Sildenafil and Zopiclone: Can You Take Them Together?

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Sildenafil and Zopiclone: Understanding the Interaction

Published: 18 October 2026

Many men wonder whether sildenafil and zopiclone can be taken together safely. Sildenafil is a PDE5 inhibitor used to treat erectile dysfunction, while zopiclone is a sleeping tablet prescribed for short-term insomnia. The good news is that no major direct interaction between these two medicines is commonly reported in clinical practice, but there are important safety considerations your prescriber will check before approving the combination.

What is sildenafil and how does it work?

Sildenafil, commonly known by the brand name Viagra, 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 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. The medicine only works when you are sexually stimulated—it does not cause an automatic erection [3].

Common side effects include headache, facial 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]. Sildenafil is available on prescription after a clinical assessment by a UK-registered prescriber, who will check your medical history and current medicines to ensure it is safe for you.

What is zopiclone and why is it prescribed?

Zopiclone is a prescription-only sleeping tablet used for the short-term treatment of severe insomnia. It belongs to a class of medicines known as non-benzodiazepine hypnotics (or 'Z-drugs'), which help you fall asleep more quickly and reduce the number of times you wake during the night.

Zopiclone is typically prescribed in 3.75mg or 7.5mg doses, taken just before bedtime. It is usually recommended for no more than two to four weeks, as longer use can lead to tolerance and dependence. Common side effects include a bitter or metallic taste in the mouth, drowsiness the next day, dry mouth, and dizziness.

Because zopiclone causes drowsiness and can impair coordination and judgement, you should not drive, operate machinery, or make important decisions while taking it or the morning after. Alcohol should be avoided, as it increases the sedative effect and the risk of serious side effects. Your GP or prescriber will review your sleep difficulties and overall health before prescribing zopiclone.

How zopiclone affects your body

Zopiclone works by enhancing the activity of a neurotransmitter called GABA (gamma-aminobutyric acid) in the brain, which has a calming effect on the nervous system. This helps to reduce brain activity, making it easier to fall asleep. The medicine is absorbed quickly, usually taking effect within about one hour, and is broken down by the liver.

Can you take sildenafil and zopiclone together?

There is no major direct pharmacological interaction between sildenafil and zopiclone that would make the combination unsafe in most cases. The two medicines work on different systems in the body: sildenafil affects blood vessels and blood flow, while zopiclone acts on the central nervous system to promote sleep.

However, both medicines can cause dizziness and a drop in blood pressure, particularly when you stand up quickly (postural hypotension). Taking them together may add to these effects, so it is important to be cautious, especially when first starting the combination or if you are also taking other medicines that lower blood pressure.

Your prescriber will review your full medical history and all current medicines during your consultation to ensure the combination is appropriate for you. They will consider factors such as your age, overall health, other medications, and whether you have any conditions that increase the risk of side effects. You should never take sildenafil or zopiclone without a prescription, and you must declare all medicines—including over-the-counter products and herbal supplements—during your assessment.

What your prescriber checks before approving sildenafil and zopiclone

When you request sildenafil through an online consultation at Cured Pharmacy, a UK-registered prescriber will review your medical questionnaire carefully. They will check for any contraindications to sildenafil, such as recent heart attack or stroke, unstable angina, severe heart failure, very low blood pressure, or use of nitrate medicines (GTN spray, isosorbide mononitrate or dinitrate), nicorandil, riociguat, or recreational drugs called 'poppers' [3].

If you are taking zopiclone, the prescriber will assess whether the combination is safe based on your individual circumstances. They will look at your blood pressure, any history of dizziness or fainting, and whether you are taking other medicines that could interact. For example, if you also take blood pressure medicines or alpha-blockers (such as doxazosin or tamsulosin), the prescriber may recommend starting on a lower dose of sildenafil to minimise the risk of a sudden drop in blood pressure [3].

The prescriber will also consider the timing of your doses. Because zopiclone is taken at bedtime and sildenafil is usually taken about an hour before sexual activity, the two medicines are often taken at different times of day, which can reduce the chance of overlapping side effects. If you have any concerns or experience unusual symptoms, you should contact your prescriber or GP for advice.

Medicines that must never be taken with sildenafil

Do not take sildenafil together with nitrates (such as GTN spray, isosorbide mononitrate, or isosorbide dinitrate), nicorandil, riociguat, amyl or alkyl nitrites (poppers), or another PDE5 inhibitor. These combinations can cause a dangerous, potentially life-threatening drop in blood pressure [3]. Always tell your prescriber about every medicine you take, including those prescribed by your GP, bought over the counter, or obtained online.

Practical advice for taking sildenafil and zopiclone safely

If your prescriber approves the combination of sildenafil and zopiclone, follow their instructions carefully. Take zopiclone only at bedtime, just before you go to sleep, and ensure you can stay in bed for seven to eight hours. Take sildenafil about one hour before planned sexual activity, on an empty stomach or after a light meal, as a heavy or high-fat meal can delay its effect [3].

Avoid alcohol when taking either medicine. Alcohol can worsen erectile dysfunction, increase drowsiness from zopiclone, and add to the blood-pressure-lowering effects of sildenafil, raising the risk of dizziness or fainting. Grapefruit juice should also be avoided, as it can increase the levels of sildenafil in your blood and raise the risk of side effects [3].

Be cautious when standing up from sitting or lying down, especially at night or first thing in the morning, as both medicines can cause dizziness. If you feel dizzy, sit or lie down until it passes. Do not drive or operate machinery if you feel drowsy or unsteady. If you experience any unusual symptoms—such as severe dizziness, chest pain, an erection lasting more than four hours, or sudden vision or hearing loss—seek urgent medical help immediately.

Other medicines and health conditions to discuss with your prescriber

In addition to zopiclone, you must tell your prescriber about all other medicines you are taking. Alpha-blockers (such as doxazosin, tamsulosin, alfuzosin, or terazosin) can interact with sildenafil, increasing the risk of low blood pressure and dizziness. If you take an alpha-blocker, your prescriber will ensure you are stable on that medicine and may start you on a lower dose of sildenafil [3].

Certain medicines that affect liver enzymes—such as ritonavir, cobicistat, Paxlovid, ketoconazole, itraconazole, and clarithromycin—can raise the levels of sildenafil in your blood, increasing the risk of side effects. Conversely, medicines like rifampicin, carbamazepine, phenytoin, and St John's wort can reduce the effectiveness of sildenafil [3]. Your prescriber will check the Summary of Product Characteristics (SmPC) for any medicine you are taking to ensure the combination is safe.

You should also declare any health conditions, particularly heart disease, high or low blood pressure, liver or kidney problems, bleeding disorders, stomach ulcers, or any history of sudden vision loss (NAION) or inherited retinal disorders. If you have not seen your GP about your erectile dysfunction, it is important to do so, as ED can be an early warning sign of cardiovascular disease or diabetes [1][2]. Cured Pharmacy's online consultation is designed to identify any red flags and will refer you to your GP if necessary.

When to see your GP

You should see your GP if you have new or worsening erectile dysfunction, as it may indicate an underlying health condition such as diabetes, high blood pressure, or heart disease [1][2]. Your GP can arrange tests, review your medicines, and discuss lifestyle changes or treatments. If you experience chest pain during sex, an erection lasting more than four hours, or sudden loss of vision or hearing, seek emergency medical help immediately.

Scientific References

1. NHS. (n.d.). Erectile dysfunction (impotence). NHS website. https://www.nhs.uk/conditions/erection-problems-erectile-dysfunction/ [accessed 18 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 18 October 2026]
3. Joint Formulary Committee. (n.d.). Sildenafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/sildenafil/ [accessed 18 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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