Tadalafil and Rasagiline: Can You Take Them Together?

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At a glance

What is tadalafil and how does it work?

Tadalafil is a prescription medicine licensed in the UK to treat erectile dysfunction (ED) in adult men [4]. It belongs to a group of medicines called phosphodiesterase type 5 (PDE5) inhibitors, which work by relaxing the blood vessels in the penis, allowing increased blood flow when you are sexually stimulated [1]. Unlike some other ED treatments, tadalafil does not cause an automatic erection—sexual arousal is still needed for it to work.

Tadalafil is available in two main forms: on-demand tablets (usually 10mg or 20mg) taken at least 30 minutes before sexual activity, with effects lasting up to 36 hours, and daily low-dose tablets (2.5mg or 5mg) taken once a day at the same time [4]. The longer duration of action has earned tadalafil the nickname 'the weekend pill'. Common brand names include Cialis, and generic versions are widely available at lower cost.

At Cured Pharmacy, all tadalafil prescriptions are issued following an online consultation reviewed by a UK-registered prescriber, who will check your suitability and any potential interactions with your current medicines.

What is rasagiline and why is it prescribed?

Rasagiline is a prescription medicine used to treat the symptoms of Parkinson's disease, a progressive neurological condition that affects movement and coordination. It belongs to a class of drugs called monoamine oxidase type B (MAO-B) inhibitors, which work by blocking the enzyme that breaks down dopamine in the brain. By preserving dopamine levels, rasagiline helps improve motor symptoms such as tremor, stiffness, and slowness of movement.

Rasagiline is usually taken once daily, either alone in early Parkinson's disease or alongside levodopa in more advanced stages. Common brand names include Azilect. Because it affects brain chemistry, rasagiline can interact with certain foods (particularly those high in tyramine, such as aged cheeses and cured meats) and other medications, so your doctor will give you specific dietary and medication advice.

Parkinson's disease itself can contribute to erectile dysfunction, both through the disease process and as a side effect of some Parkinson's medications. Many men with Parkinson's seek treatment for ED to maintain quality of life and intimate relationships, making it important to understand how ED treatments interact with Parkinson's drugs.

How Parkinson's disease affects erectile function

Parkinson's disease can affect erectile function through multiple pathways: the disease itself disrupts the nervous system signals needed for erections, dopamine imbalance affects sexual desire, and some Parkinson's medications can either worsen or occasionally improve sexual function. Depression and anxiety, which are common in Parkinson's, also contribute to ED. Discussing sexual health with your neurologist and GP is an important part of managing overall wellbeing with Parkinson's disease.

Is there an interaction between tadalafil and rasagiline?

No major direct pharmacological interaction between tadalafil and rasagiline is commonly reported in clinical practice or standard drug interaction databases. These two medicines work through completely different mechanisms in different parts of the body: tadalafil acts on blood vessels primarily in the penis, while rasagiline works on brain chemistry to preserve dopamine. Neither medicine is known to significantly affect the metabolism or action of the other.

However, this does not mean the combination is automatically suitable for everyone. Your prescriber will still need to assess your individual circumstances, including your blood pressure, heart health, other medications, and overall fitness for sexual activity [2]. Both medicines can potentially affect blood pressure—tadalafil can cause a modest drop, and rasagiline is occasionally associated with blood pressure changes—so monitoring is important, especially when starting treatment.

It's crucial to declare rasagiline (and all other medicines, including over-the-counter products and supplements) during your ED consultation. Your prescriber will check for any indirect interactions, review your cardiovascular health, and ensure that sexual activity is safe for you. Never take tadalafil or any PDE5 inhibitor if you are also using nitrates, nicorandil, riociguat, or recreational drugs called 'poppers', as these combinations can cause a dangerous drop in blood pressure [3][4].

What you need to know

• No major direct interaction between tadalafil and rasagiline is commonly reported in clinical practice.
• Your prescriber will check your blood pressure, heart health, and all medications before approving tadalafil.
• Both medicines can affect blood pressure, so monitoring for dizziness is important when starting treatment.
• Always declare rasagiline and all Parkinson's medications during your ED consultation for safe prescribing.
• Seek urgent help for erections lasting over four hours, chest pain, or sudden vision or hearing loss.

What does your prescriber check before approving tadalafil and rasagiline together?

When you request tadalafil while taking rasagiline, your prescriber will conduct a thorough assessment to ensure the treatment is safe and appropriate for you. They will review your complete medication list, including the dose and frequency of rasagiline, to check for any potential interactions or contraindications. They will ask about your Parkinson's symptoms, how well controlled they are, and whether you've experienced any side effects from rasagiline, particularly related to blood pressure.

Your cardiovascular health is a key focus: the prescriber will ask about your blood pressure readings, any history of heart disease, stroke, or chest pain, and whether you take any other blood-pressure-lowering medicines [2]. They need to confirm that you are not taking nitrates (such as GTN spray or isosorbide mononitrate), nicorandil, riociguat, or alpha-blockers like tamsulosin or doxazosin, as these require special precautions or are contraindicated with PDE5 inhibitors.

The prescriber will also assess whether sexual activity itself is advisable for you, considering your overall physical fitness and any recent cardiovascular events. They may recommend starting with a lower dose of tadalafil to see how you respond, and they will provide clear instructions on when and how to take it, what side effects to watch for, and when to seek urgent help.

Other Parkinson's medications and ED treatment

If you take other Parkinson's medications alongside rasagiline—such as levodopa, dopamine agonists (pramipexole, ropinirole), COMT inhibitors (entacapone), or amantadine—you must declare these too. Some dopamine agonists can cause low blood pressure or, rarely, compulsive behaviours including increased sexual urges. Your prescriber will consider the full picture to ensure tadalafil is safe and appropriate for your individual situation.

Practical advice for taking tadalafil and rasagiline safely

If your prescriber approves tadalafil while you're taking rasagiline, follow their instructions carefully. Take rasagiline exactly as prescribed by your neurologist or GP, at the same time each day, and do not stop or change the dose without medical advice. For on-demand tadalafil, take it at least 30 minutes before planned sexual activity; for daily tadalafil, take it at the same time every day, regardless of when you plan to have sex [4].

Monitor your blood pressure, especially when you first start tadalafil or if your rasagiline dose changes. If you feel dizzy, light-headed, or faint—particularly when standing up—sit or lie down and tell your doctor. Avoid drinking large amounts of alcohol, as this can worsen erectile dysfunction, increase the risk of side effects like dizziness and headache, and add to blood-pressure-lowering effects. Grapefruit juice can raise tadalafil levels in your blood, so it's best to avoid it.

Common side effects of tadalafil include headache, indigestion, back pain, muscle aches, flushing, and nasal congestion; these are usually mild and temporary [4]. If you experience chest pain during or after sex, do not use nitrates to treat it—seek urgent medical help and tell the healthcare team you have taken tadalafil. If you have an erection lasting more than four hours, sudden loss of vision or hearing, or severe dizziness, seek emergency help immediately.

When to get urgent help

• Erection lasting more than four hours (priapism) – go to A&E immediately
• Sudden loss of vision or hearing – seek emergency medical help
• Chest pain during or after sexual activity – call 999 and tell them you have taken tadalafil
• Severe dizziness, fainting, or very low blood pressure – seek same-day medical advice
• Allergic reaction (swelling of face, lips, tongue, or throat, difficulty breathing) – call 999

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

Alternatives to tadalafil and when to see your GP

Tadalafil is not the only option for treating erectile dysfunction. Other PDE5 inhibitors licensed in the UK include sildenafil (Viagra), vardenafil (Levitra), and avanafil (Spedra) [3][5][6]. Each has a slightly different onset and duration of action, and your prescriber can help you choose the most suitable one based on your lifestyle, other medications, and personal preference. You must never take more than one PDE5 inhibitor at the same time, as this increases the risk of serious side effects.

If oral tablets are not suitable or effective, other treatments are available, including alprostadil cream (Vitaros) applied to the tip of the penis, alprostadil injections (Caverject), vacuum erection devices, or psychological therapies such as cognitive behavioural therapy or psychosexual counselling [2][7]. Your GP or a specialist can discuss these options with you.

It's important to see your GP if you develop new or worsening erectile dysfunction, as ED can be an early warning sign of underlying health conditions such as cardiovascular disease, diabetes, or hormonal imbalances [1][10]. Your GP can investigate the cause, optimise management of any long-term conditions (including Parkinson's disease), review all your medications, and refer you to a specialist if needed. Open, honest conversations about sexual health are a normal and important part of healthcare.

How Cured Pharmacy can help

Cured Pharmacy is a GPhC-registered online pharmacy (GPhC 9012511) offering discreet, convenient access to ED treatments following a clinical consultation reviewed by a UK-registered prescriber. You can request tadalafil, sildenafil, vardenafil, or avanafil online, and your prescriber will carefully review your medical history, current medications (including rasagiline), and suitability for treatment. If approved, your medicine is dispensed by our pharmacy team and delivered discreetly to your door. We're here to support your health and wellbeing with professional, compassionate care.

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