Tadalafil and Spironolactone: Can They Be Taken Together?

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Key takeaways

• No major direct interaction between tadalafil and spironolactone is commonly reported in clinical practice.
• Both medicines can lower blood pressure, so your prescriber will check your cardiovascular health first.
• Do not take tadalafil with nitrates, nicorandil, riociguat, poppers, or another PDE5 inhibitor.
• Declare all your medicines during your consultation, including spironolactone and any blood pressure treatments.
• Seek urgent help for chest pain during sex, erection lasting over four hours, or sudden vision or hearing loss.

What is tadalafil and spironolactone used for?

Tadalafil is a prescription medicine licensed in the UK for 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 [4]. Tadalafil is available as on-demand tablets (10 mg or 20 mg, taken at least 30 minutes before sex, with effects lasting up to 36 hours) or as a daily low-dose tablet (2.5 mg or 5 mg). It does not work without sexual stimulation and will not increase your sex drive.

Spironolactone is a potassium-sparing diuretic (water tablet) that works by blocking the hormone aldosterone. It is commonly prescribed for conditions such as heart failure, high blood pressure, fluid retention (oedema), and primary hyperaldosteronism [12]. In some cases, spironolactone is also used off-label for hormonal acne or hirsutism in women. Because it affects fluid balance and blood pressure, your prescriber will consider your overall cardiovascular health when assessing whether tadalafil is suitable for you.

Is there an interaction between tadalafil and spironolactone?

There is no major direct drug interaction between tadalafil and spironolactone reported in standard clinical references [2][4]. Spironolactone does not significantly affect the way tadalafil is broken down in the body, and tadalafil does not interfere with spironolactone's mechanism of action. However, both medicines can lower blood pressure, so there is a theoretical risk that taking them together might add to this effect and cause dizziness or light-headedness, particularly when you stand up quickly.

This additive blood-pressure-lowering effect is not unique to spironolactone—it applies to many blood pressure medicines, including other diuretics, ACE inhibitors, angiotensin receptor blockers, and calcium channel blockers [2][4]. The key is that your prescriber will assess your current blood pressure, the stability of your heart condition, and whether you experience symptoms such as dizziness before deciding if tadalafil is safe for you. Most men taking spironolactone can use tadalafil without problems, provided their blood pressure is well controlled and they are otherwise healthy enough for sexual activity.

How the interaction works in plain English

Tadalafil relaxes blood vessels throughout the body, which can cause a modest drop in blood pressure. Spironolactone helps your body get rid of excess fluid and also lowers blood pressure by blocking aldosterone. When you take both medicines, their blood-pressure-lowering effects can add together. For most people, this is not a problem, but if your blood pressure is already on the low side or if you are taking several blood pressure medicines, you might feel dizzy or faint, especially when standing up. Your prescriber will check your blood pressure and medical history during your consultation to make sure tadalafil is safe for you.

At a glance

What does your prescriber check before prescribing tadalafil and spironolactone together?

Before prescribing tadalafil, your prescriber will review your full medical history and all current medicines, including spironolactone [2]. They will ask about your blood pressure, any history of heart disease, stroke, or heart failure, and whether you experience chest pain, dizziness, or fainting. They will also check whether you are taking any medicines that are contraindicated with tadalafil, such as nitrates (GTN spray, isosorbide mononitrate), nicorandil, riociguat, or another PDE5 inhibitor [4]. If you are on any of these, you must not take tadalafil.

Your prescriber will also want to know if you are on an alpha-blocker (such as doxazosin or tamsulosin), as these medicines carry a higher risk of low blood pressure when combined with tadalafil. If you are stable on an alpha-blocker, you will usually be started on the lowest dose of tadalafil [4]. Because spironolactone is often prescribed for heart or kidney conditions, your prescriber will assess whether your cardiovascular system is healthy enough for sexual activity. If you have severe heart failure, very low blood pressure, or unstable angina, tadalafil may not be suitable [2][4].

Declaring all your medicines

It is essential to list every medicine you take during your online consultation, including prescription medicines, over-the-counter treatments, herbal remedies, and supplements. This includes spironolactone, any other blood pressure or heart medicines, and any treatments for prostate problems. Do not stop or change any prescribed medicine without speaking to your GP or prescriber first. If you start a new medicine after being prescribed tadalafil, check with your pharmacist or GP whether it is safe to continue using tadalafil.

Practical advice for taking tadalafil and spironolactone safely

If your prescriber confirms that tadalafil is safe for you, take it exactly as directed. For on-demand tadalafil (10 mg or 20 mg), take one tablet at least 30 minutes before sexual activity; do not take more than one dose in 24 hours [4]. For daily tadalafil (2.5 mg or 5 mg), take one tablet at the same time each day, whether or not you plan to have sex. Tadalafil can be taken with or without food, but avoid drinking large amounts of alcohol, as this can make erectile dysfunction worse and increase the risk of dizziness or low blood pressure.

Continue taking spironolactone as prescribed by your GP. Do not stop or reduce your dose without medical advice, as this could worsen your heart or blood pressure condition. If you feel dizzy, light-headed, or faint after taking tadalafil, sit or lie down until the feeling passes. Avoid driving or operating machinery if you feel unsteady. If dizziness persists or worsens, contact your GP or pharmacist. Stand up slowly from sitting or lying positions, especially first thing in the morning, to minimise the risk of postural hypotension (a sudden drop in blood pressure on standing).

Warning signs and when to seek help with tadalafil and spironolactone

Most men tolerate tadalafil well, but you should be aware of warning signs that need urgent attention. If you develop chest pain during or after sex, stop sexual activity immediately, sit down, and call 999. Do not take GTN or any nitrate medicine if you have used tadalafil in the past 48 hours, as this combination can cause a dangerous drop in blood pressure [4]. If you experience a sudden loss of vision in one or both eyes, stop taking tadalafil and seek urgent medical help, as this could be a sign of non-arteritic anterior ischaemic optic neuropathy (NAION), a rare but serious condition.

If you have an erection that lasts longer than four hours (priapism), go to A&E straight away, as this requires emergency treatment to prevent permanent damage. Sudden hearing loss or ringing in the ears is also a reason to stop tadalafil and see a doctor urgently. If you experience severe dizziness, fainting, or a very fast or irregular heartbeat, contact your GP or call 111 for advice. These symptoms could indicate that your blood pressure has dropped too low or that there is an issue with your heart rhythm.

Common side effects

Common side effects of tadalafil include headache, indigestion, back pain, muscle aches, flushing, and a blocked or runny nose [4]. These are usually mild and go away on their own. If they are troublesome, speak to your pharmacist or prescriber. Spironolactone can cause increased urination, dizziness, breast tenderness (in men), and changes in potassium levels [12]. Your GP will monitor your kidney function and potassium levels with blood tests while you are on spironolactone. If you notice any new or worsening symptoms after starting tadalafil, contact your healthcare provider for advice.

Other medicines and lifestyle factors to consider with tadalafil and spironolactone

In addition to spironolactone, you should tell your prescriber about any other blood pressure medicines you take, such as ACE inhibitors (ramipril, lisinopril), angiotensin receptor blockers (losartan, candesartan), beta-blockers (bisoprolol, atenolol), or calcium channel blockers (amlodipine, diltiazem). These can all add to the blood-pressure-lowering effect of tadalafil [2][4]. If you are on an alpha-blocker for prostate symptoms (doxazosin, tamsulosin, alfuzosin), your prescriber will start you on a lower dose of tadalafil and ensure you are stable on the alpha-blocker first.

Avoid drinking grapefruit juice while taking tadalafil, as it can increase the level of tadalafil in your blood and raise the risk of side effects [4]. Limit alcohol to a moderate amount (no more than two units), as heavy drinking can worsen erectile dysfunction and increase the risk of dizziness. If you are taking medicines that strongly inhibit the enzyme CYP3A4—such as ritonavir, cobicistat, ketoconazole, itraconazole, or clarithromycin—your prescriber may need to adjust your tadalafil dose or choose a different treatment [4]. Always check with your pharmacist before starting any new medicine, including over-the-counter or herbal products such as St John's wort, which can reduce the effectiveness of tadalafil.

When to see your GP

If you are experiencing erectile dysfunction for the first time, it is important to see your GP for a full assessment. ED can be an early warning sign of cardiovascular disease, diabetes, or other health conditions that need treatment [1][2]. Your GP can check your blood pressure, cholesterol, blood sugar, and hormone levels, and discuss lifestyle changes such as losing weight, stopping smoking, reducing alcohol, and increasing physical activity. Treating the underlying cause can often improve ED without the need for medication. If you have been using tadalafil and it stops working, or if your erectile dysfunction worsens, speak to your GP or prescriber for a review.

When to get urgent help

• Chest pain during or after sex—call 999 and do not take nitrates if you have used tadalafil in the past 48 hours
• Erection lasting longer than four hours—go to A&E immediately to prevent permanent damage
• Sudden loss of vision in one or both eyes—stop tadalafil and seek urgent medical help
• Sudden hearing loss or ringing in the ears—stop tadalafil and see a doctor urgently
• Severe dizziness, fainting, or very fast or irregular heartbeat—contact your GP or call 111 for advice

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

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