Tadalafil and Ranolazine: Can They Be Taken Together?

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Tadalafil and Ranolazine: Understanding the Interaction

Published: 25 October 2026

Many men taking ranolazine for angina wonder whether tadalafil and ranolazine can be taken together safely. Ranolazine (Ranexa) is a medicine used to treat chronic stable angina, while tadalafil (Cialis) is a PDE5 inhibitor used to treat erectile dysfunction. Understanding how these medicines interact is important for your safety and effective treatment.

What is tadalafil and ranolazine used for?

Tadalafil is a phosphodiesterase type 5 (PDE5) inhibitor licensed in the UK to treat erectile dysfunction [4]. It works by relaxing blood vessels in the penis, allowing increased blood flow when you are sexually aroused. Tadalafil is available as on-demand tablets (10mg or 20mg taken at least 30 minutes before sexual activity, with effects lasting up to 36 hours) or as a daily low-dose option (2.5mg or 5mg). All PDE5 inhibitors require sexual stimulation to work [1].

Ranolazine (brand name Ranexa) is an anti-anginal medicine used to treat chronic stable angina in adults whose symptoms are not adequately controlled by, or who cannot tolerate, first-line anti-anginal therapies such as beta-blockers or calcium channel blockers [12]. It works by affecting sodium channels in heart muscle cells, helping to reduce the frequency of angina attacks. Ranolazine does not lower blood pressure in the same way as many other heart medicines, but it is metabolised by the same liver enzyme system (CYP3A4) as tadalafil.

Can you take tadalafil and ranolazine together?

Tadalafil and ranolazine can generally be taken together, but caution is needed because ranolazine is a moderate inhibitor of the liver enzyme CYP3A4, which breaks down tadalafil in the body [4][12]. When ranolazine slows down this enzyme, tadalafil levels in your blood can rise, potentially increasing the risk of side effects such as headache, indigestion, back pain, flushing, or dizziness.

This interaction is not an absolute contraindication (unlike the dangerous combination of tadalafil with nitrates, nicorandil, or riociguat, which must never be taken together). However, your prescriber will need to consider your ranolazine dose and may adjust your tadalafil dose accordingly. The maximum recommended dose of tadalafil when taken with a moderate CYP3A4 inhibitor like ranolazine is usually 10mg within a 72-hour period for on-demand use [4]. Your prescriber will review your full medication list during the online consultation to ensure safe prescribing.

How the interaction works

Both tadalafil and ranolazine are broken down (metabolised) in the liver by an enzyme called CYP3A4. Ranolazine partially blocks this enzyme, meaning tadalafil stays in your system for longer and at higher levels than it would on its own. This can make the effects of tadalafil stronger and last longer, which may be helpful for erectile function but also increases the chance of side effects. Your prescriber takes this into account when deciding on the safest starting dose for you.

What your prescriber checks before prescribing tadalafil with ranolazine

During your online consultation at Cured Pharmacy, the UK-registered prescriber will ask about all your current medicines, including ranolazine, to assess whether tadalafil is safe and suitable for you. They will check the dose of ranolazine you are taking, how well controlled your angina is, and whether you are taking any other medicines that might interact (such as other CYP3A4 inhibitors or medicines that lower blood pressure) [2][4].

The prescriber will also confirm that you are not taking any medicines that are absolutely contraindicated with tadalafil, such as nitrates (GTN spray, isosorbide mononitrate or dinitrate), nicorandil, riociguat, or another PDE5 inhibitor. They will review your cardiovascular health to ensure that sexual activity is safe for you, particularly if you have a history of heart attack, stroke, unstable angina, or severe heart failure [1][4]. If tadalafil is appropriate, they may start you on a lower dose (such as 10mg on-demand) to minimise the risk of side effects.

Practical advice for taking tadalafil and ranolazine safely

If you are prescribed tadalafil while taking ranolazine, follow your prescriber's instructions carefully. Take tadalafil exactly as directed—do not exceed the recommended dose or take it more often than advised. For on-demand tadalafil, take the tablet at least 30 minutes before sexual activity; the effect can last up to 36 hours, so you should not take more than one dose in that period [4].

Be aware of common side effects such as headache, indigestion, flushing, nasal congestion, or dizziness, which may be more noticeable because of the interaction with ranolazine. If you experience severe or persistent side effects, contact your GP or pharmacist. Avoid drinking large amounts of alcohol, as this can worsen erectile dysfunction and add to the blood-pressure-lowering effect of tadalafil, increasing the risk of dizziness or fainting [1][4].

Do not stop or change your ranolazine or any other prescribed medicine without consulting your doctor. If you are prescribed a new medicine by another healthcare professional, always tell them you are taking both ranolazine and tadalafil so they can check for further interactions. Keep all your medicines in their original packaging and store them safely out of reach of children.

When to seek medical advice

Seek urgent medical help if you experience chest pain during sexual activity, an erection lasting more than four hours (priapism), sudden loss of vision in one or both eyes, or sudden decrease or loss of hearing [4]. These are rare but serious side effects that require immediate attention. If you develop new or worsening angina symptoms, or if your erectile dysfunction does not improve, speak to your GP, as this may indicate that your treatment needs reviewing.

Other medicines that interact with tadalafil in a similar way

Ranolazine is not the only medicine that can raise tadalafil levels in the blood. Other moderate or potent inhibitors of the CYP3A4 enzyme include certain antibiotics (such as clarithromycin and erythromycin), antifungals (ketoconazole, itraconazole), HIV medicines (ritonavir, cobicistat), and some medicines used to treat COVID-19 (such as Paxlovid, which contains ritonavir) [4][12].

If you are taking a potent CYP3A4 inhibitor, the dose restrictions for tadalafil are stricter: for on-demand use, the maximum dose is usually 10mg within 72 hours, and daily tadalafil may not be recommended at all. Your prescriber will check the specific interaction for each medicine you are taking. Conversely, medicines that speed up the CYP3A4 enzyme (such as rifampicin, carbamazepine, phenytoin, or St John's wort) can make tadalafil less effective by breaking it down more quickly [4].

Grapefruit juice can also inhibit CYP3A4 and raise tadalafil levels, so it is best to avoid drinking large amounts of grapefruit juice while taking tadalafil. Always declare every medicine, supplement, and herbal remedy you are taking during your consultation, even if you think it is unrelated, so your prescriber can give you the safest advice.

Accessing tadalafil and ranolazine treatment through Cured Pharmacy

Cured Pharmacy is a GPhC-registered online pharmacy (GPhC 9012511) offering convenient access to erectile dysfunction treatments after a clinical assessment by a UK-registered prescriber. If you are taking ranolazine and would like to explore treatment for erectile dysfunction, you can complete a short online consultation that asks about your medical history, current medicines, and cardiovascular health [2].

The prescriber will review your answers and, if tadalafil is safe and suitable for you, issue a prescription. Your medicine is then dispensed by our UK pharmacy and delivered discreetly to your door. We offer a range of tadalafil options, including generic tadalafil and branded Cialis, as well as other PDE5 inhibitors such as sildenafil (Viagra), vardenafil (Levitra), and avanafil (Spedra) if an alternative is more appropriate for you [3][4][5][6].

Remember that erectile dysfunction can be an early warning sign of cardiovascular disease or diabetes, so if you have not already done so, it is important to see your GP for a full health check [1][2]. Treating the underlying cause—such as improving blood sugar control, managing blood pressure, or stopping smoking—can improve erectile function as well as your overall health. Our service complements, but does not replace, the care provided by your GP.

Why choose Cured Pharmacy?

Cured Pharmacy combines clinical expertise with convenience. Every prescription is reviewed by a UK-registered prescriber who takes your full medical history and current medicines into account, including interactions like tadalafil and ranolazine. Our service is confidential, discreet, and designed to make accessing effective ED treatment straightforward. If you have any questions about your treatment, our pharmacist-led team is here to help.

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.). Sildenafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/sildenafil/ [accessed 25 October 2026]
4. Joint Formulary Committee. (n.d.). Tadalafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/tadalafil/ [accessed 25 October 2026]
5. Joint Formulary Committee. (n.d.). Vardenafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/vardenafil/ [accessed 25 October 2026]
6. Joint Formulary Committee. (n.d.). Avanafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/avanafil/ [accessed 25 October 2026]
7. 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.