Tadalafil and Dutasteride: Can You Take Them Together?

Tadalafil and Dutasteride: Understanding the Interaction

Published: 20 October 2026

Many men wonder whether tadalafil and dutasteride can be taken together safely. The good news is that no major interaction is commonly reported between these two medicines, and they are often prescribed alongside one another. Tadalafil is used to treat erectile dysfunction (ED), while dutasteride is prescribed for benign prostatic hyperplasia (BPH, an enlarged prostate) and sometimes for male pattern hair loss. This page explains what each medicine does, how they may affect each other, what your prescriber will check, and practical advice for taking them together.

What is tadalafil and dutasteride used for?

Tadalafil is a phosphodiesterase type 5 (PDE5) inhibitor licensed in the UK for erectile dysfunction and the urinary symptoms of benign prostatic hyperplasia [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 (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) for continuous treatment [4]. Sexual stimulation is still required for the medicine to work.

Dutasteride is a 5-alpha reductase inhibitor used to treat benign prostatic hyperplasia (BPH) in men with an enlarged prostate [12]. It works by blocking the conversion of testosterone to dihydrotestosterone (DHT), a hormone that contributes to prostate growth. By lowering DHT levels, dutasteride can shrink the prostate over time and improve urinary symptoms such as difficulty starting urination, weak stream, and frequent nighttime trips to the toilet. Dutasteride is also sometimes prescribed off-label for male pattern hair loss, though finasteride (a related medicine) is more commonly used for this purpose.

Both medicines are prescription-only in the UK and require a clinical assessment by a registered prescriber. At Cured Pharmacy, an online consultation is reviewed by a UK prescriber before any prescription treatment is supplied.

Is there an interaction between tadalafil and dutasteride?

No major interaction is commonly reported between tadalafil and dutasteride, and they are often prescribed together, particularly in men who have both erectile dysfunction and urinary symptoms from an enlarged prostate [2][4]. Dutasteride does not significantly affect the way tadalafil is broken down in the body, and tadalafil does not interfere with the mechanism of dutasteride.

However, both medicines can individually lower blood pressure slightly. Tadalafil relaxes blood vessels throughout the body (not just in the penis), which can cause a small drop in blood pressure. Dutasteride does not typically cause low blood pressure on its own, but when taken with tadalafil, the combined effect on blood pressure is usually mild and well tolerated. Your prescriber will check your current blood pressure and any other medicines you take to ensure the combination is safe for you.

It is important to declare all your current medicines during your consultation, including over-the-counter products and supplements. Your prescriber will review your full medication list and medical history to identify any potential issues. If you experience dizziness, lightheadedness, or fainting after starting tadalafil, contact your GP or pharmacist for advice.

What does your prescriber check before approving tadalafil and dutasteride together?

During your online consultation, the prescriber will review your medical history, current medicines, and overall health to ensure tadalafil is safe and appropriate for you. They will check whether you have any conditions that make PDE5 inhibitors unsuitable, such as recent heart attack or stroke, unstable angina, severe heart failure, very low blood pressure, or a history of sudden vision loss (non-arteritic anterior ischaemic optic neuropathy, or NAION) [4].

The prescriber will also confirm that you are not taking any medicines that must never be combined with tadalafil. These include nitrates (such as GTN spray, isosorbide mononitrate, or isosorbide dinitrate), nicorandil, riociguat, and amyl or alkyl nitrites (poppers). Taking tadalafil with any of these can cause a dangerous fall in blood pressure [4]. You must also not take another PDE5 inhibitor (such as sildenafil, vardenafil, or avanafil) at the same time as tadalafil.

If you are taking an alpha-blocker (such as doxazosin, tamsulosin, alfuzosin, or terazosin) for urinary symptoms or high blood pressure, your prescriber will ensure you are stable on that medicine and may start you on the lowest dose of tadalafil to reduce the risk of dizziness or low blood pressure [4]. Dutasteride itself does not raise significant concerns when combined with tadalafil, but the prescriber will still review the full picture to ensure the combination is right for you.

Medicines that affect tadalafil levels

Certain medicines can raise or lower the levels of tadalafil in your blood. Potent CYP3A4 inhibitors (such as ritonavir, cobicistat, ketoconazole, itraconazole, and clarithromycin) can increase tadalafil levels, which may increase the risk of side effects. If you are taking one of these medicines, your prescriber may reduce the maximum dose of tadalafil [4]. CYP3A4 inducers (such as rifampicin, carbamazepine, phenytoin, and St John's wort) can lower tadalafil levels and make it less effective. Your prescriber will check for these interactions during your consultation.

Practical advice for taking tadalafil and dutasteride together

If you have been prescribed both tadalafil and dutasteride, you can take them at the same time or at different times of day—there is no need to separate the doses. Dutasteride is usually taken once daily, at the same time each day, with or without food. Tadalafil can be taken as needed (on-demand) or once daily, depending on the dose and your prescriber's advice. If you are using on-demand tadalafil, take it at least 30 minutes before sexual activity; the effect can last up to 36 hours, so you do not need to time it precisely [4].

Avoid drinking large amounts of alcohol while taking tadalafil, as heavy drinking can worsen erectile dysfunction and add to the blood-pressure-lowering effect, increasing the risk of dizziness or fainting. Grapefruit juice can raise tadalafil levels in the blood, so it is best to avoid it or limit your intake. If you experience dizziness when standing up, get up slowly from sitting or lying down, especially when you first start treatment.

Dutasteride can take several months to show its full effect on prostate size and urinary symptoms, so continue taking it as prescribed even if you do not notice immediate improvement. Tadalafil, on the other hand, works within 30 minutes to a few hours for erectile dysfunction. Remember that sexual stimulation is needed for tadalafil to work—it will not cause an erection on its own. If you have any concerns or side effects, contact your GP or pharmacist for advice.

Tadalafil and dutasteride: what about other medicines for BPH or hair loss?

Dutasteride belongs to a class of medicines called 5-alpha reductase inhibitors. Finasteride is another medicine in this class, used for BPH and male pattern hair loss. The advice for taking tadalafil with finasteride is the same as for dutasteride: no major interaction is commonly reported, and they are often prescribed together [2][4]. If you are taking finasteride instead of dutasteride, the same precautions apply.

Alpha-blockers (such as tamsulosin, doxazosin, alfuzosin, and terazosin) are also used to treat urinary symptoms of BPH. These medicines can interact with tadalafil, causing a greater drop in blood pressure and an increased risk of dizziness or fainting. If you are taking an alpha-blocker, your prescriber will ensure you are stable on that medicine before starting tadalafil, and they may recommend starting with the lowest dose of tadalafil [4]. Do not stop or change your alpha-blocker without your doctor's advice.

For male pattern hair loss, some men use topical treatments such as minoxidil (Regaine) alongside dutasteride or finasteride. Topical minoxidil does not interact with tadalafil. If you are considering any new treatment for hair loss or BPH, discuss it with your GP or pharmacist to ensure it is safe to take with your current medicines.

Can I take tadalafil with other blood pressure medicines?

Tadalafil can add to the blood-pressure-lowering effect of other medicines used to treat high blood pressure, such as ACE inhibitors, angiotensin receptor blockers (ARBs), calcium channel blockers, and beta-blockers. This is usually manageable, but you must declare all your current medicines during your consultation so the prescriber can assess the risk. If you are taking multiple blood pressure medicines, your prescriber may start you on a lower dose of tadalafil and monitor you closely. Never stop or change a prescribed blood pressure medicine without your doctor's advice.

Warning signs and when to seek help with tadalafil and dutasteride

Most men tolerate tadalafil and dutasteride well, but it is important to know the warning signs that need urgent medical attention. If you develop an erection that lasts longer than 4 hours (priapism), go to A&E immediately or call 999. Priapism is a medical emergency that can cause permanent damage to the penis if not treated promptly [4]. Do not wait to see if it goes away on its own.

Sudden loss of vision in one or both eyes, or sudden decrease or loss of hearing (sometimes with ringing in the ears or dizziness), are rare but serious side effects of PDE5 inhibitors. Stop taking tadalafil and seek urgent medical help if this happens [4]. If you experience chest pain during or after sex, do not use nitrate medicines (such as GTN spray) to relieve it—tell the paramedics or doctor that you have taken tadalafil, as nitrates can cause a dangerous drop in blood pressure when combined with PDE5 inhibitors.

Common side effects of tadalafil include headache, indigestion, back pain, muscle aches, flushing, and a stuffy or runny nose [4]. These are usually mild and go away on their own. Dutasteride can cause decreased libido, erectile dysfunction (in some men), breast tenderness or enlargement, and mood changes in a small number of users [12]. If you experience severe or persistent side effects from either medicine, contact your GP or pharmacist for advice. Do not stop taking a prescribed medicine without professional guidance.

What if tadalafil does not work for me?

If tadalafil does not improve your erections, speak to your prescriber. They may adjust your dose, suggest trying a different PDE5 inhibitor (such as sildenafil, vardenafil, or avanafil), or refer you to a specialist for further assessment [2]. Erectile dysfunction can be an early warning sign of heart disease or diabetes, so it is important to see your GP if you develop new or worsening ED [1]. Your GP can check for underlying health conditions and discuss other treatment options, including vacuum devices, alprostadil (Vitaros cream or Caverject injection), or referral to a specialist clinic.

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.). Tadalafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/tadalafil/ [accessed 20 October 2026]
4. 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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