Tadalafil and Anastrozole: Can They Be Taken Together?

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Tadalafil and Anastrozole: Understanding the Interaction

Published: 18 October 2026

Many men wonder whether tadalafil and anastrozole can be taken together safely. Tadalafil is a PDE5 inhibitor used to treat erectile dysfunction, while anastrozole is an aromatase inhibitor prescribed mainly for hormone-receptor-positive breast cancer in postmenopausal women. No major direct interaction between these two medicines is commonly reported in clinical practice, but every person's situation is unique and your prescriber will check all your current medicines during consultation.

What is tadalafil and how does it work?

Tadalafil is the generic name for Cialis, 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. When you are sexually aroused, your body releases a chemical messenger called nitric oxide, which helps relax the smooth muscle in the blood vessels of the penis, allowing more blood to flow in and produce an erection.

Tadalafil works by blocking an enzyme (PDE5) that breaks down this messenger, helping the blood vessels stay relaxed for longer [4]. It 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 tablet (2.5 mg or 5 mg). Tadalafil does not cause an erection on its own—sexual stimulation is still needed [4].

At Cured Pharmacy, tadalafil is available from £7.95 after an online consultation reviewed by a UK prescriber. All current medicines and health conditions are checked before treatment is approved.

What is anastrozole and what is it used for?

Anastrozole is a medicine known as an aromatase inhibitor. It is most commonly prescribed to treat hormone-receptor-positive breast cancer in postmenopausal women [12]. Aromatase is an enzyme that converts androgens (male hormones) into oestrogen. By blocking this enzyme, anastrozole lowers the amount of oestrogen in the body, which can slow or stop the growth of certain types of breast cancer that need oestrogen to grow.

Anastrozole is usually taken as a 1 mg tablet once a day, often for several years as part of cancer treatment or to reduce the risk of cancer returning [12]. It does not directly affect the cardiovascular system in the same way that tadalafil does, and it is not metabolised by the same liver enzymes that interact with many ED medicines.

Some men may also encounter anastrozole in the context of testosterone replacement therapy or bodybuilding, where it is sometimes used off-licence to manage oestrogen levels. However, this use is not licensed in the UK and should only be undertaken under specialist medical supervision.

Do tadalafil and anastrozole interact with each other?

Based on current clinical evidence and prescribing guidance, there is no well-documented direct pharmacological interaction between tadalafil and anastrozole [4][12]. They work through different mechanisms and are metabolised by different pathways in the body. Tadalafil is primarily broken down by the liver enzyme CYP3A4, while anastrozole does not significantly inhibit or induce this enzyme.

This means that taking anastrozole is unlikely to raise or lower the levels of tadalafil in your blood, and tadalafil is not expected to interfere with how anastrozole works. However, every person's medical history is different, and the safety of combining any two medicines depends on your overall health, other medications you take, and any underlying conditions.

It is essential that you declare all your current medicines—including anastrozole—during your online consultation. The prescriber will review your full medication list, check for any potential issues, and ensure that tadalafil is safe and appropriate for you. Never start, stop, or change the dose of any prescribed medicine without speaking to your doctor or pharmacist first.

What your prescriber will check

During your consultation, the prescriber will ask about all medicines you are taking, including anastrozole, as well as any over-the-counter products, herbal remedies, and supplements. They will also review your cardiovascular health, blood pressure, and any history of heart disease, stroke, or other serious conditions that might make PDE5 inhibitors unsuitable [2][4]. Even when no direct interaction exists, your overall health picture matters. For example, if you are taking anastrozole as part of cancer treatment, your prescriber may want to ensure that your general fitness for sexual activity has been assessed by your oncologist or GP.

Medicines that do interact with tadalafil

While tadalafil and anastrozole do not have a known interaction, there are several other medicines that must never be taken with tadalafil because they can cause a dangerous drop in blood pressure [4]. Do not take tadalafil if you are using nitrates (such as GTN spray, isosorbide mononitrate, or isosorbide dinitrate), nicorandil, riociguat, or recreational drugs known as 'poppers' (amyl or alkyl nitrites). Never take tadalafil alongside another PDE5 inhibitor such as sildenafil, vardenafil, or avanafil.

Alpha-blockers (for example, doxazosin, tamsulosin, alfuzosin) used to treat high blood pressure or prostate symptoms can also interact with tadalafil, increasing the risk of dizziness or fainting [4]. If you take an alpha-blocker, you should be stable on that medicine and your prescriber will start you on the lowest dose of tadalafil.

Potent CYP3A4 inhibitors—including some HIV medicines (ritonavir, cobicistat), antifungals (ketoconazole, itraconazole), the antibiotic clarithromycin, and COVID-19 treatment Paxlovid—can raise tadalafil levels in your blood, requiring a lower maximum dose [4]. Conversely, CYP3A4 inducers such as rifampicin, carbamazepine, phenytoin, and St John's wort may reduce tadalafil's effectiveness. Always tell your prescriber about every medicine you take.

Practical advice when taking tadalafil and anastrozole together

If your prescriber confirms that tadalafil is safe for you while you are taking anastrozole, follow the dosing instructions carefully. On-demand tadalafil (10 mg or 20 mg) should be taken at least 30 minutes before sexual activity, and the effect can last up to 36 hours [4]. 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. Do not take more than one dose in 24 hours.

Store both medicines at room temperature, away from moisture and heat, and keep them out of reach of children. Avoid drinking large amounts of alcohol, as this can worsen erectile dysfunction and increase the risk of side effects such as dizziness or headache [4]. Grapefruit juice may also raise tadalafil levels and should be avoided.

If you experience any new or unusual symptoms after starting tadalafil—such as chest pain, severe dizziness, sudden vision or hearing loss, or an erection lasting more than four hours—seek urgent medical help. Continue taking anastrozole exactly as your oncologist or specialist has prescribed, and do not stop or change the dose without their advice. If you have any concerns about how your medicines work together, speak to your GP, specialist, or pharmacist.

When to see your GP

Erectile dysfunction can be an early warning sign of cardiovascular disease or diabetes, so it is important to see your GP if you are experiencing ED for the first time [1][2]. Your doctor can check for underlying health conditions, review all your medicines, and refer you to a specialist if needed. If you are already under the care of an oncologist or other specialist for the condition being treated with anastrozole, let them know if you are considering or have started treatment for ED, so they can ensure your overall care is coordinated.

How to get tadalafil safely online

Cured Pharmacy is a GPhC-registered online pharmacy (GPhC 9012511) offering convenient access to prescription ED treatments, including tadalafil. All orders require completion of an online consultation, which is reviewed by a UK-registered prescriber. You will be asked about your medical history, current medicines (including anastrozole), and any health conditions. The prescriber will check that tadalafil is safe and suitable for you before approving your order.

Tadalafil is available from £7.95 (or £6.36 for first orders with code Ednew). We also stock other PDE5 inhibitors such as sildenafil (from £0.45), vardenafil (£16.95), and Spedra (avanafil, £20.95), as well as branded Cialis (£12.00) and Viagra (£37.95). Your medicine is dispensed by our qualified pharmacists and delivered discreetly to your door.

Never buy prescription medicines from unregistered websites or without a proper consultation. Counterfeit or unlicensed products can be dangerous and may not contain the correct active ingredient. Always use a registered UK pharmacy and ensure a qualified prescriber has reviewed your health and medication history before treatment.

What happens during the consultation

The online consultation will ask about your general health, any heart or blood pressure problems, other medicines you take (including anastrozole), and whether you have had any previous reactions to ED treatments. The prescriber will check for contraindications and interactions, and may ask follow-up questions if needed. If tadalafil is not suitable, they may suggest an alternative treatment or advise you to see your GP. The consultation is confidential, and your information is handled in line with UK data protection laws.

Scientific References

1. NHS. (n.d.). Erectile dysfunction (impotence). NHS website. https://www.nhs.uk/conditions/erection-problems-erectile-dysfunction/ [accessed 18 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 18 October 2026]
3. Joint Formulary Committee. (n.d.). Tadalafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/tadalafil/ [accessed 18 October 2026]
4. Electronic Medicines Compendium. (n.d.). Summaries of Product Characteristics and Patient Information Leaflets. https://www.medicines.org.uk/emc/ [accessed 18 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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