Tadalafil and Imatinib: Can They Be Taken Together?
Learn how these medicines interact and how our UK pharmacist-led consultation ensures safe, effective ED treatment.
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Tadalafil and Imatinib: Understanding the Interaction
Published: 21 October 2026
Many men taking imatinib for cancer wonder whether tadalafil and imatinib can be used together safely for erectile dysfunction. The good news is that this combination is not contraindicated, but it does require careful prescriber review because imatinib can raise tadalafil levels in the body, potentially increasing the risk of side effects. This page explains what each medicine does, how they interact, what your prescriber will check during your consultation, and practical steps to use tadalafil safely if you are on imatinib.
Key takeaways
- Tadalafil and imatinib can be taken together, but imatinib raises tadalafil levels, so a lower starting dose is usually needed.
- Imatinib is a moderate CYP3A4 inhibitor, slowing the breakdown of tadalafil and increasing the risk of side effects.
- Always declare imatinib and all other medicines during your online consultation so the prescriber can adjust your dose safely.
- Inform your oncologist that you are using tadalafil to ensure coordinated care during cancer treatment.
- Seek urgent help if you experience chest pain during sex, an erection lasting over four hours, or sudden vision or hearing loss.
What Is Tadalafil and How Does It Work?
Tadalafil is a prescription medicine licensed in the UK to treat erectile dysfunction (ED) [4]. It belongs to a group of medicines called phosphodiesterase type 5 (PDE5) inhibitors, which work by relaxing blood vessels in the penis, allowing increased blood flow during sexual stimulation [1]. Tadalafil is the active ingredient in branded Cialis and is also available as a lower-cost generic.
Tadalafil comes in two forms: on-demand tablets (10 mg or 20 mg taken at least 30 minutes before sex, with effects lasting up to 36 hours) and daily low-dose tablets (2.5 mg or 5 mg taken once a day) [4]. Unlike some other ED treatments, tadalafil's long duration means you don't need to time it as precisely before sexual activity. However, sexual stimulation is still required for the medicine to work [1].
Common side effects include headache, indigestion, back pain, muscle aches, flushing, and nasal congestion [4]. Tadalafil is broken down in the liver by an enzyme system called CYP3A4, which is important when considering interactions with other medicines, including imatinib.
What Is Imatinib and Why Is It Prescribed?
Imatinib (brand name Glivec) is a targeted cancer medicine known as a tyrosine kinase inhibitor [12]. It is prescribed to treat certain types of leukaemia (such as chronic myeloid leukaemia) and gastrointestinal stromal tumours (GIST), among other conditions. Imatinib works by blocking specific proteins that cancer cells need to grow and divide, helping to control or slow the progression of the disease.
Because imatinib is a long-term treatment for many patients, quality of life—including sexual health—remains an important consideration. Erectile dysfunction can occur in men with cancer for many reasons: the disease itself, psychological stress, fatigue, or the effects of treatment [1]. Addressing ED with appropriate medication can be an important part of overall wellbeing during and after cancer treatment.
Imatinib is metabolised in the liver and is also a moderate inhibitor of the CYP3A4 enzyme system [12]. This means it can slow the breakdown of other medicines that rely on the same enzyme pathway, including tadalafil. Understanding this interaction is key to using both medicines safely together.
Can Cancer Treatment Cause Erectile Dysfunction?
Yes, cancer and its treatment can contribute to erectile dysfunction through several mechanisms [1]. Physical fatigue, hormonal changes, reduced blood flow, nerve damage (depending on the cancer site and treatment), and psychological factors such as anxiety and depression all play a role. If you are experiencing ED while on cancer treatment, it is important to discuss it with your oncologist or GP, as effective treatments are available and your healthcare team can tailor advice to your individual situation.
At a glance
How Do Tadalafil and Imatinib Interact?
Tadalafil and imatinib interact because imatinib inhibits the CYP3A4 enzyme that breaks down tadalafil in the liver [4][12]. When this enzyme is partially blocked, tadalafil stays in your bloodstream for longer and at higher levels than it would on its own. This is known as a pharmacokinetic interaction, and it can increase both the therapeutic effects and the risk of side effects from tadalafil.
Imatinib is classified as a moderate CYP3A4 inhibitor, not a potent one [12]. This means the interaction is clinically significant and must be managed, but it does not make the combination unsafe or contraindicated. Your prescriber will typically recommend starting tadalafil at a lower dose and monitoring your response carefully. For example, if you are taking tadalafil on-demand, a starting dose of 10 mg (rather than 20 mg) may be advised, and the maximum dose may be reduced [4].
It is essential that you declare imatinib (and all other medicines, including over-the-counter products and supplements) during your online consultation at Cured Pharmacy. Our UK-registered prescribers review every medicine you are taking to ensure tadalafil is safe and appropriate for you. Never adjust the dose of either medicine yourself without professional advice.
What Will Your Prescriber Check Before Approving Tadalafil?
During your consultation, the prescriber will review your full medical history, current medications (including imatinib), and any other health conditions [2]. They will check that you are not taking medicines that are contraindicated with tadalafil, such as nitrates (GTN spray, isosorbide mononitrate), nicorandil, riociguat, or recreational drugs known as poppers (amyl or alkyl nitrites), as these combinations can cause a dangerous drop in blood pressure [3][4].
The prescriber will also assess your cardiovascular health, as sexual activity places demands on the heart [2]. If you have had a recent heart attack or stroke, unstable angina, severe heart failure, very low blood pressure, or certain eye conditions (such as non-arteritic anterior ischaemic optic neuropathy), tadalafil may not be suitable [4]. Your oncologist's input may be sought if there are complex interactions or if your cancer treatment affects your heart or blood pressure.
Because imatinib can raise tadalafil levels, the prescriber will consider a lower starting dose and may advise you to watch for side effects such as headache, dizziness, flushing, or visual disturbances [4]. If you experience any unusual or severe symptoms, you should contact your prescriber or GP promptly. The goal is to find the lowest effective dose that improves erectile function while minimising side effects.
Do You Need Your Oncologist's Approval?
It is good practice to inform your oncologist that you are considering or using tadalafil for erectile dysfunction, especially if you are on imatinib or other cancer treatments. While the prescriber at Cured Pharmacy will review your medication list and medical history, your oncologist has the most complete picture of your cancer care and can advise on any additional considerations. Open communication between your healthcare providers ensures the safest, most coordinated care.
Declare All Your Medicines
Always list every medicine you take—prescription, over-the-counter, and supplements—during your consultation. This allows the prescriber to check for interactions, adjust your tadalafil dose safely, and ensure the best outcome for your erectile dysfunction treatment while on imatinib.
Practical Advice for Taking Tadalafil with Imatinib
If your prescriber approves tadalafil while you are on imatinib, start with the lowest recommended dose and take it exactly as directed [4]. For on-demand tadalafil, this typically means 10 mg at least 30 minutes before sexual activity, with a maximum of one dose in 24 hours. Do not take more than the prescribed dose, even if you feel the effect is not strong enough; instead, discuss this with your prescriber, who may adjust the dose if it is safe to do so.
Avoid drinking grapefruit juice while taking tadalafil, as it can further inhibit CYP3A4 and raise tadalafil levels unpredictably [4]. Limit alcohol intake, as heavy drinking can worsen erectile dysfunction and add to the blood-pressure-lowering effect of tadalafil, increasing the risk of dizziness or fainting [1][4]. Staying well hydrated, eating a balanced diet, and managing stress can all support your overall health and sexual function during cancer treatment.
Keep all your medicines in their original packaging, store them as directed, and never share prescription medicines with others. If you develop side effects such as prolonged headache, severe dizziness, chest pain during sex, or an erection lasting more than four hours (priapism), seek medical help immediately [4]. Report any new or worsening symptoms to both your prescriber and your oncologist so they can work together to adjust your treatment plan if needed.
Other ED Treatments and Alternatives
Tadalafil is one of several PDE5 inhibitors licensed in the UK for erectile dysfunction [2]. Alternatives include sildenafil (Viagra), vardenafil (Levitra), and avanafil (Spedra) [3][5][6]. All of these medicines work in a similar way and are also metabolised by CYP3A4, so the same interaction with imatinib applies: your prescriber will need to adjust the dose or choose the most appropriate option based on your individual circumstances and the severity of the interaction.
For men who cannot take PDE5 inhibitors, or for whom they are not effective, other treatments are available. These include alprostadil, which can be given as a cream applied to the urethra (Vitaros) or as an injection into the penis (Caverject) [7]. Vacuum erection devices and penile implants are non-drug options that may be considered in specialist settings [2]. Your GP or a specialist in sexual medicine can discuss the full range of treatments and refer you if needed.
At Cured Pharmacy, all PDE5 inhibitors require a prescription following an online consultation with a UK-registered prescriber. The consultation is designed to be straightforward and confidential, and our team will work with you to find the safest, most effective treatment for your situation. If you have any questions about tadalafil and imatinib or any other aspect of your ED treatment, our pharmacists are here to help.
When to See Your GP About Erectile Dysfunction
If you are experiencing erectile dysfunction for the first time, or if it is getting worse, see your GP [1][2]. ED can be an early warning sign of cardiovascular disease, diabetes, or other health conditions that need investigation and treatment. Your GP can arrange blood tests, review your medications, and refer you to a specialist if necessary. Treating the underlying cause, alongside using ED medication if appropriate, offers the best chance of long-term improvement in sexual function and overall health.
When to get urgent help
- Erection lasting more than 4 hours (priapism) – go to A&E immediately to prevent permanent damage
- Sudden loss of vision in one or both eyes – stop tadalafil and seek urgent medical attention
- Sudden decrease or loss of hearing, possibly with ringing in the ears or dizziness – stop tadalafil and see a doctor urgently
- Chest pain during or after sex – do not take another dose; call 999 or go to A&E, especially if you feel breathless or unwell
- Severe allergic reaction (swelling of face, lips, tongue, or throat; difficulty breathing) – call 999 immediately
Call 999 or go to A&E in an emergency, or contact NHS 111 for urgent advice.
Scientific References
- NHS. (n.d.). Erectile dysfunction (impotence). NHS website. https://www.nhs.uk/conditions/erection-problems-erectile-dysfunction/ [accessed 21 October 2026]
- 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]
- Joint Formulary Committee. (n.d.). Sildenafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/sildenafil/ [accessed 21 October 2026]
- Joint Formulary Committee. (n.d.). Tadalafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/tadalafil/ [accessed 21 October 2026]
- Joint Formulary Committee. (n.d.). Vardenafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/vardenafil/ [accessed 21 October 2026]
- Joint Formulary Committee. (n.d.). Avanafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/avanafil/ [accessed 21 October 2026]
- Joint Formulary Committee. (n.d.). Alprostadil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/alprostadil/ [accessed 21 October 2026]
- Electronic Medicines Compendium. (n.d.). Summaries of Product Characteristics and Patient Information Leaflets. https://www.medicines.org.uk/emc/ [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.
Your Questions Answered
Can't find your answer? Our UK pharmacists review every consultation and can help.
Can I take tadalafil if I am on imatinib for leukaemia?
Yes, tadalafil and imatinib can be taken together, but your prescriber will usually start you on a lower dose of tadalafil because imatinib raises tadalafil levels in the blood. Declare all your medicines during your consultation so the prescriber can assess safety and adjust the dose appropriately.
Will imatinib make tadalafil less effective?
No, imatinib actually increases tadalafil levels, which can make the effects stronger and longer-lasting. This is why a lower starting dose is often recommended to reduce the risk of side effects such as headache or dizziness.
Do I need to tell my oncologist I am taking tadalafil?
Yes, it is good practice to inform your oncologist about all medicines you are taking, including tadalafil. This ensures coordinated care and allows your oncologist to advise on any additional considerations related to your cancer treatment.
What side effects should I watch for when taking tadalafil with imatinib?
Common side effects include headache, indigestion, back pain, flushing, and nasal congestion. Because imatinib raises tadalafil levels, these may be more noticeable. Contact your prescriber or GP if side effects are severe or persistent, or if you experience chest pain, prolonged erection, or sudden vision or hearing loss.
Can I take sildenafil (Viagra) instead of tadalafil if I am on imatinib?
Sildenafil is also metabolised by CYP3A4, so the same interaction applies: imatinib can raise sildenafil levels, and a lower starting dose may be needed. Your prescriber will choose the most suitable PDE5 inhibitor and dose based on your individual circumstances.
Is it safe to drink alcohol while taking tadalafil and imatinib?
Limit alcohol intake, as heavy drinking can worsen erectile dysfunction and add to the blood-pressure-lowering effect of tadalafil, increasing the risk of dizziness. Moderate alcohol (one or two units) is usually acceptable, but discuss your habits with your prescriber.
How long does tadalafil stay in my system if I am on imatinib?
Tadalafil normally has a half-life of about 17.5 hours, meaning effects can last up to 36 hours. Imatinib slows the breakdown of tadalafil, so it may stay in your system slightly longer. This is why your prescriber may recommend a lower dose and why you should not take tadalafil more than once in 24 hours.
Where can I get tadalafil if I am taking imatinib?
You can request tadalafil through Cured Pharmacy's online consultation service. A UK-registered prescriber will review your medical history and current medicines, including imatinib, to ensure tadalafil is safe and appropriate for you. If approved, your medicine will be dispensed by our GPhC-registered pharmacy and delivered discreetly to your door.
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Medically reviewed by
Tarun Kumar, Superintendent Pharmacist (GPhC 2233073)