Tadalafil and Nitrates: Never Take Them Together
Learn why this combination is dangerous and what safer alternatives exist after a UK pharmacist-led consultation.
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Tadalafil and Nitrates: A Dangerous Combination You Must Avoid
Published: 16 October 2026
Tadalafil and nitrates must never be taken together because the combination can cause a severe and potentially life-threatening drop in blood pressure. Tadalafil is a prescription medicine used to treat erectile dysfunction (ED), while nitrates—such as GTN spray, isosorbide mononitrate, and isosorbide dinitrate—are commonly prescribed for angina (chest pain caused by reduced blood flow to the heart). Both medicines work by relaxing and widening blood vessels, and when combined, their effects multiply in a way that can lead to dizziness, fainting, heart attack, or stroke [3][4].
Carry a Medicine Card
If you take tadalafil, keep a note in your wallet or phone listing all your medicines and when you last took tadalafil. In an emergency, this information could save your life by preventing healthcare staff from giving you nitrates.
What Is Tadalafil and How Does It Work?
Tadalafil is a phosphodiesterase type 5 (PDE5) inhibitor licensed in the UK for the treatment of erectile dysfunction. It is the active ingredient in branded Cialis and is also available as a generic medicine. Tadalafil works by blocking the PDE5 enzyme, which allows blood vessels in the penis to relax and widen when you are sexually aroused, making it easier to achieve and maintain an erection [4].
Tadalafil is available in two forms: on-demand tablets (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 to provide continuous support. Sexual stimulation is still required for the medicine to work. Tadalafil is only available on prescription in the UK after a consultation with a registered prescriber, who will check your medical history and current medicines to ensure it is safe for you [2][4].
What Are Nitrates and Why Are They Prescribed?
Nitrates are a group of medicines used to prevent and relieve angina, which is chest pain caused by narrowed coronary arteries reducing blood flow to the heart muscle. Common nitrate medicines include glyceryl trinitrate (GTN) spray or tablets, isosorbide mononitrate, and isosorbide dinitrate. Nitrates work by relaxing and widening blood vessels throughout the body, which reduces the workload on the heart and improves blood flow to the heart muscle [3][4].
GTN spray is often used for rapid relief of angina symptoms and is kept by patients for use when chest pain occurs or before activities that might trigger it. Long-acting nitrates such as isosorbide mononitrate are taken regularly to prevent angina attacks. Because nitrates lower blood pressure as part of their action, they must be used carefully and never combined with certain other medicines, including all PDE5 inhibitors like tadalafil [4].
Common Nitrate Medicines in the UK
Nitrate medicines you may be prescribed include glyceryl trinitrate (GTN) spray (brand names Nitrolingual, GTN 400 mcg), GTN tablets or patches, isosorbide mononitrate tablets (Elantan, Imdur, Ismo, Monosorb), and isosorbide dinitrate tablets or spray. All of these medicines are contraindicated with tadalafil and other PDE5 inhibitors. If you use any form of nitrate medicine—whether it is a spray you keep in your pocket for emergencies or a tablet you take every day—you must not take tadalafil [3][4].
When to get urgent help
- Severe dizziness, fainting, or loss of consciousness after taking tadalafil and a nitrate—call 999 immediately.
- Chest pain while taking or after taking tadalafil—do not use GTN spray; call 999 and tell them you have taken tadalafil.
- Blurred vision, confusion, rapid heartbeat, or feeling extremely unwell after combining these medicines—go to A&E now.
- An erection lasting more than 4 hours (priapism)—go to A&E immediately to prevent permanent damage.
- Sudden loss of vision or hearing after taking tadalafil—stop taking it and seek urgent medical attention the same day.
Call 999 or go to A&E in an emergency, or contact NHS 111 for urgent advice.
Why Tadalafil and Nitrates Must Never Be Taken Together
The combination of tadalafil and nitrates is absolutely contraindicated because both medicines relax and widen blood vessels, and their effects are additive. When taken together, they can cause a sudden, severe, and uncontrollable drop in blood pressure (hypotension). This can lead to dizziness, fainting, loss of consciousness, heart attack, stroke, or even death. The risk is present regardless of the dose of either medicine or the time gap between taking them [3][4].
Tadalafil has a long duration of action—its effects can last up to 36 hours after a single dose. This means that even if you take a nitrate medicine a day or more after taking tadalafil, the interaction can still occur. For this reason, if you have taken tadalafil, you must not use any nitrate medicine for at least 48 hours, and you should inform any healthcare professional treating you (including paramedics and A&E staff) that you have recently taken tadalafil [4][12].
If you develop chest pain while taking tadalafil, do not use GTN spray or any other nitrate. Seek urgent medical help immediately and tell the healthcare team that you have taken tadalafil. They will need to use alternative treatments for your chest pain that do not interact dangerously with tadalafil [3][4].
What Your Prescriber Checks Before Prescribing Tadalafil
Before prescribing tadalafil, a UK prescriber will ask detailed questions about your medical history and current medicines to ensure it is safe for you. They will specifically ask whether you take any nitrate medicines for angina or chest pain, or nicorandil (another heart medicine that interacts in the same way). If you use any of these medicines, tadalafil will not be prescribed [2][4].
The prescriber will also check for other heart conditions that may make sexual activity inadvisable, such as a recent heart attack or stroke (within the past six months), unstable angina, severe heart failure, very low blood pressure, or uncontrolled high blood pressure. They will ask about other medicines you take, including alpha-blockers for prostate problems or high blood pressure, and medicines that can affect how tadalafil is broken down in the body, such as certain antibiotics and antifungals [2][4].
It is essential that you provide complete and honest information during your consultation. Do not withhold information about nitrate use or heart problems because you are worried you will not be able to get treatment for ED—there may be safer alternatives available, and your prescriber can discuss these with you. Never obtain tadalafil without a proper medical consultation, as this puts your health at serious risk [2].
Other Medicines That Interact Like Nitrates
In addition to nitrates, tadalafil must not be taken with nicorandil (a potassium-channel activator used for angina), riociguat (used for pulmonary hypertension), or amyl nitrite and alkyl nitrites (recreational drugs known as 'poppers'). All of these medicines can cause the same dangerous drop in blood pressure when combined with tadalafil. You must also never take tadalafil at the same time as another PDE5 inhibitor such as sildenafil, vardenafil, or avanafil [3][4][12].
At a glance
Alternatives for Men Who Take Nitrates and Have Erectile Dysfunction
If you take nitrate medicines for angina, you cannot safely use tadalafil or any other PDE5 inhibitor (including sildenafil, vardenafil, or avanafil). However, erectile dysfunction is still treatable, and you should discuss your options with your GP or a specialist. It is important not to simply accept ED as inevitable—treatment can significantly improve quality of life, and your doctor will want to help you find a safe solution [1][2].
Alternative treatments that do not interact with nitrates include vacuum erection devices (vacuum pumps), which use suction to draw blood into the penis and are held in place with a constriction ring. These are available on NHS prescription and can be effective for many men. Another option is alprostadil, a medicine that works differently from PDE5 inhibitors. Alprostadil can be applied as a cream (Vitaros) inserted into the opening of the penis, or given as an injection into the side of the penis (Caverject). These treatments work locally and do not cause the same blood pressure effects as PDE5 inhibitors, so they can be used by men taking nitrates [2][7].
Your GP may also review your heart condition and nitrate treatment to see whether any adjustments can be made, though this will depend on your individual circumstances. Some men may be able to have their angina managed differently, but this decision must only be made by a cardiologist or your GP—never stop taking nitrates without medical advice, as this could put you at risk of a heart attack [1][2].
What to Do If You Have Taken Tadalafil and Nitrates Together
If you have accidentally taken tadalafil and a nitrate medicine together, or if you have taken tadalafil and then develop chest pain and are considering using your GTN spray, you must seek urgent medical help immediately. Call 999 or go straight to your nearest A&E department. Do not drive yourself—ask someone else to take you or wait for an ambulance. Tell the healthcare team exactly what medicines you have taken and when, so they can treat you safely and avoid giving you further nitrates [3][4].
Symptoms of a dangerous drop in blood pressure include severe dizziness, feeling faint or lightheaded, blurred vision, confusion, nausea, rapid or irregular heartbeat, chest pain, or loss of consciousness. These symptoms require emergency treatment. Even if you feel only mildly unwell, it is important to seek medical advice, as blood pressure can continue to fall and the situation can become life-threatening [4][12].
If you are being treated for chest pain or a heart problem and a healthcare professional is about to give you a nitrate medicine, make sure you tell them immediately if you have taken tadalafil in the past 48 hours. This information could be life-saving. Consider carrying a card in your wallet or adding a note to your phone that lists the medicines you take, including any recent use of tadalafil, so that emergency responders have this information if you are unable to communicate [4].
Informing Healthcare Professionals
Always inform any doctor, nurse, pharmacist, dentist, or paramedic that you take tadalafil, especially if you are receiving treatment for chest pain, heart problems, or high blood pressure. This includes routine appointments, emergency situations, and before any surgery or procedure. If you are admitted to hospital, make sure the medical team knows about all your medicines, including tadalafil and when you last took it. This will help them choose safe treatments and avoid dangerous interactions [2][4].
In summary
- Tadalafil and nitrates must never be taken together—they cause a dangerous drop in blood pressure that can be life-threatening.
- Nitrates include GTN spray, isosorbide mononitrate, isosorbide dinitrate, and nicorandil, all used for angina and chest pain.
- If you take nitrates, safer ED treatments include vacuum devices and alprostadil cream or injections—discuss with your GP.
- If you get chest pain after taking tadalafil, call 999 immediately and do not use GTN spray or any nitrate medicine.
- Always tell any healthcare professional if you have taken tadalafil in the past 48 hours, especially in an emergency.
Scientific References
- NHS. (n.d.). Erectile dysfunction (impotence). NHS website. https://www.nhs.uk/conditions/erection-problems-erectile-dysfunction/ [accessed 16 October 2026]
- 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]
- Joint Formulary Committee. (n.d.). Sildenafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/sildenafil/ [accessed 16 October 2026]
- Joint Formulary Committee. (n.d.). Tadalafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/tadalafil/ [accessed 16 October 2026]
- Joint Formulary Committee. (n.d.). Alprostadil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/alprostadil/ [accessed 16 October 2026]
- Electronic Medicines Compendium. (n.d.). Summaries of Product Characteristics and Patient Information Leaflets. https://www.medicines.org.uk/emc/ [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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