Tadalafil and Mefenamic Acid: Can You Take Them Together?

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Tadalafil and Mefenamic Acid: Understanding the Interaction

Published: 23 October 2026

Many men wonder whether tadalafil and mefenamic acid can be taken together safely. The good news is that no major direct interaction is commonly reported between tadalafil (Cialis) and mefenamic acid (Ponstan), a non-steroidal anti-inflammatory drug (NSAID) used for period pain and other types of pain. However, both medicines can affect your cardiovascular system in different ways, so it's important to understand what your prescriber checks and when to seek advice.

What is tadalafil and mefenamic acid used for?

Tadalafil is a phosphodiesterase type 5 (PDE5) inhibitor licensed in the UK to treat erectile dysfunction (ED) and, at lower doses, benign prostatic hyperplasia (enlarged prostate). 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 (10mg or 20mg taken at least 30 minutes before sex, with effects lasting up to 36 hours) or as a daily low-dose option (2.5mg or 5mg). Sexual stimulation is always needed for tadalafil to work [4].

Mefenamic acid belongs to a group of medicines called non-steroidal anti-inflammatory drugs (NSAIDs). It is commonly prescribed for period pain (dysmenorrhoea), heavy periods (menorrhagia), and other types of short-term pain such as headaches, dental pain, or muscle aches. Mefenamic acid works by blocking enzymes (cyclooxygenase) that produce prostaglandins, chemicals in the body that cause inflammation, pain, and fever. It is usually taken with or after food to reduce the risk of stomach upset.

Because these two medicines treat completely different conditions and work through different mechanisms, many people may need to take them at the same time—for example, a man using tadalafil for ED who also experiences pain requiring an NSAID. Understanding how they interact helps you use both medicines safely and effectively.

How do tadalafil and mefenamic acid interact in the body?

There is no major direct pharmacological interaction between tadalafil and mefenamic acid. They are metabolised by different pathways in the liver: tadalafil is primarily broken down by the enzyme CYP3A4, while mefenamic acid is metabolised by CYP2C9. This means they do not significantly interfere with each other's breakdown or blood levels [4][12].

However, both medicines can have cardiovascular effects that are worth being aware of. Tadalafil causes mild widening of blood vessels (vasodilation), which can lead to a small drop in blood pressure—usually not a problem for most men, but it can cause dizziness or light-headedness in some people. Mefenamic acid and other NSAIDs, when used regularly or at high doses, may slightly increase blood pressure and can reduce the effectiveness of some blood-pressure medicines. They may also increase the risk of cardiovascular events such as heart attack or stroke, particularly in people with existing heart disease or risk factors [12].

For most men taking tadalafil occasionally for ED and mefenamic acid occasionally for pain, the risk of a clinically significant interaction is low. The key is ensuring that your prescriber knows about all the medicines you take, including over-the-counter painkillers, so they can assess your individual cardiovascular health and advise on safe use.

What your prescriber will check

Before prescribing tadalafil, your doctor or pharmacist prescriber will ask about your current medicines, including any NSAIDs like mefenamic acid, ibuprofen, or naproxen. They will review your cardiovascular health, including blood pressure, history of heart disease, stroke, or other conditions that might be affected by either medicine. If you have high blood pressure, heart failure, or kidney problems, NSAIDs can worsen these conditions, and your prescriber will need to weigh the benefits and risks carefully. They will also check that you are not taking any medicines that are absolutely contraindicated with tadalafil, such as nitrates, nicorandil, or riociguat [2][4].

Can you take tadalafil and mefenamic acid together safely?

Yes, in most cases you can take tadalafil and mefenamic acid together, provided your prescriber has reviewed your full medical history and current medicines. No major interaction is commonly reported between these two medicines, and they are often used by the same person without problems [12].

That said, it is important to use both medicines exactly as prescribed or directed. Take mefenamic acid with or after food to protect your stomach, and do not exceed the recommended dose or duration (usually no more than seven days for pain). Use tadalafil only as needed for erectile dysfunction, and remember that it requires sexual stimulation to work—it is not an aphrodisiac and will not cause an erection on its own [4].

If you experience unusual symptoms such as severe dizziness, chest pain, fainting, or signs of an allergic reaction (rash, swelling, difficulty breathing), stop taking the medicines and seek medical help immediately. Always inform your GP, pharmacist, or prescriber if you start or stop any medicine, including over-the-counter painkillers, as this allows them to monitor for potential interactions and adjust your treatment if needed.

What about other NSAIDs and tadalafil interactions?

Mefenamic acid is just one of many NSAIDs available in the UK. Others include ibuprofen, naproxen, diclofenac, and aspirin (at anti-inflammatory doses). The interaction profile between tadalafil and NSAIDs is broadly similar across the class: no major direct drug interaction is expected, but the cardiovascular effects of NSAIDs—particularly when used regularly or at high doses—should be considered [12].

Low-dose aspirin (75mg daily) is commonly prescribed to reduce the risk of heart attack and stroke in people with cardiovascular disease. This dose is generally considered safe to take with tadalafil, and many men use both medicines together. However, higher doses of aspirin or other NSAIDs used for pain or inflammation carry a greater risk of gastrointestinal bleeding, especially if taken with other medicines that affect clotting or if you have a history of stomach ulcers.

If you are taking any NSAID regularly, whether prescribed or bought over the counter, always declare it during your consultation for ED treatment. Your prescriber will assess whether the combination is appropriate for you, taking into account your age, kidney function, blood pressure, and any other medicines you take. Never assume that because a medicine is available without prescription it is automatically safe to combine with tadalafil.

Practical tips for using NSAIDs with tadalafil

Use NSAIDs at the lowest effective dose for the shortest time needed to control your symptoms. Take them with or after food to reduce stomach irritation. Avoid taking multiple NSAIDs at the same time (for example, ibuprofen and mefenamic acid together), as this increases the risk of side effects without improving pain relief. Stay well hydrated, especially if you are taking NSAIDs for several days, as dehydration can increase the risk of kidney problems. If you need regular pain relief, speak to your GP about the safest option for your individual circumstances.

Tadalafil and mefenamic acid: what to watch for

Most men who take tadalafil and mefenamic acid together will not experience any problems, but it is sensible to be aware of potential warning signs. Common side effects of tadalafil include headache, indigestion, back pain, muscle aches, flushing, and nasal congestion. These are usually mild and short-lived. Mefenamic acid can cause stomach upset, nausea, diarrhoea, dizziness, and headache. Taking it with food helps reduce gastrointestinal side effects [4][12].

More serious but rare side effects of tadalafil include priapism (a painful erection lasting more than four hours), sudden loss of vision or hearing, and chest pain during sexual activity. If any of these occur, stop taking tadalafil and seek urgent medical help. NSAIDs like mefenamic acid can, in rare cases, cause serious gastrointestinal bleeding (signs include black or bloody stools, vomiting blood), allergic reactions, or worsening of asthma. Stop the medicine and contact your doctor or call 111 if you notice any of these symptoms.

If you feel unusually dizzy, light-headed, or faint after taking tadalafil and mefenamic acid together, sit or lie down until the feeling passes. This could indicate a drop in blood pressure. Avoid driving or operating machinery if you feel dizzy. If symptoms persist or worsen, seek medical advice. Always read the patient information leaflet that comes with each medicine and follow the instructions carefully.

Getting tadalafil and mefenamic acid safely in the UK

Tadalafil is a prescription-only medicine in the UK. At Cured Pharmacy, a GPhC-registered online pharmacy, you can request tadalafil after completing an online consultation. Your answers are reviewed by a UK-registered prescriber (doctor or pharmacist prescriber) who will check your suitability, including any current medicines such as mefenamic acid, before approving your treatment. If appropriate, your medicine is dispensed by our pharmacy team and delivered discreetly to your door [4].

Mefenamic acid is also prescription-only in the UK and is usually prescribed by your GP for short-term use. If you are already taking mefenamic acid and wish to start tadalafil for ED, or vice versa, make sure you declare both medicines during your consultation. Your prescriber will confirm that the combination is safe for you and provide tailored advice on how to use them together.

Cured Pharmacy offers a range of ED treatments, including generic and branded options. Tadalafil (generic Cialis) is available from £7.95 (first order with code Ednew: £6.36), and branded Cialis from £12.00 (first order with code Ednew: £9.60). Other options include sildenafil (generic Viagra) from £0.45 (first order with code Ednew: £0.36), vardenafil (generic Levitra) from £16.95 (first order with code Ednew: £13.56), and Spedra (avanafil) from £20.95 (first order with code Ednew: £16.76). All require a consultation and are dispensed only after prescriber approval. If you have any questions about tadalafil and mefenamic acid or any other medicine interaction, our pharmacy team is here to help.

When to see your GP

If you are experiencing new or worsening erectile dysfunction, it is important to see your GP for a full assessment. ED can be an early warning sign of underlying health conditions such as heart disease, diabetes, or high blood pressure [1][2]. Your GP can arrange tests, review your medicines, and refer you to a specialist if needed. If you need regular pain relief with NSAIDs like mefenamic acid, discuss this with your GP to ensure it is the safest option for you, especially if you have a history of stomach problems, kidney disease, or cardiovascular disease.

Scientific References

1. NHS. (n.d.). Erectile dysfunction (impotence). NHS website. https://www.nhs.uk/conditions/erection-problems-erectile-dysfunction/ [accessed 23 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 23 October 2026]
3. Joint Formulary Committee. (n.d.). Tadalafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/tadalafil/ [accessed 23 October 2026]
4. Electronic Medicines Compendium. (n.d.). Summaries of Product Characteristics and Patient Information Leaflets. https://www.medicines.org.uk/emc/ [accessed 23 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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