Sildenafil and Indapamide: Can You Take Them Together?

Sildenafil and Indapamide: What You Need to Know About Taking Them Together

Published: 16 October 2026

Many men wonder whether sildenafil and indapamide can be taken together safely. The good news is that sildenafil, a medicine used to treat erectile dysfunction, can usually be prescribed alongside indapamide, a diuretic (water tablet) used to treat high blood pressure, but your prescriber will need to check your blood pressure and overall cardiovascular health first. This page explains how these medicines work, what the interaction means for you, and the practical steps to take them safely.

What is sildenafil and indapamide?

Sildenafil is a medicine licensed in the UK 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 [3]. Sildenafil is the active ingredient in Viagra and is available in 25mg, 50mg, and 100mg tablets. You take it about one hour before sexual activity, and it works only when you are sexually stimulated. The effect lasts for around four to six hours, and you should not take it more than once a day.

Indapamide is a diuretic (sometimes called a 'water tablet') used to treat high blood pressure (hypertension). It works by helping your kidneys remove excess salt and water from your body through urine, which lowers the volume of fluid in your blood vessels and reduces blood pressure. Indapamide is usually taken once a day in the morning. High blood pressure itself is a risk factor for erectile dysfunction, so treating it is important for your overall health and may improve ED over time [1].

Can you take sildenafil and indapamide together?

Yes, sildenafil and indapamide can usually be taken together, but your prescriber must assess your individual situation first. Both medicines can lower blood pressure: indapamide does so as its main action, and sildenafil can cause a modest drop in blood pressure as a side effect [3]. When taken together, there is a possibility that the blood-pressure-lowering effects may add up, which could lead to symptoms such as dizziness, light-headedness, or fainting, especially when you stand up quickly.

This interaction is not usually dangerous for most men, and many people take both medicines without problems. However, your prescriber will check your current blood pressure, review your full list of medicines, and ensure your cardiovascular system is healthy enough for sexual activity before prescribing sildenafil. If your blood pressure is well controlled on indapamide and you have no other significant heart or blood vessel problems, sildenafil is often suitable. Your prescriber may start you on a lower dose of sildenafil to minimise the risk of a blood pressure drop [2].

How the interaction works

Indapamide lowers blood pressure by reducing the amount of fluid in your blood vessels. Sildenafil relaxes the smooth muscle in blood vessel walls, which also lowers blood pressure slightly. When you take both medicines, these effects can combine. For most men, this is not a problem, but if your blood pressure drops too much, you may feel dizzy or faint. The risk is higher if you are dehydrated, have been drinking alcohol, or stand up suddenly. Your body usually adjusts to the combination over time, and any initial dizziness often settles within a few doses.

What your prescriber checks before prescribing sildenafil and indapamide

Before prescribing sildenafil to someone taking indapamide, a UK prescriber will carry out a careful assessment. They will ask about your current blood pressure readings, how well controlled your blood pressure is, and whether you have ever experienced dizziness or fainting. They will also ask about any other medicines you take, because some combinations (such as sildenafil with nitrates or nicorandil) are not safe. You must tell your prescriber about every medicine you use, including over-the-counter products and herbal supplements.

Your prescriber will also check whether your heart and blood vessels are healthy enough for sexual activity. This is important because sex is a form of physical exertion that raises your heart rate and blood pressure temporarily. If you have recently had a heart attack or stroke, have unstable angina, severe heart failure, or very low blood pressure, sildenafil may not be suitable [2][3]. The online consultation at Cured Pharmacy includes all these checks, and a UK-registered prescriber reviews every request before approving a prescription.

Practical advice for taking sildenafil with indapamide

If your prescriber approves sildenafil while you are taking indapamide, follow these practical tips to use both medicines safely. Take indapamide in the morning as prescribed, and take sildenafil about one hour before you plan to have sex (it needs sexual stimulation to work). Start with the lowest effective dose of sildenafil, which is often 50mg, though your prescriber may recommend 25mg initially if you are at higher risk of a blood pressure drop. Do not take sildenafil more than once in 24 hours.

Avoid drinking large amounts of alcohol when taking sildenafil, as alcohol can lower blood pressure further and make erectile dysfunction worse. Stay well hydrated, especially in hot weather or if you are exercising, because dehydration can increase the risk of dizziness. When you stand up from sitting or lying down, do so slowly to give your blood pressure time to adjust. If you feel dizzy or light-headed after taking sildenafil, sit or lie down until the feeling passes. If dizziness is severe or does not go away, contact your GP or pharmacist for advice.

What to do if you feel unwell

Most men tolerate sildenafil and indapamide together without problems, but if you experience persistent dizziness, fainting, or a very fast or slow heartbeat, stop taking sildenafil and seek medical advice. If you develop chest pain during or after sex, do not take another dose of sildenafil and call 999 or go to A&E immediately. Never take sildenafil with nitrate medicines (such as GTN spray or isosorbide mononitrate) or nicorandil, as this combination can cause a dangerous drop in blood pressure. If you are ever prescribed a new medicine, always tell the prescriber or pharmacist that you take sildenafil.

Other blood pressure medicines and sildenafil interactions

Indapamide is just one of many medicines used to treat high blood pressure. Other common blood pressure medicines include ACE inhibitors (such as ramipril or lisinopril), angiotensin receptor blockers (ARBs, such as losartan or candesartan), calcium channel blockers (such as amlodipine), and beta-blockers (such as bisoprolol or atenolol). Sildenafil can be taken with most of these medicines, and the same principle applies: both may lower blood pressure, so your prescriber will check that your blood pressure is stable and that you are not at high risk of dizziness or fainting.

One group of blood pressure medicines that requires extra caution is alpha-blockers, such as doxazosin, tamsulosin, or alfuzosin. These are often used to treat symptoms of an enlarged prostate as well as high blood pressure. The combination of sildenafil and an alpha-blocker carries a higher risk of low blood pressure and dizziness. If you take an alpha-blocker, your prescriber will usually ensure you are stable on that medicine first, then start you on the lowest dose of sildenafil [3]. You should not take both medicines at the same time of day; spacing them out can reduce the risk of a blood pressure drop.

When sildenafil and indapamide should not be used together

There are some situations where sildenafil should not be prescribed, even if you are taking indapamide. If your blood pressure is very low (hypotension), sildenafil could make it worse and cause fainting or collapse. If you have recently had a heart attack or stroke (usually within the last six months), or if you have unstable angina or severe heart failure, your doctor may advise that sexual activity and sildenafil are not safe for you at this time [2][3].

Sildenafil must never be taken with nitrate medicines (such as glyceryl trinitrate spray, isosorbide mononitrate, or isosorbide dinitrate), nicorandil, or riociguat, because the combination can cause a life-threatening drop in blood pressure. It must also not be taken with recreational drugs called 'poppers' (amyl or alkyl nitrites) or with another PDE5 inhibitor (such as tadalafil, vardenafil, or avanafil). If you are taking any of these medicines or substances, do not take sildenafil. Always declare every medicine and supplement you use during your consultation, so your prescriber can check for interactions.

Alternatives if sildenafil is not suitable

If sildenafil is not suitable for you because of an interaction or other health reason, other options may be available. Tadalafil (Cialis) is another PDE5 inhibitor that works in a similar way but lasts longer (up to 36 hours) and can also be taken as a low daily dose. Vardenafil (Levitra) and avanafil (Spedra) are also PDE5 inhibitors with slightly different profiles. All of these have similar interactions with blood pressure medicines, so the same precautions apply. Non-tablet treatments include Eroxon gel (a medical device available without prescription), Vitaros cream, and Caverject injections (both prescription-only). Your prescriber or GP can discuss which option is best for you [1][2].

Scientific References

1. NHS. (n.d.). Erectile dysfunction (impotence). NHS website. https://www.nhs.uk/conditions/erection-problems-erectile-dysfunction/ [accessed 16 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 16 October 2026]
3. Joint Formulary Committee. (n.d.). Sildenafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/sildenafil/ [accessed 16 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.

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