Can You Take Tadalafil and Acrivastine Together?

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Tadalafil and Acrivastine: Understanding the Interaction

Published: 18 October 2026

Many men wonder whether tadalafil and acrivastine can be taken together safely. Tadalafil is a prescription medicine for erectile dysfunction (ED), while acrivastine is a non-drowsy antihistamine used for hay fever and allergies. The good news is that no major interaction between these two medicines is commonly reported, but there are still important considerations your prescriber will check before you start treatment.

What Is Tadalafil and How Does It Work?

Tadalafil is a phosphodiesterase type 5 (PDE5) inhibitor licensed in the UK to treat erectile dysfunction [4]. It works by relaxing blood vessels in the penis, allowing increased blood flow when you are sexually aroused. Unlike some other ED treatments, tadalafil has a long duration of action—its effects can last up to 36 hours, which is why it is sometimes called the 'weekend pill'.

Tadalafil is available in two forms: on-demand tablets (usually 10mg or 20mg taken at least 30 minutes before sexual activity) and daily low-dose tablets (2.5mg or 5mg taken once a day) [4]. Both require sexual stimulation to work. Tadalafil does not cure ED but can help you achieve and maintain an erection sufficient for sexual activity when you are aroused.

At Cured Pharmacy, tadalafil is available on prescription after an online consultation reviewed by a UK-registered prescriber. Generic tadalafil starts from £7.95, or £6.36 for your first order with code Ednew. Branded Cialis is also available at £12.00 (£9.60 with code Ednew).

What Is Acrivastine and When Is It Used?

Acrivastine is a second-generation antihistamine commonly sold under the brand name Benadryl Allergy Relief in the UK. It is used to relieve symptoms of hay fever (seasonal allergic rhinitis) and other allergies, such as sneezing, runny nose, itchy eyes, and skin rashes. Acrivastine is classified as a non-drowsy antihistamine, though a small number of people may still experience some drowsiness.

Unlike older antihistamines such as chlorphenamine, acrivastine is less likely to cross into the brain and cause sedation. It is usually taken as an 8mg capsule up to three times a day. Acrivastine is available to buy from pharmacies without a prescription for adults and children over 12 years old.

Because acrivastine is often taken during spring and summer months when pollen counts are high, many men using tadalafil for ED may need both medicines at the same time. Understanding how they interact is important for safe and effective treatment.

The Interaction Between Tadalafil and Acrivastine

No major interaction between tadalafil and acrivastine is commonly reported in the British National Formulary or clinical literature [4]. This means that, for most men, taking these two medicines together does not pose a significant safety risk. Acrivastine does not affect the way tadalafil is broken down in the body, and tadalafil does not interfere with acrivastine's antihistamine action.

However, both medicines can, in rare cases, cause dizziness or a drop in blood pressure. Tadalafil lowers blood pressure slightly as part of its mechanism of action, and some people may feel dizzy when standing up quickly, especially when first starting treatment [4]. Acrivastine can occasionally cause drowsiness or dizziness, although this is uncommon.

If you experience unusual dizziness, light-headedness, or fainting when taking tadalafil and acrivastine together, sit or lie down and contact your GP or pharmacist for advice. These symptoms are more likely if you are also taking other blood-pressure-lowering medicines, drink alcohol, or are dehydrated.

How the Interaction Works (Plain English)

Tadalafil relaxes blood vessels throughout the body, not just in the penis, which can cause a small drop in blood pressure. Acrivastine does not usually affect blood pressure, but it can occasionally cause dizziness through a different mechanism (mild sedation in sensitive individuals). When taken together, the risk of feeling dizzy is not significantly increased for most people, but it is something to be aware of, especially during the first few doses.

What Your Prescriber Checks Before Approving Tadalafil and Acrivastine

When you request tadalafil through Cured Pharmacy's online consultation, a UK-registered prescriber reviews your medical history and current medicines to ensure the treatment is safe for you. You will be asked to list all medicines you are taking, including over-the-counter products like acrivastine, herbal remedies, and supplements.

The prescriber will check for any contraindications—medicines that must never be taken with tadalafil. These include nitrates (such as GTN spray or isosorbide mononitrate), nicorandil, riociguat, and recreational drugs known as 'poppers' (amyl or alkyl nitrites). Taking tadalafil with any of these can cause a dangerous drop in blood pressure [4]. Do not take tadalafil with another PDE5 inhibitor (such as sildenafil or vardenafil) at the same time.

The prescriber will also review any medicines that may interact with tadalafil, such as alpha-blockers for prostate problems (e.g. tamsulosin, doxazosin), potent CYP3A4 inhibitors (e.g. ritonavir, ketoconazole, clarithromycin), and other blood-pressure medicines. If you are taking acrivastine, the prescriber will note this but it is unlikely to prevent you from being prescribed tadalafil, provided you have no other risk factors.

Declaring All Your Medicines

It is essential to declare every medicine you take, even if you bought it without a prescription. This includes antihistamines like acrivastine, painkillers, vitamins, and herbal products such as St John's wort. The prescriber uses this information to assess your individual risk and ensure tadalafil is the right choice for you.

Practical Advice for Taking Tadalafil and Acrivastine Safely

If your prescriber approves tadalafil and you are also taking acrivastine for allergies, follow these practical tips to minimise any risk. Take each medicine exactly as directed: tadalafil at least 30 minutes before sexual activity (or once daily if using the low-dose option), and acrivastine up to three times a day as needed for allergy symptoms.

Avoid drinking large amounts of alcohol when using tadalafil, as alcohol can worsen erectile dysfunction and increase the risk of dizziness and low blood pressure [4]. Stay well hydrated, especially during warm weather when you may be taking acrivastine for hay fever. If you feel dizzy or light-headed, sit or lie down until the feeling passes, and avoid driving or operating machinery.

Do not stop or change the dose of any prescribed medicine without consulting your GP or pharmacist. If you develop new symptoms, such as chest pain during sex, a prolonged erection lasting more than four hours, or sudden loss of vision or hearing, seek urgent medical help. These are rare but serious side effects of tadalafil that require immediate attention [4].

Other Medicines and Tadalafil: What Else to Watch For

While acrivastine does not pose a major interaction risk with tadalafil, other medicines do require careful management. Alpha-blockers (used for an enlarged prostate or high blood pressure) can cause a significant drop in blood pressure when combined with tadalafil [4]. If you take an alpha-blocker, you should be stable on that medicine before starting tadalafil, and your prescriber will usually recommend the lowest dose of tadalafil initially.

Potent CYP3A4 inhibitors—such as the HIV medicines ritonavir and cobicistat, the antifungals ketoconazole and itraconazole, and the antibiotic clarithromycin—can raise tadalafil levels in the blood, increasing the risk of side effects. Your prescriber may reduce the maximum dose of tadalafil or advise against using it altogether, depending on which medicine you are taking [4].

CYP3A4 inducers, such as rifampicin, carbamazepine, phenytoin, and St John's wort, can make tadalafil less effective by speeding up its breakdown in the body. Grapefruit juice can also raise tadalafil levels and should be avoided. Always tell your prescriber about every medicine and supplement you use, so they can give you the safest and most effective advice.

When to Seek Further Advice

If you start a new medicine while taking tadalafil, or if your GP changes the dose of an existing medicine, contact Cured Pharmacy or your GP to check whether your tadalafil treatment needs to be reviewed. Do not assume that a new medicine is safe to take with tadalafil without professional advice, even if it is available over the counter.

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. Joint Formulary Committee. (n.d.). Tadalafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/tadalafil/ [accessed 18 October 2026]
3. 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.