Tadalafil and Flupentixol: Can They Be Taken Together?

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Tadalafil and Flupentixol: What You Need to Know About This Combination

Published: 21 October 2026

If you're prescribed flupentixol and considering tadalafil for erectile dysfunction, you may be wondering whether tadalafil and flupentixol can be taken together safely. The good news is that no major direct interaction between these two medicines is commonly reported in clinical practice, but your prescriber will still need to review your full medical history and current medications during a consultation. This page explains what each medicine does, how they might affect each other, and the practical steps to ensure safe, effective treatment.

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 phosphodiesterase type 5 (PDE5) inhibitors, which work by relaxing the blood vessels in the penis, allowing more blood to flow in when you are sexually aroused [3][4]. Tadalafil is the active ingredient in Cialis and is available in both on-demand doses (10 mg or 20 mg taken at least 30 minutes before sexual activity) and daily low doses (2.5 mg or 5 mg taken once a day). One of tadalafil's key advantages is its long duration of action—effects can last up to 36 hours, earning it the nickname 'the weekend pill' [4].

Tadalafil does not cause an erection by itself; sexual stimulation is still needed. It is licensed for men aged 18 and over and is only supplied after an online or face-to-face consultation with a UK prescriber, who will check your medical history, current medicines, and whether tadalafil is suitable and safe for you [1][2].

What is flupentixol and why is it prescribed?

Flupentixol (also spelled flupenthixol) is an antipsychotic medicine used to treat schizophrenia and other psychotic disorders. It belongs to a class of medicines called typical (first-generation) antipsychotics, which work by blocking dopamine receptors in the brain, helping to reduce symptoms such as hallucinations, delusions, and agitation. Flupentixol is available in tablet form (usually taken once or twice daily) and as a long-acting depot injection given every two to four weeks.

In lower doses, flupentixol is sometimes prescribed for depression or anxiety, particularly when other treatments have not worked. Like many antipsychotic medicines, flupentixol can cause side effects including drowsiness, dizziness, weight gain, and changes in blood pressure. It is important to take flupentixol exactly as prescribed and not to stop it suddenly without medical advice, as this can lead to withdrawal symptoms or a return of the condition being treated.

Is there an interaction between tadalafil and flupentixol?

There is no well-documented direct pharmacological interaction between tadalafil and flupentixol. Neither medicine is known to significantly affect the metabolism or action of the other in the body. However, both medicines can lower blood pressure, and taking them together may add to this effect, potentially causing dizziness, light-headedness, or fainting, especially when standing up quickly [3][4]. This is not a reason to avoid the combination, but it does mean your prescriber will need to assess your individual circumstances carefully.

Flupentixol does not inhibit or induce the liver enzymes (CYP3A4) that break down tadalafil, so it should not raise or lower tadalafil levels in your blood. Equally, tadalafil does not interfere with the way flupentixol works in the brain. The main consideration is the additive effect on blood pressure and any underlying cardiovascular risk factors, which your prescriber will review during your consultation [2].

Why blood pressure matters

Tadalafil works by relaxing blood vessels, which can cause a mild drop in blood pressure—usually not a problem for most men, but it can become significant if you are also taking other medicines that lower blood pressure, such as antipsychotics like flupentixol. Your prescriber will check your blood pressure history, ask about any dizziness or fainting episodes, and may recommend starting on a lower dose of tadalafil to minimise risk. If you experience dizziness, avoid driving or operating machinery until you know how the combination affects you.

What will your prescriber check before prescribing tadalafil and flupentixol together?

When you request tadalafil through Cured Pharmacy, a UK-registered prescriber will review your online consultation to ensure it is safe for you. They will ask about all your current medicines, including flupentixol, and check for any conditions that might make tadalafil unsuitable, such as recent heart attack or stroke, severe heart failure, very low blood pressure, or a history of sudden vision loss (non-arteritic anterior ischaemic optic neuropathy, or NAION) [1][2][3]. You must declare every medicine you take, including over-the-counter products and herbal remedies, as some can interact dangerously with tadalafil.

Your prescriber will also consider your mental health condition and whether your ED might be related to flupentixol itself. Antipsychotic medicines, including flupentixol, can sometimes contribute to erectile dysfunction by affecting dopamine pathways, hormone levels, or blood flow. If this is the case, your prescriber may discuss adjusting your flupentixol dose or trying an alternative antipsychotic with your psychiatrist or GP, rather than simply adding tadalafil. Never stop or change flupentixol without medical advice, as this can be dangerous [2].

Medicines you must not take with tadalafil

Do not take tadalafil if you are using nitrates (such as GTN spray, isosorbide mononitrate, or isosorbide dinitrate), nicorandil, riociguat, or recreational drugs called 'poppers' (amyl or alkyl nitrites). The combination can cause a dangerous, life-threatening drop in blood pressure [3][4]. You must also not take tadalafil at the same time as another PDE5 inhibitor (sildenafil, vardenafil, or avanafil). Always tell your prescriber about every medicine you use, including those prescribed by different doctors or bought over the counter.

Practical advice for taking tadalafil and flupentixol safely

If your prescriber approves the combination, take each medicine exactly as directed. Tadalafil on-demand tablets (10 mg or 20 mg) should be taken at least 30 minutes before sexual activity, with effects lasting up to 36 hours; daily tadalafil (2.5 mg or 5 mg) is taken once a day at the same time, regardless of when you plan to have sex [4]. Swallow the tablet whole with water, with or without food. Flupentixol should be taken as prescribed by your psychiatrist or GP, usually once or twice daily. Do not adjust the dose or timing of either medicine without medical advice.

Avoid drinking large amounts of alcohol, as this can worsen erectile dysfunction, increase the risk of dizziness and low blood pressure, and reduce the effectiveness of tadalafil [1][3]. Grapefruit juice can raise tadalafil levels in your blood and should be avoided. If you feel dizzy or light-headed, sit or lie down until it passes, and avoid driving or using heavy machinery. Stand up slowly from sitting or lying positions to reduce the risk of fainting. If side effects are troublesome or do not settle, contact your prescriber or GP for advice.

When to seek urgent medical help with tadalafil and flupentixol

Most men tolerate tadalafil and flupentixol together without serious problems, but you should seek urgent medical help in certain situations. If you develop an erection that lasts longer than four hours (priapism), go to A&E immediately or call 999, as this can cause permanent damage to the penis if not treated quickly [3][4]. Sudden loss of vision in one or both eyes, or sudden decrease or loss of hearing (sometimes with ringing in the ears or dizziness), requires immediate medical attention, as these are rare but serious side effects of PDE5 inhibitors [3][4].

If you experience chest pain during or after sex, do not use nitrate medicines to treat it—tell the doctor or paramedic that you have taken tadalafil, as nitrates and tadalafil together can be dangerous [3]. Severe dizziness, fainting, or a very fast or irregular heartbeat should also prompt you to seek same-day medical advice. If you are unsure whether a symptom is serious, contact NHS 111 for guidance, or speak to your GP or pharmacist. Never stop taking flupentixol suddenly because of side effects; always discuss any concerns with the doctor who prescribed it.

Can flupentixol cause erectile dysfunction?

Yes, flupentixol and other antipsychotic medicines can contribute to erectile dysfunction. They may do this by blocking dopamine (which plays a role in sexual arousal), raising prolactin levels (which can lower testosterone), or affecting blood flow and blood pressure. If you think your ED started or worsened after beginning flupentixol, discuss this with your GP or psychiatrist. They may be able to adjust your dose, switch to a different antipsychotic with fewer sexual side effects, or add another treatment. Do not stop flupentixol on your own, as this can cause serious mental health problems.

Scientific References

1. NHS. (n.d.). Erectile dysfunction (impotence). NHS website. https://www.nhs.uk/conditions/erection-problems-erectile-dysfunction/ [accessed 21 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 21 October 2026]
3. Joint Formulary Committee. (n.d.). Sildenafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/sildenafil/ [accessed 21 October 2026]
4. Joint Formulary Committee. (n.d.). Tadalafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/tadalafil/ [accessed 21 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.