Tadalafil and Safinamide: Can They Be Taken Together?

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Tadalafil and Safinamide: Understanding the Interaction

Published: 25 October 2026

If you're taking safinamide for Parkinson's disease and considering tadalafil for erectile dysfunction, you may wonder whether tadalafil and safinamide can be taken together safely. The good news is that no major direct interaction between these two medicines is commonly reported in standard references, but your prescriber will still need to review your full medication list and health history during consultation. This page explains what each medicine does, what checks are needed, and the practical steps to use tadalafil safely alongside safinamide.

What is tadalafil and safinamide used for?

Tadalafil is a phosphodiesterase type 5 (PDE5) inhibitor licensed in the UK to treat erectile dysfunction (ED) and, in some cases, benign prostatic hyperplasia [4]. It works by relaxing blood vessels in the penis, allowing increased blood flow when you are sexually stimulated. 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 option (2.5 mg or 5 mg) [4]. It is the active ingredient in branded Cialis and generic versions.

Safinamide is a monoamine oxidase B (MAO-B) inhibitor used as an add-on treatment for Parkinson's disease in adults whose symptoms are not fully controlled by levodopa alone or in combination with other Parkinson's medicines [12]. It works by blocking the breakdown of dopamine in the brain, helping to improve motor symptoms and reduce 'off' periods. Safinamide is typically taken once daily as a 50 mg or 100 mg tablet.

Because safinamide affects brain chemistry and tadalafil affects blood flow, they work on different systems in the body. However, any time you take more than one medicine, your prescriber needs to check for potential interactions, overlapping side effects, and whether your overall health makes the combination suitable.

Is there an interaction between tadalafil and safinamide?

No major direct pharmacological interaction between tadalafil and safinamide is commonly reported in standard UK references such as the British National Formulary or Summaries of Product Characteristics [4][12]. This means that the two medicines do not significantly alter each other's levels in the blood or directly interfere with each other's mechanism of action in a way that would make the combination unsafe for most people.

However, 'no major interaction reported' does not mean the combination is automatically suitable for everyone. Both medicines can have side effects that may overlap or add up. For example, tadalafil can cause dizziness or a drop in blood pressure, particularly when you first stand up [4]. Safinamide can also cause dizziness, and some people with Parkinson's disease may already have blood pressure changes related to their condition or other medications. Your prescriber will assess whether these effects could be a concern for you personally.

It is also important to remember that safinamide is an MAO-B inhibitor. While it is selective for MAO-B at the licensed doses, high doses or interactions with certain other medicines (such as other antidepressants or sympathomimetics) can cause serious problems. Tadalafil is not known to interact with MAO-B inhibitors in this way, but your prescriber will review your full medication list to ensure there are no other medicines that could pose a risk when combined with safinamide.

Why your prescriber reviews every medicine

Even when no major interaction is listed, your prescriber must check your complete medical history and all current medicines during the online consultation. This includes prescription medicines, over-the-counter products, herbal supplements, and recreational substances. For example, if you are taking other medicines for Parkinson's disease (such as levodopa, entacapone, or dopamine agonists), blood pressure tablets, or antidepressants, these may influence whether tadalafil is suitable or what dose is safest. Never assume a combination is safe without a clinical review, and never stop or change a prescribed medicine without advice from your doctor or pharmacist.

What your prescriber checks before prescribing tadalafil with safinamide

During your online consultation at Cured Pharmacy, the prescriber will ask about your current medicines, including safinamide, and review your medical history. They will check for any conditions or other medicines that could make tadalafil unsafe. For example, tadalafil must never be taken with nitrates (such as GTN spray or isosorbide mononitrate), nicorandil, riociguat, or recreational drugs known as 'poppers' (amyl or alkyl nitrites), because the combination can cause a dangerous drop in blood pressure [4]. If you take any of these, do not take tadalafil.

Your prescriber will also check whether you take alpha-blockers (such as tamsulosin, doxazosin, or alfuzosin) for prostate symptoms or high blood pressure. These medicines can interact with tadalafil, increasing the risk of dizziness or low blood pressure. If you are stable on an alpha-blocker, your prescriber may start you on the lowest dose of tadalafil and advise you to take it at a different time of day [4]. Similarly, if you take other blood-pressure medicines, the prescriber will assess whether the combination is manageable.

The prescriber will also ask about your heart health. Tadalafil is not suitable if sexual activity is inadvisable—for example, if you have had a recent heart attack or stroke, unstable angina, or severe heart failure [4]. They will check whether you have ever had sudden vision loss (a rare condition called non-arteritic anterior ischaemic optic neuropathy, or NAION) or certain inherited retinal disorders, as these are contraindications. Finally, they will review any other medicines that could affect how tadalafil is broken down in your body, such as potent CYP3A4 inhibitors (for example, ritonavir, ketoconazole, or clarithromycin), which can raise tadalafil levels and require dose adjustments [4].

Practical advice for taking tadalafil and safinamide together

If your prescriber approves tadalafil for you, take it exactly as directed. For on-demand tadalafil (10 mg or 20 mg), take one tablet at least 30 minutes before you plan to have sex; the effect can last up to 36 hours, so you should 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, regardless of when you plan to have sex. Tadalafil requires sexual stimulation to work—it will not cause an erection on its own.

Continue taking safinamide as prescribed by your doctor, usually once daily in the morning. Do not stop or change the dose without medical advice. If you experience new or worsening dizziness, light-headedness, or fainting after starting tadalafil, sit or lie down and contact your GP or pharmacist. These symptoms may indicate low blood pressure, which can be more noticeable when you stand up quickly. Avoid heavy alcohol while taking tadalafil, as it can worsen ED, increase the risk of side effects such as dizziness and headache, and add to the blood-pressure-lowering effect [4].

Do not take grapefruit juice with tadalafil, as it can raise the level of the medicine in your blood. If you develop any new symptoms or your Parkinson's symptoms change after starting tadalafil, speak to your doctor. Keep all your medicines in their original packaging, store them as directed, and never share them with others. If you have any questions or concerns, contact the Cured Pharmacy team or your GP for advice.

When to seek urgent help

Seek immediate medical help if you experience an erection lasting more than four hours (priapism), as this requires urgent treatment to prevent permanent damage [4]. Call 999 or go to A&E if you have sudden loss of vision or hearing, or chest pain during or after sex. If you feel very dizzy, faint, or unwell after taking tadalafil, especially if you also take other medicines that lower blood pressure, seek same-day medical advice. Always carry a list of your current medicines (including safinamide and tadalafil) so that healthcare professionals can review them in an emergency.

Other medicines and tadalafil: what you need to know

In addition to safinamide, you may be taking other medicines for Parkinson's disease, such as levodopa, entacapone, rasagiline, or dopamine agonists (for example, pramipexole or ropinirole). No major interactions between these Parkinson's medicines and tadalafil are commonly reported, but your prescriber will review each one to ensure the combination is safe for you. Some Parkinson's medicines can cause low blood pressure or dizziness, which may add to the effects of tadalafil, so your prescriber may start you on a lower dose or advise you to monitor for symptoms.

If you take antidepressants, blood thinners, or medicines for other long-term conditions, declare them during your consultation. For example, potent CYP3A4 inhibitors (such as ritonavir, used in some HIV treatments, or ketoconazole, an antifungal) can raise tadalafil levels, requiring a lower dose [4]. CYP3A4 inducers (such as rifampicin, carbamazepine, phenytoin, or St John's wort) can reduce tadalafil's effectiveness. Your prescriber will check the Summary of Product Characteristics for any medicine you take to ensure the combination is appropriate.

Never take tadalafil with another PDE5 inhibitor (such as sildenafil, vardenafil, or avanafil) or with nitrates, nicorandil, riociguat, or poppers. These combinations can cause a dangerous drop in blood pressure and are contraindicated [4]. If you are unsure whether any of your medicines interact with tadalafil, ask your prescriber or pharmacist—do not guess or rely on information from non-medical sources.

How to access tadalafil safely at Cured Pharmacy

Tadalafil is a prescription-only medicine in the UK, which means it can only be supplied after a clinical assessment by a UK-registered prescriber [4]. At Cured Pharmacy, you start by completing a short online consultation that asks about your health, current medicines (including safinamide), and any conditions that might make tadalafil unsuitable. A UK prescriber reviews your answers and, if appropriate, approves your order. Your medicine is then dispensed by our GPhC-registered pharmacy and delivered discreetly to your door.

We offer a range of tadalafil options to suit different needs and budgets. Generic tadalafil is available from £7.95 for on-demand tablets (first order with code Ednew: £6.36), and branded Cialis from £12.00 (first order with code Ednew: £9.60). Tadalafil 20 mg (Teva) is £9.99 (first order with code Ednew: £7.99), and Avarante (tadalafil) 10 mg is £11.49 (first order with code Ednew: £9.19). All prices include the consultation, prescription, and delivery. If tadalafil is not suitable for you, the prescriber may suggest an alternative PDE5 inhibitor, such as sildenafil, vardenafil, or avanafil, depending on your circumstances.

If you experience new erectile dysfunction or if your symptoms have changed, see your GP for a face-to-face assessment. ED can be an early sign of cardiovascular disease or diabetes, and it is important to identify and treat any underlying causes [1][2]. Online services like Cured Pharmacy are designed to provide convenient access to treatment once a diagnosis has been made and your doctor has confirmed that ED medicines are appropriate for you. If you have any questions about tadalafil and safinamide or your treatment, our pharmacy team is here to help.

Why choose Cured Pharmacy?

Cured Pharmacy is a GPhC-registered online pharmacy (GPhC 9012511) with a team of experienced UK pharmacists and prescribers. We offer clear, honest advice, discreet packaging, and fast delivery across the UK. Every consultation is reviewed by a qualified prescriber, and our pharmacy team is available to answer your questions by phone, email, or live chat. We never compromise on safety or quality, and we are committed to helping you access the treatment you need with confidence and dignity.

Scientific References

1. NHS. (n.d.). Erectile dysfunction (impotence). NHS website. https://www.nhs.uk/conditions/erection-problems-erectile-dysfunction/ [accessed 25 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 25 October 2026]
3. Joint Formulary Committee. (n.d.). Tadalafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/tadalafil/ [accessed 25 October 2026]
4. Electronic Medicines Compendium. (n.d.). Summaries of Product Characteristics and Patient Information Leaflets. https://www.medicines.org.uk/emc/ [accessed 25 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.