Tadalafil and Selegiline: Can They Be Taken Together?

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What is tadalafil and how does it work?

Tadalafil is a prescription medicine used to treat erectile dysfunction (ED) in men. 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 the active ingredient in branded Cialis and is also available as a generic medicine at lower cost.

Tadalafil is available in two forms: on-demand tablets (10mg or 20mg taken at least 30 minutes before sex, with effects lasting up to 36 hours) and daily tablets (2.5mg or 5mg taken once a day) [4]. Unlike some other ED treatments, tadalafil's long duration means you don't need to time it as precisely before sexual activity. However, you still need sexual stimulation for it to work—it won't cause an automatic erection [1][4].

At Cured Pharmacy, tadalafil is available after an online consultation reviewed by a UK prescriber. Generic tadalafil starts from £7.95, or £6.36 for your first order with code Ednew. All PDE5 inhibitors require a prescription because they can interact with other medicines and are not suitable for everyone [2][4].

What is selegiline and why is it prescribed?

Selegiline is a prescription medicine used to treat Parkinson's disease, a progressive neurological condition that affects movement. It works by inhibiting an enzyme called monoamine oxidase type B (MAO-B), which breaks down dopamine in the brain. By blocking this enzyme, selegiline helps increase dopamine levels, improving symptoms such as tremor, stiffness, and slow movement [12].

Selegiline is usually prescribed alongside levodopa, another Parkinson's medicine, to enhance its effects and reduce motor fluctuations. It is typically taken once or twice daily, depending on the formulation. Common brand names in the UK include Eldepryl and Zelapar [12].

Parkinson's disease itself can contribute to erectile dysfunction, both through the disease process and as a side effect of some treatments. Many men with Parkinson's seek ED treatment to maintain quality of life and intimate relationships. It's important that your prescriber knows about all your Parkinson's medications, including selegiline, before prescribing tadalafil or any other ED treatment [1][2].

How Parkinson's disease affects erectile function

Erectile dysfunction is common in men with Parkinson's disease, affecting up to 60–80% of patients. The condition can damage the nerves and blood vessels involved in erections, and some Parkinson's medications may worsen ED as a side effect. Depression and anxiety, which often accompany Parkinson's, can also contribute [1][10]. Treating ED in men with Parkinson's requires careful consideration of all current medicines and overall health, which is why a thorough consultation is essential before starting any PDE5 inhibitor.

When to get urgent help

• An erection lasting more than four hours (priapism)—go to A&E immediately
• Chest pain during or after sex—stop activity, sit down, and call 999 if it doesn't resolve quickly
• Sudden loss of vision or hearing—seek same-day medical advice
• Severe dizziness, fainting, or feeling very unwell—call 111 or see your GP urgently
• Allergic reaction (rash, swelling of face or throat, difficulty breathing)—call 999

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

Is there an interaction between tadalafil and selegiline?

No major direct interaction between tadalafil and selegiline is commonly reported in clinical practice or standard drug interaction databases [2][3][4]. Selegiline is a selective MAO-B inhibitor at standard doses, and tadalafil is a PDE5 inhibitor—they work through different mechanisms and do not directly interfere with each other's metabolism or action.

However, both medicines can affect blood pressure. Tadalafil causes mild blood vessel relaxation, which can lower blood pressure slightly, and some people taking selegiline may experience low blood pressure (hypotension) or dizziness, particularly when standing up [4][12]. When taken together, there is a theoretical risk that these effects could add up, leading to dizziness or light-headedness in some men.

Your prescriber will assess your individual situation during the online consultation. They will review your blood pressure, other medications (especially any blood-pressure-lowering medicines), and overall cardiovascular health. If you are stable on selegiline and have no significant blood pressure problems, tadalafil is usually considered safe to use [2][4]. Always declare selegiline and all other medicines, including over-the-counter products and supplements, during your consultation.

What your prescriber checks before approving tadalafil and selegiline together

During your online consultation at Cured Pharmacy, the prescriber will ask detailed questions to ensure tadalafil is safe for you. They will check your current blood pressure, any history of heart disease, stroke, or other cardiovascular conditions, and whether you take any medicines that are known to interact dangerously with tadalafil—such as nitrates (GTN spray, isosorbide), nicorandil, riociguat, or recreational drugs called poppers [2][3][4].

The prescriber will specifically review your Parkinson's medications, including selegiline, levodopa, dopamine agonists, and any others. They will also ask about other medicines that can affect blood pressure, such as alpha-blockers (e.g. tamsulosin, doxazosin), other blood-pressure tablets, and medicines that affect how tadalafil is broken down in the body (such as some antibiotics and antifungals) [2][4].

If you are taking selegiline and your blood pressure is stable, the prescriber will usually start you on the lowest effective dose of tadalafil (often 10mg on-demand or 2.5mg daily) to minimise any risk of dizziness or low blood pressure. They may advise you to take the first dose at a time when you can sit or lie down if you feel dizzy, and to avoid sudden changes in posture [4]. If you have any concerns or experience side effects, you can contact the pharmacy team for advice at any time.

Medicines that must never be taken with tadalafil

Do not take tadalafil if you use nitrates (GTN spray, isosorbide mononitrate or dinitrate tablets), nicorandil, riociguat, or recreational drugs called poppers (amyl or alkyl nitrites). Combining these with any PDE5 inhibitor, including tadalafil, can cause a dangerous and potentially life-threatening drop in blood pressure [3][4]. You must also not take tadalafil alongside another PDE5 inhibitor such as sildenafil (Viagra), vardenafil (Levitra), or avanafil (Spedra). Always tell your prescriber about every medicine you take, including those bought over the counter or online.

At a glance

Practical advice for taking tadalafil and selegiline safely

If your prescriber approves tadalafil while you are taking selegiline, follow their dosing instructions carefully. Take tadalafil exactly as prescribed—do not take more than one dose in 24 hours if using on-demand tablets, and do not exceed the daily dose if using the daily formulation [4]. Swallow the tablet whole with water; you can take it with or without food, although a very heavy or high-fat meal may delay how quickly it works.

Be aware of how you feel after taking the first dose. Sit or lie down if you experience dizziness or light-headedness, and avoid driving or operating machinery until you know how the medicine affects you. Stand up slowly from sitting or lying positions to reduce the risk of a sudden drop in blood pressure [4]. Avoid drinking large amounts of alcohol, as this can make ED worse and increase the risk of dizziness and low blood pressure.

Continue taking selegiline and all your other prescribed medicines as directed by your doctor—do not stop or change any medicine without medical advice. If you develop any new symptoms, such as persistent dizziness, fainting, chest pain during sex, or an erection lasting more than four hours, seek urgent medical help [1][4]. Keep all your medicines in their original packaging, store them safely, and check the expiry dates regularly.

Other ED treatments and alternatives for men taking selegiline

If tadalafil is not suitable or you prefer a different option, other PDE5 inhibitors are available, including sildenafil (Viagra), vardenafil (Levitra), and avanafil (Spedra). The same interaction considerations apply: no major direct interaction with selegiline is commonly reported, but your prescriber will assess your blood pressure and overall health before prescribing any PDE5 inhibitor [2][3][5][6].

Sildenafil is taken about one hour before sex and lasts for around four to six hours; it is available from £0.45 per tablet (£0.36 with code Ednew for your first order). Vardenafil works in 25–60 minutes and is priced at £16.95 (£13.56 with code Ednew). Avanafil (Spedra) is the fastest-acting, working in 15–30 minutes, and costs £20.95 (£16.76 with code Ednew) [3][5][6][11]. Your prescriber will help you choose the most suitable option based on your lifestyle, preferences, and medical history.

If PDE5 inhibitors are not suitable, other treatments include Vitaros (alprostadil cream applied to the tip of the penis) and Caverject (alprostadil injection), both of which are prescription-only [7]. Vacuum erection devices and psychological therapies such as cognitive behavioural therapy (CBT) or sex therapy can also be helpful, particularly if anxiety or relationship issues contribute to ED [1][2]. Always discuss new or worsening ED with your GP, as it can be an early warning sign of heart disease or diabetes.

When to see your GP about erectile dysfunction

If you have new or worsening erectile dysfunction, make an appointment with your GP. ED can be an early sign of cardiovascular disease, diabetes, or other health conditions that need investigation and treatment [1][2]. Your GP can check your blood pressure, blood sugar, cholesterol, and hormone levels, and review all your medicines to identify any that might be contributing to the problem. They can also refer you to a specialist if needed and discuss the full range of treatment options available on the NHS and privately.

In summary

• No major direct interaction between tadalafil and selegiline is commonly reported in clinical practice.
• Both medicines can affect blood pressure, so your prescriber will assess this carefully before approving treatment.
• Never take tadalafil with nitrates, nicorandil, riociguat, or poppers—this combination is dangerous.
• Declare all your medicines, including selegiline and other Parkinson's treatments, during your online consultation.
• Watch for dizziness or light-headedness; sit or lie down if needed and stand up slowly.

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