Sildenafil and Entresto: Can They Be Taken Together?

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What is sildenafil and how does it work?

Sildenafil is the active ingredient in Viagra and is 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 increased blood flow when you are sexually aroused [3].

Sildenafil is available in 25mg, 50mg and 100mg tablets. The usual starting dose is 50mg, taken about one hour before sexual activity, with a maximum of one dose per day [3]. The medicine does not cause an erection on its own—sexual stimulation is still needed. Effects typically last for around four to five hours, though this varies between individuals.

Common side effects include headache, flushing, indigestion and nasal congestion. More serious but rare side effects include sudden vision or hearing loss, chest pain during sex, or an erection lasting more than four hours (priapism), all of which require urgent medical attention [3].

What is Entresto and why is it prescribed?

Entresto is the brand name for a combination medicine containing sacubitril and valsartan. It is prescribed to treat chronic heart failure in adults whose heart is not pumping blood as well as it should [12]. Entresto works through two mechanisms: valsartan blocks the action of angiotensin II (a hormone that narrows blood vessels), while sacubitril increases levels of natural substances that widen blood vessels and help the heart pump more efficiently.

By reducing the strain on the heart and lowering blood pressure, Entresto helps to reduce the risk of hospitalisation and death in people with heart failure. It is usually taken twice daily and is an important long-term treatment for managing this condition [12].

Because Entresto lowers blood pressure as part of its action, it is important that any other medicines you take—including those for erectile dysfunction—are reviewed by your prescriber to ensure they can be used safely together without causing your blood pressure to drop too low.

How Entresto affects blood pressure

Entresto is designed to lower blood pressure and reduce the workload on your heart. Common side effects include dizziness and low blood pressure, particularly when standing up quickly. Your doctor will monitor your blood pressure regularly while you are taking Entresto to ensure it remains within a safe range [12].

When to get urgent help

• Chest pain during or after sexual activity—stop and call 999 immediately
• Erection lasting more than 4 hours (priapism)—go to A&E
• Sudden loss of vision or hearing—seek urgent medical attention
• Severe dizziness or fainting that does not improve when lying down—call 999 or go to A&E

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

Can you take sildenafil and Entresto together?

Sildenafil and Entresto are not contraindicated, which means there is no absolute ban on taking them together. However, both medicines can lower blood pressure, and using them at the same time may increase the risk of dizziness, light-headedness or fainting, particularly when standing up [3][12].

Your prescriber will need to assess your current blood pressure control, heart function and overall health before deciding whether sildenafil is safe for you. If your heart failure is well controlled and your blood pressure is stable on Entresto, sildenafil may be an option, often starting at a lower dose such as 25mg to minimise the risk of a significant blood pressure drop [3].

It is essential that you declare all your current medicines, including Entresto, during your online consultation at Cured Pharmacy. Our UK-registered prescribers will review your medical history and current treatment to ensure that sildenafil is appropriate and safe for you. Never take sildenafil without this clinical assessment if you have heart failure or are on blood-pressure-lowering medicines.

How the interaction between sildenafil and Entresto works

Both sildenafil and Entresto cause blood vessels to relax and widen (vasodilation), which lowers blood pressure. Sildenafil does this primarily in the blood vessels of the penis and lungs, while Entresto acts more broadly on the cardiovascular system to reduce the strain on the heart [3][12].

When taken together, the blood-pressure-lowering effects can add up. This is not necessarily dangerous, but it does mean that some men may experience symptoms such as dizziness, feeling faint, or a drop in blood pressure when moving from sitting to standing (postural hypotension). These effects are more likely if you are dehydrated, have recently increased your Entresto dose, or drink alcohol.

Your prescriber will take into account your current blood pressure readings, how well your heart failure is controlled, and whether you are on any other medicines that also lower blood pressure. If sildenafil is deemed suitable, you may be advised to start on the lowest dose and to take it at a time when you can sit or lie down if you feel dizzy.

Why starting doses may be lower

If you are taking Entresto or other blood-pressure-lowering medicines, your prescriber may recommend starting sildenafil at 25mg rather than the standard 50mg dose. This cautious approach helps to minimise the risk of a significant drop in blood pressure while still allowing you to benefit from treatment for erectile dysfunction [3].

What your prescriber will check before approving sildenafil and Entresto

During your online consultation, the prescriber will ask detailed questions about your heart health, blood pressure and current medicines. They will want to know how well your heart failure is controlled, whether you have had any recent hospital admissions, and whether you experience symptoms such as chest pain, severe shortness of breath or dizziness [2].

Sexual activity itself places demands on the heart, so the prescriber must ensure that your cardiovascular system is stable enough for this level of exertion. If you have unstable angina, severe heart failure, very low blood pressure, or have had a recent heart attack or stroke, sildenafil may not be suitable [3].

The prescriber will also check for any medicines that are absolutely contraindicated with sildenafil, such as nitrates (GTN spray, isosorbide mononitrate), nicorandil or riociguat. If you are taking any of these, you must not take sildenafil or any other PDE5 inhibitor, as the combination can cause a dangerous fall in blood pressure [3]. Entresto itself is not in this contraindicated category, but the overall picture of your heart health and blood pressure control is what determines safety.

Practical advice for taking sildenafil with Entresto safely

If your prescriber approves sildenafil while you are on Entresto, follow their dosing instructions carefully. Take sildenafil about one hour before planned sexual activity, and do not exceed one dose in 24 hours [3]. Avoid heavy meals beforehand, as they can delay the medicine's effect, and limit alcohol, which can worsen erectile dysfunction and add to the blood-pressure-lowering effect.

Monitor how you feel after taking sildenafil, especially the first time. If you experience dizziness, light-headedness or feel faint, sit or lie down until the symptoms pass. Do not drive or operate machinery if you feel unwell. If you develop chest pain during or after sexual activity, stop and seek urgent medical help—do not take GTN spray or any nitrate medicine if you have used sildenafil in the past 24 hours, as this can cause a life-threatening drop in blood pressure [3].

Keep your GP and heart failure team informed that you are using sildenafil, particularly if your Entresto dose changes or if you start any new medicines. Regular blood pressure monitoring and open communication with your healthcare team will help ensure that both your heart condition and erectile dysfunction are managed safely and effectively.

When to seek urgent help

Seek immediate medical attention if you experience chest pain during sex, an erection lasting more than four hours, sudden loss of vision or hearing, or severe dizziness that does not improve when lying down. Call 999 or go to A&E if you have taken sildenafil and then accidentally use a nitrate medicine, as this combination is dangerous [3].

In summary

• Sildenafil and Entresto are not contraindicated but both can lower blood pressure
• Your prescriber will assess your heart health and blood pressure control before approving sildenafil
• A lower starting dose of sildenafil (25mg) may be recommended if you take Entresto
• Never take sildenafil with nitrates, nicorandil or riociguat—this is dangerous
• Declare all current medicines during your online consultation for safe treatment

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