Tadalafil and Furosemide: Can They Be Taken Together?

Tadalafil and Furosemide: Understanding the Interaction

Published: 21 October 2026

Many men prescribed furosemide (a diuretic or 'water tablet') wonder whether tadalafil and furosemide can be taken together safely. The good news is that there is no absolute contraindication to using these medicines at the same time, but because both can lower blood pressure, your prescriber will carefully assess your cardiovascular health and current blood pressure before approving tadalafil. This page explains how each medicine works, what the interaction means in practice, and the checks your doctor or pharmacist will perform to ensure treatment is safe for you.

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 increased blood flow when you are sexually aroused [3][4]. Tadalafil does not cause an erection on its own—sexual stimulation is still required.

Tadalafil is available in two forms: on-demand tablets (usually 10mg or 20mg) taken at least 30 minutes before sexual activity, with effects lasting up to 36 hours, and daily low-dose tablets (2.5mg or 5mg) taken once a day at the same time [4]. The longer duration of action is why tadalafil is sometimes called the 'weekend pill'. It is the generic version of the branded medicine Cialis.

Because tadalafil relaxes blood vessels, it can cause a mild drop in blood pressure in most men. This effect is usually well tolerated, but it becomes important when tadalafil is combined with other medicines that also lower blood pressure, such as furosemide [4].

What Is Furosemide and Why Is It Prescribed?

Furosemide is a loop diuretic, commonly known as a 'water tablet'. It is prescribed to treat fluid retention (oedema) caused by conditions such as heart failure, liver disease, or kidney disease, and it is also used to manage high blood pressure (hypertension). Furosemide works by helping your kidneys remove excess salt and water from your body through urine.

By reducing fluid volume in the blood vessels, furosemide lowers blood pressure. Common side effects include increased urination, dizziness (especially when standing up quickly), and dehydration if fluid intake is not adequate. Because furosemide affects blood pressure, it is important to consider how it might interact with other medicines that have similar effects.

Men taking furosemide often have underlying cardiovascular conditions, which means a thorough assessment is essential before starting any ED treatment. Your prescriber will review your full medical history, current medicines, and recent blood pressure readings to ensure tadalafil is appropriate and safe for you.

Can You Take Tadalafil and Furosemide Together?

Yes, tadalafil and furosemide can be taken together, and there is no absolute contraindication between these two medicines. However, both can lower blood pressure, so there is a potential for an additive effect—meaning your blood pressure might drop more than it would with either medicine alone [4]. This can lead to symptoms such as dizziness, light-headedness, or fainting, particularly when standing up quickly.

The interaction is not considered dangerous for most men, but it does require careful assessment by a prescriber. Your doctor or pharmacist will check your current blood pressure, review your heart health, and ensure that your cardiovascular system is stable enough for sexual activity. If your blood pressure is already low or poorly controlled, or if you have severe heart failure, tadalafil may not be suitable.

It is essential to declare furosemide (and all other medicines you take) during your online consultation at Cured Pharmacy. Our UK-registered prescribers review every medicine interaction individually and will only approve tadalafil if it is safe for you. Never stop or adjust your furosemide dose without speaking to your GP, as this could worsen your underlying condition.

How the Interaction Works in Plain English

Furosemide lowers blood pressure by reducing the volume of fluid in your blood vessels. Tadalafil lowers blood pressure by relaxing and widening blood vessels. When taken together, these two effects can add up, leading to a greater overall drop in blood pressure than either medicine would cause alone. For most men with stable blood pressure, this is manageable and does not cause problems. However, if your blood pressure is already on the low side, or if you are taking multiple blood-pressure-lowering medicines, the combined effect may cause dizziness or fainting. This is why a prescriber must review your full medication list and recent blood pressure readings before approving tadalafil.

What Your Prescriber Checks Before Approving Tadalafil

When you request tadalafil through Cured Pharmacy, our online consultation asks detailed questions about your medical history, current medicines, and cardiovascular health. If you are taking furosemide, the prescriber will pay particular attention to your blood pressure control, the reason you are taking furosemide (heart failure, kidney disease, or hypertension), and whether you have any symptoms of low blood pressure such as dizziness or fainting.

The prescriber will also check whether sexual activity is safe for you. Conditions such as recent heart attack or stroke (within the past six months), unstable angina, severe heart failure, or very low blood pressure mean that tadalafil is not suitable [2][4]. If you have stable, well-controlled heart disease and your blood pressure is within a safe range, tadalafil is usually appropriate.

You may be started on a lower dose of tadalafil (for example, 10mg on-demand or 2.5mg daily) to minimise the risk of blood pressure drops. Your prescriber may also advise you to monitor for dizziness, especially when standing up, and to avoid heavy alcohol, which can further lower blood pressure and worsen ED. Always follow the prescriber's instructions and report any new symptoms promptly.

Practical Advice for Taking Tadalafil with Furosemide

If your prescriber approves tadalafil, take it exactly as directed. For on-demand tadalafil (10mg or 20mg), take one tablet at least 30 minutes before sexual activity; do not take more than one dose in 24 hours [4]. For daily tadalafil (2.5mg or 5mg), take one tablet at the same time each day, regardless of when you plan to have sex. Swallow the tablet whole with water; it can be taken with or without food.

Continue taking your furosemide as prescribed by your GP. Do not stop, skip, or adjust the dose without medical advice, as this could lead to fluid retention or worsening of your underlying condition. If you experience dizziness, light-headedness, or fainting after starting tadalafil, sit or lie down immediately and contact your GP or pharmacist for advice. These symptoms may indicate that your blood pressure has dropped too low.

Avoid drinking large amounts of alcohol, as this can increase the risk of dizziness and make erectile dysfunction worse. Stay well hydrated, especially if you are taking furosemide, but follow any fluid-restriction advice given by your doctor. If you are prescribed any new medicines or your furosemide dose is changed, inform your prescriber, as this may affect the suitability of tadalafil.

When to Seek Medical Advice

Seek urgent medical help if you experience chest pain or discomfort during or after sexual activity, as this may indicate a heart problem. Call 999 or go to A&E immediately if you have an erection lasting more than four hours (priapism), sudden loss of vision in one or both eyes, or sudden decrease or loss of hearing. Contact your GP or pharmacist promptly if you develop persistent dizziness, fainting, or any other new or worsening symptoms after starting tadalafil. Do not ignore warning signs—early assessment can prevent serious complications.

Other Medicines That Interact with Tadalafil

While tadalafil and furosemide can usually be taken together safely, there are some medicines that must never be combined with tadalafil. Do not take tadalafil if you are using nitrates (such as GTN spray, isosorbide mononitrate, or isosorbide dinitrate), nicorandil, riociguat, or recreational drugs called 'poppers' (amyl or alkyl nitrites). Combining tadalafil with any of these can cause a dangerous, life-threatening drop in blood pressure [3][4].

Alpha-blockers (such as doxazosin, tamsulosin, alfuzosin, or terazosin), used for prostate problems or high blood pressure, can also interact with tadalafil, increasing the risk of dizziness and low blood pressure. If you take an alpha-blocker, your prescriber will ensure you are stable on that medicine and will start you on the lowest dose of tadalafil [4]. Some antibiotics and antifungal medicines (such as clarithromycin, erythromycin, ketoconazole, and itraconazole) can increase tadalafil levels in your blood, requiring dose adjustments.

Other blood-pressure medicines (such as ACE inhibitors, angiotensin receptor blockers, beta-blockers, or calcium-channel blockers) may add to the blood-pressure-lowering effect of tadalafil, but this is usually manageable with careful monitoring. Always declare every medicine, supplement, and herbal remedy you take during your consultation, even if you think it is unrelated. Our prescribers check every interaction individually to ensure your safety.

Grapefruit Juice and Other Lifestyle Factors

Avoid drinking grapefruit juice while taking tadalafil, as it can increase the level of the medicine in your blood and raise the risk of side effects. Heavy alcohol consumption can worsen erectile dysfunction and increase the likelihood of dizziness and low blood pressure when combined with tadalafil. Smoking and recreational drug use (especially cocaine and 'poppers') are also harmful and can interact dangerously with ED treatment. If you need support to stop smoking or reduce alcohol intake, speak to your GP or pharmacist, who can signpost you to local services.

Scientific References

1. National Institute for Health and Care Excellence. (n.d.). Erectile dysfunction. Clinical Knowledge Summaries. https://cks.nice.org.uk/topics/erectile-dysfunction/ [accessed 21 October 2026]
2. Joint Formulary Committee. (n.d.). Sildenafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/sildenafil/ [accessed 21 October 2026]
3. Joint Formulary Committee. (n.d.). Tadalafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/tadalafil/ [accessed 21 October 2026]
4. NHS. (n.d.). Erectile dysfunction (impotence). https://www.nhs.uk/conditions/erection-problems-erectile-dysfunction/ Accessed 21 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.