Vardenafil and Canagliflozin: Can They Be Taken Together?

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Key takeaways

• No major direct interaction is commonly reported between vardenafil and canagliflozin.
• Both medicines can lower blood pressure slightly; stay well hydrated and watch for dizziness.
• Your prescriber will review all your medicines and medical history before prescribing vardenafil.
• Erectile dysfunction is more common in men with diabetes and is treatable alongside diabetes medicines.
• Never take vardenafil with nitrates, nicorandil, riociguat, or poppers—this combination is dangerous.

What Is Vardenafil and How Does It Work?

Vardenafil is a prescription medicine used to treat erectile dysfunction in adult men. It belongs to a group of medicines called PDE5 inhibitors, which also includes sildenafil (Viagra) and tadalafil (Cialis) [5]. Vardenafil works by relaxing the blood vessels in the penis, allowing more blood to flow into the area when you are sexually aroused. This helps you to get and keep an erection suitable for sexual activity.

Vardenafil is available in 5 mg, 10 mg, and 20 mg tablets. The usual starting dose is 10 mg, taken about 25 to 60 minutes before sexual activity, and no more than once a day [5]. It does not work automatically—you still need sexual stimulation for it to be effective. The medicine can help improve erectile function, but it does not cure ED or increase sexual desire.

Like all PDE5 inhibitors, vardenafil can lower blood pressure slightly, which is usually not a problem for most men. However, this effect is important when considering other medicines you take, particularly those that also affect blood pressure or interact with how vardenafil is processed in your body [5].

What Is Canagliflozin and Why Is It Prescribed?

Canagliflozin is a prescription medicine used to treat type 2 diabetes. It belongs to a class of medicines called SGLT2 inhibitors (sodium-glucose co-transporter 2 inhibitors). Canagliflozin works by helping your kidneys remove glucose (sugar) from your bloodstream through your urine, which helps to lower blood sugar levels.

This medicine is usually prescribed alongside diet and exercise to improve blood sugar control in adults with type 2 diabetes. Canagliflozin may also have benefits for your heart and kidneys, which is why it is sometimes chosen for people with diabetes who have additional cardiovascular or kidney concerns. Common brand names include Invokana.

Canagliflozin does not directly affect the blood vessels in the penis or the enzymes that vardenafil targets. However, because it is used to manage diabetes—a condition strongly linked to erectile dysfunction—many men taking canagliflozin may also seek treatment for ED. Understanding how these medicines work together is important for safe and effective treatment [2].

The Link Between Diabetes and Erectile Dysfunction

Erectile dysfunction is significantly more common in men with diabetes than in the general population [10]. High blood sugar levels over time can damage blood vessels and nerves, including those needed for erections. Managing your diabetes well with medicines like canagliflozin, along with lifestyle changes, can help reduce the risk of ED worsening. Many men with diabetes benefit from ED treatments such as vardenafil, which can be used safely alongside diabetes medicines when prescribed appropriately [2].

At a glance

Do Vardenafil and Canagliflozin Interact With Each Other?

No major direct interaction between vardenafil and canagliflozin is commonly reported. These two medicines work through different mechanisms in the body: vardenafil affects an enzyme (PDE5) in the blood vessels of the penis, while canagliflozin affects glucose transporters in the kidneys. They are not known to interfere with each other's effectiveness or significantly increase the risk of side effects when used together.

However, it is important to remember that both medicines can have effects on your cardiovascular system. Canagliflozin can sometimes cause a small drop in blood pressure, particularly when you first start taking it or if you become dehydrated. Vardenafil also lowers blood pressure slightly as part of how it works [5]. When taken together, there is a theoretical possibility of an additive blood-pressure-lowering effect, which could lead to dizziness or light-headedness in some men.

Your prescriber will assess your overall cardiovascular health, blood pressure, and any other medicines you take before prescribing vardenafil. If you are stable on canagliflozin and your blood pressure is well controlled, vardenafil is usually considered safe to use. You should always declare all your current medicines, including canagliflozin, during your consultation so that your prescriber can make an informed decision [2][5].

What Does Your Prescriber Check Before Prescribing Vardenafil and Canagliflozin Together?

Before prescribing vardenafil to someone taking canagliflozin, your prescriber will review your full medical history and current medications. They will check your cardiovascular health, including any history of heart disease, stroke, or blood pressure problems. Because both medicines can affect blood pressure, it is important to ensure your blood pressure is stable and that you are not at increased risk of dizziness or fainting.

Your prescriber will also ask about any other medicines you take, particularly those that can interact with vardenafil. These include nitrates (such as GTN spray or isosorbide mononitrate), nicorandil, riociguat, alpha-blockers (such as tamsulosin or doxazosin), and medicines that affect how vardenafil is broken down in the liver (such as certain antifungals or antibiotics) [5]. If you take any of these, vardenafil may not be suitable, or your dose may need to be adjusted.

Your prescriber will also consider your diabetes control and any complications you may have, such as kidney disease or neuropathy (nerve damage). If you have severe kidney or liver problems, vardenafil may need to be used with caution or at a lower dose. The prescriber will ensure that the benefits of treatment outweigh any potential risks in your individual situation [2][5].

Declaring All Your Medicines

It is essential to tell your prescriber about every medicine you take, including prescription medicines, over-the-counter products, herbal remedies, and supplements. Even if you think a medicine is unrelated to ED or diabetes, it could still interact with vardenafil. For example, St John's wort (a herbal remedy for low mood) can make vardenafil less effective, and some antibiotics or antifungals can increase vardenafil levels in your blood [5]. Being open and thorough during your consultation helps your prescriber keep you safe.

Practical Advice for Taking Vardenafil With Canagliflozin

If your prescriber has approved vardenafil for you while you are taking canagliflozin, there are some practical steps you can take to use both medicines safely and effectively. First, take each medicine exactly as prescribed. Do not change the dose or timing of either medicine without speaking to your prescriber or pharmacist first.

Because canagliflozin can increase the risk of dehydration (especially in hot weather or if you are unwell), make sure you drink plenty of fluids. Dehydration can lower your blood pressure further and may increase the chance of dizziness when you take vardenafil. If you feel light-headed or dizzy after taking vardenafil, sit or lie down until the feeling passes, and avoid driving or operating machinery.

Take vardenafil about 25 to 60 minutes before you plan to have sex, and remember that it only works when you are sexually aroused [5]. Avoid drinking large amounts of alcohol, as this can make erectile dysfunction worse and add to the blood-pressure-lowering effects of vardenafil. Grapefruit juice can also increase vardenafil levels in your blood, so it is best to avoid it. If you experience any unusual symptoms, such as chest pain, a prolonged erection lasting more than four hours, or sudden vision or hearing loss, seek urgent medical help.

Other Medicines and Conditions to Be Aware Of

While vardenafil and canagliflozin do not interact directly, vardenafil does have important interactions with other medicines that you must be aware of. Never take vardenafil if you are using nitrates (such as GTN spray, isosorbide mononitrate, or isosorbide dinitrate), nicorandil, riociguat, or recreational drugs known as 'poppers' (amyl or alkyl nitrites). Combining vardenafil with any of these can cause a dangerous drop in blood pressure [5].

If you take alpha-blockers for an enlarged prostate (such as tamsulosin, doxazosin, or alfuzosin), there is also a risk of low blood pressure and dizziness. Your prescriber will usually start you on the lowest dose of vardenafil and ensure you are stable on your alpha-blocker before prescribing ED treatment [5]. Some medicines that affect liver enzymes, such as ritonavir, ketoconazole, itraconazole, or clarithromycin, can increase vardenafil levels and may mean vardenafil is not suitable for you.

If you take any blood-pressure medicines in addition to canagliflozin, your prescriber will consider the combined effect on your blood pressure. Most men can use vardenafil safely with well-controlled blood pressure, but it is important to declare all your medicines during your consultation. Do not stop or change any prescribed medicine without advice from your doctor or pharmacist [2][5].

When Vardenafil Is Not Suitable

Vardenafil is not suitable for everyone. It should not be used if sexual activity is inadvisable for you, for example if you have had a recent heart attack or stroke, unstable angina, severe heart failure, or very low blood pressure. It is also not suitable if you have a history of non-arteritic anterior ischaemic optic neuropathy (NAION), a rare condition causing sudden vision loss, or certain inherited eye conditions affecting the retina [5]. Your prescriber will assess your suitability during your consultation.

When to get urgent help

• An erection lasting more than 4 hours (priapism)—go to A&E immediately.
• Sudden loss of vision or hearing—stop taking vardenafil and seek urgent medical help.
• Chest pain during or after sex—stop sexual activity and call 999 if the pain does not go away quickly.
• Severe dizziness, fainting, or a very fast or irregular heartbeat—seek same-day medical advice.
• Signs of a severe allergic reaction (swelling of the 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.