Can You Take Tadalafil and Irbesartan Together?

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Tadalafil and Irbesartan: Understanding the Interaction

Published: 22 October 2026

Many men wonder whether tadalafil and irbesartan can be taken together safely. The good news is that tadalafil, a medicine used to treat erectile dysfunction, can usually be prescribed alongside irbesartan, a blood pressure medicine, but your prescriber will need to check your blood pressure is stable and adjust doses if necessary [1][2]. Because both medicines can lower blood pressure, there is a risk of dizziness or light-headedness, especially when standing up, so careful monitoring is essential.

What Is Tadalafil and How Does It Work?

Tadalafil is a prescription medicine used to treat erectile dysfunction (ED). It belongs to a group of medicines called PDE5 inhibitors, which work by relaxing blood vessels in the penis, allowing more blood to flow in when you are sexually aroused [4]. Tadalafil is the active ingredient in branded Cialis and is also available as a generic medicine at lower cost.

Tadalafil comes in two forms: on-demand tablets (usually 10 mg or 20 mg) taken at least 30 minutes before sexual activity, with effects lasting up to 36 hours, and daily tablets (2.5 mg or 5 mg) taken once a day regardless of when you plan to have sex [4]. Both types require sexual stimulation to work—they do not cause an automatic erection.

At Cured Pharmacy, tadalafil is available from £7.95 after an online consultation with a UK prescriber. The consultation ensures the medicine is safe and suitable for you, especially if you take other medicines like irbesartan.

What Is Irbesartan and Why Is It Prescribed?

Irbesartan is a medicine used to treat high blood pressure (hypertension) and to protect the kidneys in people with type 2 diabetes. It belongs to a class of medicines called angiotensin II receptor blockers (ARBs), which work by blocking the action of a hormone that narrows blood vessels, allowing blood to flow more easily and reducing blood pressure.

High blood pressure often has no symptoms but increases the risk of heart attack, stroke, and kidney problems. Irbesartan is usually taken once a day, and it may take several weeks to see the full benefit. It is important to keep taking irbesartan even if you feel well, as high blood pressure can damage your body silently over time.

Many men with high blood pressure also experience erectile dysfunction, partly because the same factors that damage blood vessels in the heart can affect blood flow to the penis [10]. Treating high blood pressure is essential for long-term health, and in many cases ED treatment can be safely added once blood pressure is controlled.

The Link Between Blood Pressure and Erectile Dysfunction

Erectile dysfunction is more common in men with high blood pressure, diabetes, and heart disease [1][10]. These conditions damage the lining of blood vessels, making it harder for blood to flow into the penis. In fact, ED can be an early warning sign of cardiovascular disease, which is why it is important to see your GP if you develop new erection problems—they may want to check your heart health and blood pressure.

How Do Tadalafil and Irbesartan Interact?

Tadalafil and irbesartan can be taken together, but both medicines have the potential to lower blood pressure. Irbesartan lowers blood pressure by relaxing and widening blood vessels throughout the body. Tadalafil also causes blood vessels to relax, mainly in the penis, but it can have a mild blood-pressure-lowering effect elsewhere [4].

When taken together, the combined effect on blood pressure is usually small, but some men may experience dizziness, light-headedness, or even fainting, especially when standing up quickly. This is more likely if your blood pressure is already on the lower side, if you are dehydrated, or if you drink alcohol [2][4].

This interaction is not a reason to avoid tadalafil if you take irbesartan, but it does mean your prescriber will check your blood pressure is stable and may start you on a lower dose of tadalafil. You should not stop or change your irbesartan dose without speaking to your doctor, as uncontrolled high blood pressure is far more dangerous than the small risk of dizziness from the combination.

Why the Interaction Happens (In Plain English)

Both tadalafil and irbesartan work by relaxing the smooth muscle in blood vessel walls. Irbesartan blocks a hormone that normally tightens blood vessels, while tadalafil blocks an enzyme (PDE5) that would otherwise break down a substance that keeps blood vessels relaxed. When you take both medicines, the relaxing effects can add up, leading to a slightly greater drop in blood pressure than either medicine alone. For most men, this is not a problem, but it is why your prescriber needs to know about all your medicines before prescribing tadalafil.

What Your Prescriber Will Check Before Prescribing Tadalafil and Irbesartan

Before prescribing tadalafil, your prescriber will ask about your current medicines, including irbesartan, and check whether your blood pressure is stable and well controlled. They will also ask about any history of heart disease, stroke, or other cardiovascular conditions, as these affect whether ED treatment is safe for you [1][2].

If you are already taking irbesartan and your blood pressure is stable, tadalafil can usually be prescribed, often starting with a lower dose (such as 10 mg on-demand or 2.5 mg daily) to minimise the risk of dizziness [4]. Your prescriber may also advise you to monitor how you feel after taking the first dose, especially if you notice any light-headedness.

You should tell your prescriber about any other blood-pressure medicines you take, as well as medicines for heart disease, diabetes, or prostate problems (such as alpha-blockers like tamsulosin), because these can also interact with tadalafil. Never take tadalafil if you use nitrate medicines (such as GTN spray or isosorbide mononitrate) or nicorandil, as the combination can cause a dangerous drop in blood pressure [4].

Practical Advice for Taking Tadalafil and Irbesartan Together

If you are prescribed tadalafil while taking irbesartan, take both medicines exactly as directed. Continue taking your irbesartan at the same time each day, and take tadalafil as advised—either on-demand before sexual activity or once daily, depending on the dose prescribed [4].

To reduce the risk of dizziness, stand up slowly from sitting or lying down, especially after taking tadalafil for the first time. Avoid drinking large amounts of alcohol, as this can make dizziness worse and may also make it harder to get an erection. Stay well hydrated, but do not suddenly increase your fluid intake without medical advice if you have heart or kidney problems.

If you feel dizzy, light-headed, or faint after taking tadalafil, sit or lie down until the feeling passes. If symptoms are severe or do not improve, contact your GP or call NHS 111 for advice. Do not drive or operate machinery if you feel dizzy. Most men tolerate the combination well, but it is important to be aware of how you feel, especially during the first few doses.

When to Seek Medical Advice

Seek urgent medical help if you experience chest pain during or after sex, as this could be a sign of a heart problem. Also seek immediate help if you have an erection lasting more than four hours (priapism), sudden loss of vision or hearing, or severe dizziness that does not improve. If you have any concerns about side effects or how your medicines are working together, contact your GP or pharmacist for advice.

Other Blood Pressure Medicines and Tadalafil Interactions

Irbesartan is just one of many blood pressure medicines, and most can be taken alongside tadalafil with appropriate monitoring. However, some combinations require extra caution. Alpha-blockers (such as doxazosin, tamsulosin, or alfuzosin), often used for prostate symptoms, can cause a more significant drop in blood pressure when combined with tadalafil, so your prescriber will ensure you are stable on the alpha-blocker and start tadalafil at the lowest dose [4].

Other classes of blood pressure medicine—such as ACE inhibitors (like ramipril), calcium channel blockers (like amlodipine), and diuretics (like bendroflumethiazide)—can also add to the blood-pressure-lowering effect of tadalafil, but the interaction is usually manageable [2][4]. Your prescriber will review all your medicines during the consultation.

Never take tadalafil with nitrate medicines (GTN spray, isosorbide mononitrate or dinitrate), nicorandil, riociguat, or recreational drugs called 'poppers' (amyl or alkyl nitrites), as these combinations can cause a dangerous and potentially life-threatening drop in blood pressure [4]. Always declare every medicine, supplement, and recreational substance you use during your consultation.

Scientific References

1. NHS. (n.d.). Erectile dysfunction (impotence). NHS website. https://www.nhs.uk/conditions/erection-problems-erectile-dysfunction/ [accessed 22 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 22 October 2026]
3. Joint Formulary Committee. (n.d.). Tadalafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/tadalafil/ [accessed 22 October 2026]
4. Feldman, H. A., Goldstein, I., Hatzichristou, D. G., Krane, R. J., & McKinlay, J. B. (1994). Impotence and its medical and psychosocial correlates: Results of the Massachusetts Male Aging Study. Journal of Urology, 151(1), 54–61. https://pubmed.ncbi.nlm.nih.gov/8254833/ [accessed 22 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.