Can You Take Tadalafil and Losartan Together?

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What is tadalafil and how does it work?

Tadalafil is a prescription medicine used to treat erectile dysfunction (ED) in men [4]. It belongs to a group of medicines called PDE5 inhibitors, which work by relaxing blood vessels in the penis, allowing more blood to flow in when you are sexually aroused. Tadalafil does not cause an erection on its own—sexual stimulation is still needed for it to work.

Tadalafil is available in two ways: on-demand tablets (usually 10mg or 20mg) taken at least 30 minutes before sexual activity, with effects lasting up to 36 hours, or daily low-dose tablets (2.5mg or 5mg) taken once a day [4]. The longer duration of action is why tadalafil is sometimes called 'the weekend pill'. Common brand names include Cialis, but generic tadalafil works in exactly the same way and is more affordable.

Like all medicines, tadalafil can cause side effects in some people, including headache, indigestion, back pain, muscle aches, flushing, and nasal congestion [4]. Most side effects are mild and short-lived. Tadalafil is only available on prescription after a consultation with a UK prescriber, who will check it is safe and suitable for you.

What is losartan and why is it prescribed?

Losartan is a prescription medicine used to treat high blood pressure (hypertension) and to protect the kidneys in people with type 2 diabetes. It belongs to a class of medicines called angiotensin II receptor blockers (ARBs), which work by blocking the action of a hormone that narrows blood vessels, allowing blood vessels to relax and widen so blood pressure falls.

High blood pressure is very common in the UK and often has no symptoms, but over time it increases the risk of heart attacks, strokes, and kidney problems. Losartan is usually taken once a day, and it may take several weeks to see the full benefit on your blood pressure. Common side effects include dizziness (especially when standing up), tiredness, and headache.

Interestingly, high blood pressure itself is a risk factor for erectile dysfunction, because it can damage blood vessels throughout the body, including those supplying the penis [1]. Treating high blood pressure with medicines like losartan can improve overall cardiovascular health, which may in turn help with erectile function over time. However, some men still experience ED and may benefit from additional treatment with a medicine like tadalafil.

Does losartan cause erectile dysfunction?

Losartan and other ARBs are generally considered less likely to cause erectile dysfunction compared to some older blood-pressure medicines, such as certain beta-blockers or thiazide diuretics. In fact, some studies suggest ARBs may even have a neutral or slightly beneficial effect on sexual function. If you have noticed changes in your erections since starting losartan, it is important to discuss this with your GP, as the underlying high blood pressure—not the medicine—may be the main cause.

Can you take tadalafil and losartan together?

Yes, tadalafil and losartan can usually be taken together, but your prescriber must assess your individual situation first. Both medicines can lower blood pressure: losartan does so as its main action, while tadalafil has a mild blood-pressure-lowering effect as a side effect [4]. When taken together, there is a risk that your blood pressure could drop too much, leading to dizziness, light-headedness, or fainting, especially when you stand up quickly.

This interaction is not a reason to avoid tadalafil altogether—it simply means your prescriber will check that your blood pressure is well controlled on losartan, that you are not experiencing symptoms of low blood pressure, and that you start on an appropriate dose of tadalafil. For most men on stable losartan therapy, tadalafil is safe and effective when prescribed carefully.

It is important to be honest during your consultation about all the medicines you take, including over-the-counter products and supplements. Your prescriber will review your full medication list, your blood pressure readings, and any symptoms you have experienced. Never take tadalafil without a prescription, and never stop or change your losartan dose without speaking to your GP or pharmacist first.

What you need to know

• Tadalafil and losartan can usually be taken together if your blood pressure is stable.
• Both medicines can lower blood pressure, so your prescriber will adjust your dose carefully.
• Never take tadalafil with nitrate medicines—this combination is dangerous.
• Report any dizziness or light-headedness to your prescriber or pharmacist.
• All tadalafil prescriptions at Cured Pharmacy are reviewed by UK-registered prescribers.

How does the interaction between tadalafil and losartan work?

To understand the interaction, it helps to know how each medicine affects your blood vessels. Losartan relaxes and widens blood vessels throughout your body by blocking a hormone that causes them to narrow, which lowers your blood pressure. Tadalafil also relaxes blood vessels, but it does so by increasing levels of a natural chemical called cyclic GMP, which has a similar widening effect—primarily in the penis, but to a smaller extent elsewhere in the body [4].

When you take both medicines together, their blood-vessel-relaxing effects can add up, leading to a greater drop in blood pressure than either medicine alone. For most men, this additive effect is small and causes no problems, especially if the blood pressure was well controlled to begin with. However, in some cases it can cause symptoms such as dizziness, feeling faint, or a rapid heartbeat, particularly when moving from sitting to standing.

This is why your prescriber will often recommend starting tadalafil at a lower dose if you are taking losartan or any other blood-pressure medicine. The usual starting dose for on-demand tadalafil is 10mg, but your prescriber may suggest starting at 5mg or adjusting the timing of your doses to minimise the risk of low blood pressure. If you experience any dizziness or light-headedness after taking tadalafil, sit or lie down until you feel better, and let your prescriber know at your next review.

What your prescriber will check

During your consultation, your prescriber will ask about your current blood pressure readings, whether you have ever felt dizzy or faint on losartan, and whether you have any other heart or circulation problems. They will also check for any other medicines or health conditions that might make tadalafil unsuitable, such as recent heart attack or stroke, severe heart failure, or use of nitrate medicines (which must never be taken with tadalafil). This careful assessment ensures tadalafil is prescribed safely and at the right dose for you.

Practical advice for taking tadalafil with losartan

If your prescriber decides tadalafil is suitable for you, there are some practical steps you can take to use it safely alongside losartan. First, take tadalafil exactly as prescribed—do not take more than one dose in 24 hours, and do not exceed the maximum dose your prescriber has recommended. If you are using on-demand tadalafil, take it at least 30 minutes before sexual activity; if you are on daily tadalafil, take it at the same time each day.

Be mindful of situations that can make low blood pressure worse. Avoid drinking large amounts of alcohol, as this can add to the blood-pressure-lowering effect and may also make it harder to get an erection [1]. Stay well hydrated, especially in hot weather or after exercise. When you get up from sitting or lying down, do so slowly to give your body time to adjust and reduce the risk of dizziness.

Monitor how you feel after taking tadalafil, especially the first few times. If you notice dizziness, light-headedness, or any other unusual symptoms, make a note and discuss them with your prescriber or pharmacist. Do not stop taking losartan or adjust your dose without medical advice, as this could cause your blood pressure to rise. If you have any concerns or questions, Cured Pharmacy's team is available to help, and all prescriptions are reviewed by UK-registered prescribers to ensure your safety.

When to get urgent help

• Chest pain during or after sexual activity—call 999 immediately
• Erection lasting longer than 4 hours—seek emergency medical help
• Sudden loss of vision or hearing—go to A&E or call 999
• Severe dizziness, fainting, or very fast heartbeat—call 999 or 111 for advice
• Do not take nitrate medicines (GTN spray) within 48 hours of using tadalafil

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

When to seek urgent medical help

While serious side effects from taking tadalafil and losartan together are uncommon, it is important to know the warning signs that need urgent attention. If you experience chest pain or discomfort during or after sexual activity, stop what you are doing and seek immediate medical help—call 999 or go to A&E. Do not take any nitrate medicine (such as GTN spray) if you have used tadalafil in the past 48 hours, as this combination can cause a dangerous drop in blood pressure.

If you develop an erection that lasts longer than four hours (known as priapism), seek emergency medical help straight away, as this can cause permanent damage to the penis if not treated promptly [4]. 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 that require immediate medical attention.

Severe dizziness, fainting, or a very fast or irregular heartbeat after taking tadalafil may indicate that your blood pressure has dropped too low. If this happens, lie down with your legs raised, and call 111 or your GP for advice. If symptoms are severe or you feel very unwell, call 999. Always keep your prescriber informed of any side effects, even if they seem minor, so your treatment can be adjusted if needed.

Other medicines to mention

In addition to losartan, make sure your prescriber knows about any other medicines you take. Alpha-blockers (such as tamsulosin or doxazosin, used for prostate problems or blood pressure) can also interact with tadalafil and require careful dose adjustment. Never take tadalafil with nitrates, nicorandil, riociguat, or recreational drugs called 'poppers', as these combinations are dangerous [4]. Some antibiotics and antifungal medicines can increase tadalafil levels in your body, so always declare everything you are taking during your consultation.