the effect may be additive. However, serious problems are rare, and most people tolerate the combination well when their prescriber has assessed the risks and deemed it appropriate.

What Your Prescriber Checks Before Combining Vardenafil and Azithromycin

Before prescribing vardenafil alongside azithromycin, your prescriber will ask detailed questions about your medical history and current health. They will want to know about any heart conditions, particularly irregular heartbeats, a history of fainting, or a family history of sudden cardiac death.

You will be asked to list all medicines you currently take, including over-the-counter products and supplements, because other medicines can also affect the QT interval or interact with vardenafil or azithromycin. Examples include certain antidepressants, antipsychotics, and other antibiotics.

Your prescriber may also consider whether you have conditions that affect your electrolyte levels (such as kidney disease, severe diarrhoea or vomiting), as low potassium or magnesium can increase the risk of QT prolongation. In some cases, they may recommend blood tests or an ECG before starting treatment, or they may choose an alternative medicine with a lower risk of interaction.

Declaring All Your Medicines

It is essential to tell your prescriber about every medicine you take, even if you think it is unrelated. This includes prescription medicines, pharmacy medicines, herbal remedies (such as St John's wort), and recreational substances. Some medicines that seem unrelated can still affect how vardenafil or azithromycin work, or increase the risk of side effects.

Never stop or change a prescribed medicine without speaking to your doctor or pharmacist first. If you are prescribed azithromycin by one healthcare provider and vardenafil by another, make sure both are aware of all your medicines so they can coordinate your care safely.

At a glance

Practical Advice for Taking Vardenafil and Azithromycin Together

If your prescriber has assessed the risks and decided that you can take vardenafil and azithromycin together, follow their instructions carefully. Take each medicine exactly as prescribed, at the dose and frequency advised. Do not take more vardenafil than recommended, even if you feel the effect is not strong enough—speak to your prescriber instead.

Be aware of warning signs that might suggest a heart rhythm problem, such as a fast or irregular heartbeat, dizziness, fainting, or chest discomfort. If you experience any of these symptoms, stop taking both medicines and seek urgent medical advice. These symptoms are rare, but it is important to know what to watch for.

Avoid drinking large amounts of alcohol while taking vardenafil, as alcohol can worsen erectile dysfunction and add to the blood-pressure-lowering effect of the medicine, increasing the risk of dizziness [5]. Grapefruit juice can raise vardenafil levels in the blood and should be avoided. Complete the full course of azithromycin as prescribed, even if your symptoms improve, to ensure the infection is fully treated.

When Vardenafil Should Not Be Taken

There are some situations where vardenafil must not be used, regardless of whether you are taking azithromycin. Do not take vardenafil if you are using nitrate medicines for chest pain (such as glyceryl trinitrate spray, isosorbide mononitrate, or isosorbide dinitrate), nicorandil, riociguat, or recreational drugs known as 'poppers' (amyl or alkyl nitrites) [5]. The combination can cause a dangerous drop in blood pressure.

Do not take vardenafil together with another PDE5 inhibitor (such as sildenafil, tadalafil, or avanafil). Vardenafil is also not suitable if you have severe liver or kidney disease, very low blood pressure, a recent heart attack or stroke, unstable angina, severe heart failure, or a history of sudden vision loss (non-arteritic anterior ischaemic optic neuropathy, or NAION) [5].

If you have any of these conditions or take any of these medicines, tell your prescriber during your consultation. They will recommend a safer alternative or address the underlying condition before considering ED treatment. At Cured Pharmacy, every prescription is reviewed by a UK-registered prescriber to ensure your safety.

Other Medicines That Interact with Vardenafil

Vardenafil is broken down in the body by an enzyme called CYP3A4. Medicines that strongly inhibit this enzyme (such as ritonavir, cobicistat, ketoconazole, itraconazole, and clarithromycin) can raise vardenafil levels significantly, increasing the risk of side effects [5]. Vardenafil is generally avoided or contraindicated with these potent inhibitors—your prescriber will check the specific guidance.

Alpha-blockers (such as doxazosin, tamsulosin, or alfuzosin) used for prostate symptoms or high blood pressure can also interact with vardenafil, causing dizziness or a drop in blood pressure. If you take an alpha-blocker, your prescriber will ensure you are stable on that medicine and may start you on a lower dose of vardenafil [5].

In summary

• Vardenafil and azithromycin can sometimes be taken together if your prescriber assesses the risks first
• Both medicines can affect heart rhythm, so your heart health and other medicines must be reviewed
• Watch for dizziness, fainting, or irregular heartbeat and seek urgent help if these occur
• Always declare all medicines during your consultation, including antibiotics and over-the-counter products
• Do not take vardenafil with nitrates, nicorandil, riociguat, poppers, or another PDE5 inhibitor

Frequently Asked Questions