Tadalafil and Silodosin: Can You Take Them Together?

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Key takeaways

• Tadalafil and silodosin can be used together, but only under medical supervision because both lower blood pressure.
• You must be stable on silodosin before starting tadalafil, and you will usually begin with the lowest dose.
• Stand up slowly to reduce the risk of dizziness or fainting, especially in the first few days.
• Never take tadalafil with nitrates, nicorandil, riociguat, or poppers—this combination is dangerous.
• Seek urgent help if you have an erection lasting over four hours, sudden vision or hearing loss, or chest pain.

What is tadalafil and silodosin, and why might you take both?

Tadalafil is a phosphodiesterase type 5 (PDE5) inhibitor used to treat erectile dysfunction (ED). It works by relaxing blood vessels in the penis, allowing more blood to flow in when you are sexually aroused, which helps you achieve and maintain an erection [3][4]. 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). It is the active ingredient in branded Cialis and is also available as a generic medicine.

Silodosin is an alpha-blocker (also called an alpha-1 adrenoceptor antagonist) prescribed to relieve urinary symptoms caused by benign prostatic hyperplasia (BPH), or an enlarged prostate. It works by relaxing the smooth muscle in the prostate and bladder neck, making it easier to pass urine. Because both ED and lower urinary tract symptoms are common in men over 50, it is not unusual for a man to be prescribed both tadalafil and silodosin at the same time [1][2].

However, both medicines can lower blood pressure—tadalafil by dilating blood vessels throughout the body, and silodosin by relaxing smooth muscle in blood vessels as well as the prostate. When taken together, this blood-pressure-lowering effect can add up, increasing the risk of dizziness, light-headedness, or fainting, especially when standing up quickly. This is why the combination requires careful prescriber assessment and a cautious approach to dosing.

How do tadalafil and silodosin interact in the body?

The interaction between tadalafil and silodosin is pharmacodynamic, meaning it relates to what the medicines do in your body rather than how they are broken down or absorbed. Both medicines cause vasodilation—widening of blood vessels—which lowers blood pressure. Tadalafil does this primarily in the blood vessels of the penis (and to a lesser extent elsewhere), while silodosin relaxes smooth muscle in the prostate and bladder neck but can also affect blood vessels, particularly when you stand up [3][4].

When you take both medicines together, their blood-pressure-lowering effects can combine, leading to a more pronounced drop in blood pressure than either medicine would cause alone. This is especially noticeable with postural hypotension (a sudden drop in blood pressure when you stand up), which can make you feel dizzy, light-headed, or even cause you to faint. The risk is highest when you first start taking the combination, when doses are increased, or if you are also taking other medicines that lower blood pressure.

It is important to understand that this interaction does not mean the combination is forbidden—many men use tadalafil and silodosin together successfully. However, it does mean that your prescriber must assess your overall health, check your current medicines, and usually start you on the lowest effective dose of tadalafil. You should also be stable on your alpha-blocker (meaning you have been taking it for a while without problems) before adding tadalafil [2][3][4].

Why alpha-blockers and PDE5 inhibitors require caution

Alpha-blockers like silodosin are known to interact with all PDE5 inhibitors (sildenafil, tadalafil, vardenafil, and avanafil), not just tadalafil. The British National Formulary and product information for these medicines all highlight the need for caution when combining them with alpha-blockers [3][4][5][6]. The key safety measure is to ensure you are already stable on your alpha-blocker before starting a PDE5 inhibitor, and to begin with the lowest dose of the ED medicine. Your prescriber will also check your blood pressure and ask about any symptoms of dizziness or fainting you may have experienced in the past.

At a glance

What will your prescriber check before approving tadalafil and silodosin together?

Before prescribing tadalafil to someone already taking silodosin (or any other alpha-blocker), a UK prescriber will carry out a thorough assessment to ensure the combination is safe for you. This assessment is a mandatory part of the online consultation at Cured Pharmacy and includes several important checks [2][3][4].

First, your prescriber will confirm that you are stable on silodosin—meaning you have been taking it for a reasonable period (usually at least a few weeks) without experiencing significant dizziness, fainting, or other side effects. They will ask about your blood pressure, any history of low blood pressure or postural hypotension, and whether you have ever fainted or felt dizzy when standing up. If you have a history of these symptoms, the prescriber may decide that adding tadalafil is not appropriate, or may recommend a very low starting dose and close monitoring.

Your prescriber will also review all your other medicines to check for additional interactions. For example, if you are taking other blood-pressure-lowering medicines (such as ACE inhibitors, calcium channel blockers, or diuretics), the combined effect on blood pressure will be considered. Importantly, the prescriber will confirm that you are not taking any medicines that are absolutely contraindicated with tadalafil, such as nitrates (GTN spray, isosorbide mononitrate), nicorandil, riociguat, or recreational drugs known as poppers (amyl or alkyl nitrites). These combinations can cause a dangerous, life-threatening drop in blood pressure and must never be used together [3][4].

Finally, your prescriber will check that tadalafil is suitable for your overall cardiovascular health. ED medicines are not recommended if sexual activity itself is inadvisable—for example, if you have had a recent heart attack or stroke, have unstable angina, or have severe heart failure. Your prescriber will also ask about any history of sudden vision or hearing loss, as these are rare but serious side effects that require caution [1][2][3][4].

Practical advice for taking tadalafil with silodosin safely

If your prescriber approves the combination of tadalafil and silodosin, there are several practical steps you can take to minimise the risk of side effects and use both medicines safely. The most important is to start with the lowest effective dose of tadalafil. For on-demand use, this is usually 10 mg, and your prescriber may recommend staying on this dose rather than increasing to 20 mg unless it is clearly necessary. If you are considering daily tadalafil, the starting dose is typically 2.5 mg, which can be increased to 5 mg if needed and tolerated [3][4].

Take your time when standing up, especially in the first few days after starting tadalafil or after any dose increase. Sit on the edge of the bed or chair for a moment before standing, and rise slowly to give your body time to adjust. This simple measure can significantly reduce the risk of dizziness or fainting caused by postural hypotension. Avoid situations where a sudden drop in blood pressure could be dangerous, such as climbing ladders or operating heavy machinery, until you know how the combination affects you.

Be mindful of alcohol intake. Drinking heavily can worsen erectile dysfunction and also adds to the blood-pressure-lowering effect of both tadalafil and silodosin, increasing the risk of dizziness. It is best to limit alcohol to moderate amounts (no more than two units) when using these medicines together [1][3][4]. Similarly, avoid grapefruit juice, as it can raise the level of tadalafil in your blood and increase the risk of side effects.

If you experience persistent dizziness, light-headedness, fainting, or any chest pain (especially during sexual activity), stop taking tadalafil and contact your GP or prescriber immediately. These symptoms may indicate that your blood pressure is dropping too low, or that there is another problem that needs urgent assessment. Never adjust the dose of either medicine on your own—always discuss any concerns with your prescriber first [2][3][4].

What if you are taking other alpha-blockers?

Silodosin is one of several alpha-blockers used for prostate symptoms. Others include tamsulosin, alfuzosin, doxazosin, terazosin, prazosin, and indoramin. The advice about combining tadalafil (or any PDE5 inhibitor) with an alpha-blocker applies to all of these medicines, not just silodosin. If you are taking a different alpha-blocker, the same precautions—being stable on the alpha-blocker, starting with a low dose of tadalafil, and monitoring for dizziness—are essential. Your prescriber will assess the specific alpha-blocker you are taking and tailor the advice accordingly [3][4][5][6].

Warning signs: when to seek urgent help with tadalafil and silodosin

While most men tolerate the combination of tadalafil and silodosin well, it is important to be aware of warning signs that require urgent medical attention. These are rare but can be serious, and knowing what to look out for can help you act quickly if needed [1][3][4].

The most important warning sign is an erection that lasts longer than four hours (priapism). This is a medical emergency because prolonged erection can damage the tissues of the penis and lead to permanent erectile dysfunction if not treated promptly. If you have an erection lasting more than four hours, go to your nearest accident and emergency (A&E) department immediately, even if it is not painful.

Sudden loss of vision in one or both eyes, or sudden decrease or loss of hearing (which may be accompanied by ringing in the ears or dizziness), are also medical emergencies. These are very rare side effects of PDE5 inhibitors, but if they occur, stop taking tadalafil and seek urgent medical help. Similarly, if you experience chest pain during or after sexual activity, stop what you are doing and seek immediate medical advice. Chest pain could indicate a heart problem, and you should not take another dose of tadalafil until you have been assessed by a doctor [1][3][4].

Severe dizziness, fainting, or a feeling that you are about to pass out—especially when standing up—may indicate that your blood pressure has dropped too low. If this happens, sit or lie down immediately, and contact your GP or NHS 111 for advice. Do not drive or operate machinery if you feel dizzy or faint. Your prescriber may need to adjust your dose or review whether the combination is suitable for you.

How Cured Pharmacy can help with tadalafil and silodosin

Cured Pharmacy is a GPhC-registered online pharmacy (GPhC 9012511) offering a convenient, confidential service for men who need treatment for erectile dysfunction. If you are taking silodosin (or another alpha-blocker) and would like to try tadalafil, you can complete a short online consultation that will be reviewed by a UK-registered prescriber. The prescriber will assess your medical history, current medicines, and overall health to ensure that tadalafil is safe and appropriate for you [2][3][4].

We stock a range of tadalafil options to suit different needs and budgets. Generic tadalafil is available from £7.95 for on-demand tablets, or £6.36 for first orders using code Ednew. We also offer branded Cialis at £12.00 (£9.60 with code Ednew), Tadalafil 20 mg (Teva) at £9.99 (£7.99 with code Ednew), and Avarante (tadalafil) 10 mg at £11.49 (£9.19 with code Ednew). All tadalafil products require a prescription, which is issued after your consultation is approved.

If tadalafil is not suitable for you—for example, because of the interaction with silodosin or another medicine—our prescribers can discuss alternative ED treatments. These include other PDE5 inhibitors such as sildenafil (from £0.45, or £0.36 with code Ednew), vardenafil (£16.95, or £13.56 with code Ednew), or avanafil (Spedra, £20.95, or £16.76 with code Ednew). Each of these medicines has a slightly different profile, and your prescriber will help you find the option that is safest and most effective for your situation.

Our service is designed to be discreet, straightforward, and supportive. Medicines are delivered in plain, unmarked packaging, and our pharmacist-led team is available to answer any questions you may have about your treatment. If you have any concerns about taking tadalafil with silodosin, or if you experience any side effects, you can contact us for advice at any time.

Why see a GP for new erectile dysfunction

If you are experiencing erectile dysfunction for the first time, it is important to see your GP for a full assessment before starting treatment. ED can be an early warning sign of underlying health conditions such as heart disease, high blood pressure, or diabetes, and addressing these conditions can improve both your overall health and your erectile function [1][2][10]. Your GP can carry out tests, review your medicines, and discuss lifestyle changes that may help. Once any underlying causes have been addressed, an online consultation for ED treatment can be a convenient and effective way to access ongoing care.

When to get urgent help

• Erection lasting longer than four hours (priapism)—go to A&E immediately
• Sudden loss of vision in one or both eyes—stop tadalafil and seek urgent medical help
• Sudden decrease or loss of hearing, possibly with ringing in the ears—stop tadalafil and get urgent advice
• Chest pain during or after sexual activity—stop and seek immediate medical assessment
• Severe dizziness or fainting, especially when standing—sit or lie down and contact your GP or NHS 111

Call 999 or go to A&E in an emergency, or contact NHS 111 for urgent advice.