Tadalafil and Everolimus: Can They Be Taken Together?

Tadalafil and Everolimus: Understanding the Interaction

Published: 20 October 2026

If you're taking everolimus and considering tadalafil for erectile dysfunction, it's important to understand how tadalafil and everolimus interact. Everolimus is an immunosuppressant and cancer medicine that can significantly raise the levels of tadalafil in your bloodstream, potentially increasing the risk of side effects. This page explains the mechanism behind this interaction, what your prescriber will check during your consultation, and the practical steps that keep you safe.

What Is Tadalafil and How Does It Work?

Tadalafil is a prescription medicine used to treat erectile dysfunction (ED). 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 [3][4]. Tadalafil does not cause an erection on its own—sexual stimulation is still needed.

Tadalafil is available in two 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 tablets (2.5mg or 5mg) taken once a day at the same time [4]. The longer duration of action is why tadalafil is sometimes called 'the weekend pill'. It is the generic version of Cialis and is widely prescribed for men who find it difficult to get or keep an erection firm enough for sex [1][2].

Common side effects include headache, indigestion, back pain, muscle aches, flushing, and a stuffy or runny nose [4]. Most side effects are mild and temporary. However, certain medicines and health conditions can make tadalafil unsuitable or require dose adjustments, which is why a prescriber consultation is essential before starting treatment.

What Is Everolimus and Why Is It Prescribed?

Everolimus is a prescription medicine used in two main situations: to prevent organ rejection after a kidney or heart transplant (as an immunosuppressant), and to treat certain types of cancer, including breast cancer, kidney cancer, and some brain tumours [12]. It works by blocking a protein called mTOR, which helps control cell growth and the immune response.

Because everolimus affects the immune system and is used in serious conditions, it is carefully monitored by specialist doctors. Patients taking everolimus usually have regular blood tests to check drug levels and organ function. The medicine can cause side effects such as mouth ulcers, infections, tiredness, high blood sugar, and changes in blood counts [12].

Everolimus is also a potent inhibitor of an enzyme system in the liver called CYP3A4. This enzyme is responsible for breaking down many other medicines, including tadalafil. When everolimus blocks CYP3A4, medicines that rely on this enzyme for elimination can build up in the body, leading to higher blood levels and a greater risk of side effects. This is the key reason why the interaction between tadalafil and everolimus matters and must be managed carefully by your prescriber.

How Do Tadalafil and Everolimus Interact?

The interaction between tadalafil and everolimus occurs because everolimus is a potent CYP3A4 inhibitor. Tadalafil is broken down (metabolised) in the liver mainly by the CYP3A4 enzyme [4]. When everolimus blocks this enzyme, tadalafil is cleared from your body more slowly, which means blood levels of tadalafil can become higher than usual and stay elevated for longer.

Higher tadalafil levels increase the likelihood and severity of side effects, particularly low blood pressure (hypotension), dizziness, headache, and visual disturbances [4]. In some cases, this can lead to fainting or falls, especially if you are also taking other medicines that lower blood pressure. The interaction is well-recognised in prescribing guidelines, and dose adjustments are recommended when these medicines are used together [4][12].

It is important to understand that this interaction does not mean tadalafil and everolimus cannot be taken together—many patients do use both medicines safely. However, your prescriber must know you are taking everolimus so they can start you on a lower dose of tadalafil and monitor you closely. Never start, stop, or change the dose of either medicine without consulting your doctor or pharmacist.

The Mechanism in Plain English

Think of CYP3A4 as a waste-disposal system in your liver that clears away tadalafil after it has done its job. Everolimus slows down this disposal system, so tadalafil stays in your bloodstream longer and at higher concentrations. This is similar to what happens when a drain is partially blocked—water (or in this case, the medicine) takes longer to clear away. The result is that the effects and side effects of tadalafil are stronger and last longer than they would without everolimus.

What Your Prescriber Will Check During Your Consultation

When you request tadalafil through an online consultation at Cured Pharmacy, you will be asked to list all your current medicines, including everolimus. A UK-registered prescriber will review your medical history, current treatments, and any other health conditions before deciding whether tadalafil is safe and appropriate for you [2][4].

If you are taking everolimus, your prescriber will typically recommend starting tadalafil at a reduced dose—often 10mg on-demand rather than 20mg, or a lower daily dose if daily treatment is preferred [4]. They will also check your blood pressure, heart health, and whether you are taking any other medicines that could interact, such as nitrates (which are an absolute contraindication with tadalafil), alpha-blockers, or other blood-pressure medicines [3][4].

Your prescriber will also ask about your kidney and liver function, as both organs play a role in clearing tadalafil from your body. If you have moderate to severe liver or kidney impairment in addition to taking everolimus, further dose reductions or alternative treatments may be necessary [4]. The consultation ensures that the benefits of treatment outweigh the risks and that you are given clear instructions on how to take tadalafil safely alongside your other medicines.

Practical Advice for Taking Tadalafil and Everolimus Together

If your prescriber approves tadalafil while you are on everolimus, follow their dosing instructions exactly. Do not take more than the prescribed dose, and do not take tadalafil more often than once a day if using the on-demand form [4]. Taking extra tablets will not improve your erection but will increase the risk of side effects such as dizziness, headache, and dangerously low blood pressure.

Be aware of how you feel after taking tadalafil, especially the first few times. Sit or lie down if you feel dizzy or light-headed, and avoid driving or operating machinery until you know how the medicine affects you. Avoid drinking large amounts of alcohol, as this can add to the blood-pressure-lowering effect and make side effects worse [4]. Grapefruit juice should also be avoided, as it can further increase tadalafil levels in your blood.

Keep both your cancer specialist or transplant team and your GP informed that you are using tadalafil. If you experience side effects such as severe headache, chest pain, prolonged erection (lasting more than four hours), sudden vision or hearing loss, or fainting, seek medical help immediately [4]. Do not stop taking everolimus without your specialist's advice, as this could have serious consequences for your underlying condition. Always carry an up-to-date list of all your medicines, including over-the-counter products and supplements, and show it to any healthcare professional you see.

Tips for Managing Your Medicines

Use a pill organiser or set reminders on your phone to help you take everolimus and tadalafil at the right times. If you are on daily tadalafil, take it at a consistent time each day, separate from your everolimus dose if possible, to help you remember both. Keep a diary of any side effects or changes in how you feel, and share this with your prescriber at follow-up. Good communication between you, your GP, your specialist, and your pharmacist is key to safe and effective treatment.

Other Medicines and Conditions to Be Aware Of

In addition to everolimus, several other medicines can interact with tadalafil. Never take tadalafil with nitrates (such as GTN spray, isosorbide mononitrate, or isosorbide dinitrate), nicorandil, riociguat, or recreational drugs known as 'poppers' (amyl or alkyl nitrites), as the combination can cause a dangerous drop in blood pressure [3][4]. Do not take tadalafil alongside another PDE5 inhibitor such as sildenafil, vardenafil, or avanafil.

If you take alpha-blockers for prostate problems or high blood pressure (such as doxazosin, tamsulosin, or alfuzosin), tell your prescriber, as these can also lower blood pressure when combined with tadalafil [4]. You should be stable on your alpha-blocker before starting tadalafil, and your prescriber will usually recommend the lowest effective dose of the ED medicine. Other potent CYP3A4 inhibitors—such as ritonavir, cobicistat (found in some HIV medicines), ketoconazole, itraconazole, and clarithromycin—can have a similar effect to everolimus and require dose adjustments [4].

Tadalafil is not suitable if you have recently had a heart attack or stroke, have unstable angina, severe heart failure, very low blood pressure, or a history of non-arteritic anterior ischaemic optic neuropathy (NAION), a rare cause of sudden vision loss [4]. Your prescriber will assess your cardiovascular health as part of the consultation. If you have any concerns about whether tadalafil is right for you, discuss them openly during your consultation—there is no question too small when it comes to your safety.

When to Seek Further Advice

If you start a new medicine, including antibiotics or antifungals, while taking tadalafil and everolimus, check with your pharmacist or doctor whether it is safe to continue. Some short-term medicines can also affect CYP3A4 and temporarily increase tadalafil levels. If your everolimus dose changes or you experience new side effects from either medicine, contact your prescriber for advice. Regular monitoring and open communication help ensure your treatment remains safe and effective.

Scientific References

1. NHS. (n.d.). Erectile dysfunction (impotence). NHS website. https://www.nhs.uk/conditions/erection-problems-erectile-dysfunction/ [accessed 20 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 20 October 2026]
3. Joint Formulary Committee. (n.d.). Sildenafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/sildenafil/ [accessed 20 October 2026]
4. Joint Formulary Committee. (n.d.). Tadalafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/tadalafil/ [accessed 20 October 2026]
5. Electronic Medicines Compendium. (n.d.). Summaries of Product Characteristics and Patient Information Leaflets. https://www.medicines.org.uk/emc/ [accessed 20 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.

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