Tadalafil and Olmesartan: Can You Take Them Together?

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What Is Tadalafil and How Does It Work?

Tadalafil is a prescription medicine licensed in the UK to treat erectile dysfunction (ED). It belongs to a group of medicines called PDE5 inhibitors, which work by relaxing blood vessels in the penis, allowing increased blood flow when you are sexually aroused [3][4]. Tadalafil is the active ingredient in branded Cialis and is also available as a lower-cost generic.

Tadalafil is available in two forms: on-demand tablets (10 mg or 20 mg) taken at least 30 minutes before sexual activity, with effects lasting up to 36 hours, and daily low-dose tablets (2.5 mg or 5 mg) taken once a day [4]. All forms require sexual stimulation to work—they do not cause an automatic erection.

Because tadalafil widens blood vessels, it can also cause a small drop in blood pressure. This effect is usually mild and well-tolerated, but it becomes important when tadalafil is combined with other medicines that also lower blood pressure, such as olmesartan [4].

What Is Olmesartan and Why Is It Prescribed?

Olmesartan is an angiotensin II receptor blocker (ARB), a type of medicine used to treat high blood pressure (hypertension). It works by blocking the action of a hormone called angiotensin II, which normally causes blood vessels to narrow. By blocking this hormone, olmesartan helps blood vessels relax and widen, which lowers blood pressure and reduces the strain on your heart.

Olmesartan is usually taken once daily and is often prescribed when other blood pressure medicines, such as ACE inhibitors, cause troublesome side effects like a persistent dry cough. It may also be used in combination with other antihypertensive medicines to achieve better blood pressure control.

Like all blood pressure medicines, olmesartan can occasionally cause dizziness or light-headedness, especially when you first start taking it or if the dose is increased. This is because your body is adjusting to the lower blood pressure. These effects are relevant when considering the use of tadalafil alongside olmesartan.

Other Angiotensin II Receptor Blockers (ARBs)

Olmesartan belongs to a class of medicines that includes losartan, valsartan, candesartan, irbesartan, and telmisartan. All ARBs work in a similar way and have similar interactions with tadalafil. If you take any ARB, the same precautions and monitoring apply when considering ED treatment.

How Do Tadalafil and Olmesartan Interact?

Tadalafil and olmesartan can be taken together, but there is an additive effect on blood pressure. Both medicines work to lower blood pressure—olmesartan by blocking angiotensin II receptors and tadalafil by relaxing blood vessels. When taken together, the combined blood-pressure-lowering effect can be greater than either medicine alone [4].

In most men whose blood pressure is well controlled on olmesartan, this interaction is manageable and does not cause problems. However, some men may experience symptoms of low blood pressure, such as dizziness, light-headedness, or fainting, particularly when standing up quickly. This risk is higher if your blood pressure is not well controlled, if you are dehydrated, or if you take other medicines that also lower blood pressure.

There is no absolute contraindication to using tadalafil with olmesartan—unlike the dangerous interaction between tadalafil and nitrates (such as GTN spray), which must never be combined. Instead, the interaction with olmesartan requires careful prescriber assessment and, if appropriate, starting on a lower dose of tadalafil to minimise the risk of symptomatic low blood pressure [4].

What you need to know

• Tadalafil and olmesartan can usually be taken together if your blood pressure is stable and well controlled.
• Both medicines lower blood pressure, so your prescriber may start you on a lower dose of tadalafil.
• Watch for dizziness or light-headedness, especially when standing up quickly, and avoid heavy alcohol.
• Always declare all your medicines during your consultation, including olmesartan and any other blood pressure treatments.
• Never take tadalafil with nitrates, nicorandil, or riociguat—this combination is dangerous.

What Your Prescriber Will Check Before Prescribing Tadalafil and Olmesartan

Before prescribing tadalafil to someone taking olmesartan, a UK prescriber will review your full medical history and current medicines. They will check that your blood pressure is stable and well controlled on olmesartan, as uncontrolled high blood pressure or very low blood pressure can make tadalafil unsuitable [2][4].

Your prescriber will also ask about your cardiovascular health, including any history of heart attack, stroke, angina, or heart failure. Sexual activity places extra demand on the heart, so it is important to ensure that your heart is healthy enough for sex. If you have unstable angina, severe heart failure, or have had a recent heart attack or stroke, tadalafil may not be safe [4].

The prescriber will review all your other medicines to check for interactions. They will look for nitrates (such as GTN spray or isosorbide mononitrate), nicorandil, riociguat, or another PDE5 inhibitor, all of which must never be taken with tadalafil. They will also check for alpha-blockers (such as doxazosin or tamsulosin), which can add to the blood-pressure-lowering effect, and medicines that affect how tadalafil is broken down in the body [3][4].

If tadalafil is appropriate, your prescriber may recommend starting with a lower dose (such as 10 mg on-demand or 2.5 mg daily) to see how you tolerate the combination. They may also advise monitoring your blood pressure at home or at your GP surgery after starting treatment.

Declaring All Your Medicines

It is essential to declare every medicine you take during your consultation, including over-the-counter medicines, herbal remedies, and supplements. Even medicines you take occasionally, such as GTN spray for angina, must be disclosed. Your prescriber cannot assess safety without a complete picture of your treatment.

Practical Advice for Taking Tadalafil and Olmesartan Together

If your prescriber approves the combination of tadalafil and olmesartan, there are several practical steps you can take to use both medicines safely. First, take both medicines exactly as prescribed. Do not take more tadalafil than recommended, and do not skip doses of olmesartan without consulting your GP, as this could cause your blood pressure to rise [4].

Be aware of the signs of low blood pressure, which include dizziness, light-headedness, feeling faint, or blurred vision. These symptoms are most likely when you stand up quickly (a phenomenon called postural hypotension). To reduce this risk, stand up slowly from sitting or lying down, especially in the first few hours after taking tadalafil. If you feel dizzy, sit or lie down until the feeling passes.

Avoid heavy alcohol when taking tadalafil, as alcohol can lower blood pressure further and make side effects more likely. Alcohol can also make it harder to get an erection, reducing the effectiveness of tadalafil. Staying well hydrated is important, as dehydration can worsen low blood pressure. Grapefruit juice can increase tadalafil levels in your blood and should be avoided [4].

If you experience chest pain during or after sexual activity, stop and seek urgent medical help. Do not take GTN or any nitrate medicine if you have used tadalafil in the past 48 hours, as this combination can cause a dangerous drop in blood pressure. Tell the paramedics or A&E staff that you have taken tadalafil [4].

When to get urgent help

• Erection lasting more than 4 hours (priapism)—go to A&E immediately
• Sudden loss of vision or hearing—seek urgent medical help
• Chest pain during or after sex—call 999; do not take GTN if you have used tadalafil in the past 48 hours
• Severe dizziness, fainting, or collapse—call 999 or go to A&E
• Allergic reaction (swelling of face, lips, tongue, or throat; difficulty breathing)—call 999

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

When to Seek Medical Advice About Tadalafil and Olmesartan

You should contact your GP or prescriber if you experience persistent dizziness, fainting, or any new symptoms after starting tadalafil while taking olmesartan. These could be signs that your blood pressure is too low and your treatment may need adjusting. Do not stop taking olmesartan without medical advice, as this could cause your blood pressure to rise suddenly.

Seek urgent medical help (call 999 or go to A&E) if you have an erection lasting more than four hours (priapism), sudden loss of vision or hearing, or chest pain during sex. Priapism is a medical emergency that requires immediate treatment to prevent permanent damage. Sudden vision or hearing loss is rare but requires urgent assessment [4].

If you develop new symptoms or are prescribed a new medicine by your GP or another doctor, check with your prescriber or pharmacist whether it is safe to continue taking tadalafil. Some medicines, such as nitrates for angina, are absolutely contraindicated with tadalafil and must never be combined [3][4].

Remember that erectile dysfunction can be an early warning sign of cardiovascular disease or diabetes. If you have not seen your GP about your ED, it is worth making an appointment for a general health check, even if you are using an online service for ED treatment [1][2].

Online Consultations at Cured Pharmacy

At Cured Pharmacy, every prescription for tadalafil or another ED medicine is issued only after an online consultation reviewed by a UK-registered prescriber. The consultation asks about your medical history, current medicines, and cardiovascular health to ensure treatment is safe and appropriate for you. If you have any questions or concerns about taking tadalafil with olmesartan, you can discuss them during your consultation.