Tadalafil and Oxybutynin: Can You Take Them Together?

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Tadalafil and Oxybutynin: Understanding the Interaction

Published: 24 October 2026

Many men wonder whether tadalafil and oxybutynin can be taken together safely. The good news is that no major direct interaction is commonly reported between tadalafil (a medicine for erectile dysfunction) and oxybutynin (used for overactive bladder), but both medicines can cause certain side effects that may overlap, so your prescriber will review your full medical history before approving treatment [2][4].

What is tadalafil and oxybutynin?

Tadalafil is a phosphodiesterase type 5 (PDE5) inhibitor licensed in the UK to treat erectile dysfunction (ED). It works by relaxing blood vessels in the penis, allowing increased blood flow when you are sexually aroused [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) for men who prefer spontaneity [4]. Brand names include Cialis, and generic tadalafil is widely available at lower cost.

Oxybutynin is an antimuscarinic (anticholinergic) medicine used to treat overactive bladder syndrome and urinary incontinence [12]. It works by relaxing the bladder muscle, reducing the urge to urinate frequently or urgently. Oxybutynin is available as immediate-release tablets, modified-release tablets, or a transdermal patch. Common side effects include dry mouth, constipation, blurred vision, and dizziness [12]. Because both tadalafil and oxybutynin can affect blood pressure and cause dizziness, your prescriber will check whether the combination is suitable for you.

Do tadalafil and oxybutynin interact with each other?

There is no major direct pharmacological interaction between tadalafil and oxybutynin reported in standard UK prescribing references [2][4][12]. They work through different mechanisms: tadalafil affects blood flow by inhibiting PDE5, while oxybutynin blocks muscarinic receptors in the bladder. Neither medicine is known to significantly alter the metabolism or effectiveness of the other.

However, both medicines can cause overlapping side effects that may be more noticeable when taken together. Tadalafil can lower blood pressure slightly and may cause dizziness or headache, especially when you first start treatment [4]. Oxybutynin can also cause dizziness, drowsiness, and blurred vision, particularly in older adults [12]. If you experience increased dizziness, light-headedness when standing, or difficulty concentrating, speak to your GP or pharmacist. Your prescriber will assess your overall medication list, blood pressure, and any other health conditions before approving tadalafil, to ensure the combination is safe for you.

How the interaction is managed

During your online consultation at Cured Pharmacy, the prescriber will ask about all your current medicines, including oxybutynin, and review your medical history. If you are stable on oxybutynin and have no other contraindications, tadalafil can usually be prescribed safely [2]. You may be advised to start on a lower dose of tadalafil (such as 10 mg on-demand or 2.5 mg daily) to minimise the risk of side effects. Always take tadalafil and oxybutynin exactly as prescribed, and do not adjust doses without consulting your prescriber.

What does your prescriber check before approving tadalafil and oxybutynin together?

Before prescribing tadalafil, your clinician will review your full medication list to identify any medicines that could interact dangerously. Tadalafil must never be taken with nitrates (such as GTN spray, isosorbide mononitrate), nicorandil, riociguat, or recreational drugs known as 'poppers' (amyl or alkyl nitrites), because the combination can cause a severe and potentially life-threatening drop in blood pressure [4]. You should also not take tadalafil with another PDE5 inhibitor (such as sildenafil or vardenafil) at the same time.

Your prescriber will ask about your blood pressure, heart health, and any history of stroke, heart attack, or severe liver or kidney disease [2][4]. They will also check whether you take alpha-blockers (such as tamsulosin or doxazosin) for prostate symptoms, as these can interact with tadalafil and increase the risk of dizziness or fainting. If you are on an alpha-blocker, you should be stable on that medicine before starting tadalafil, and a lower starting dose of tadalafil is usually recommended [4]. Oxybutynin itself does not contraindicate tadalafil, but the prescriber will consider your overall health picture, including any history of glaucoma, urinary retention, or cognitive impairment, which may be relevant to oxybutynin use.

Practical advice for taking tadalafil and oxybutynin safely

If you have been prescribed both tadalafil and oxybutynin, take each medicine exactly as directed. Tadalafil on-demand tablets (10 mg or 20 mg) should be taken at least 30 minutes before sexual activity, and you should not take more than one dose in 24 hours [4]. Daily tadalafil (2.5 mg or 5 mg) is taken once a day at roughly the same time, regardless of when you plan to have sex. Oxybutynin is usually taken two to three times a day (immediate-release) or once daily (modified-release); follow the instructions on your prescription label.

Be aware of side effects that may be more noticeable when taking both medicines. Common side effects of tadalafil include headache, indigestion, back pain, muscle aches, flushing, and nasal congestion [4]. Oxybutynin commonly causes dry mouth, constipation, blurred vision, and dizziness [12]. Drink plenty of water, avoid heavy alcohol (which can worsen ED and increase dizziness), and rise slowly from sitting or lying to reduce the risk of light-headedness. If you experience severe dizziness, fainting, chest pain during sex, or an erection lasting more than four hours, seek urgent medical help.

When to contact your GP or pharmacist

Contact your GP or pharmacist if you notice new or worsening side effects after starting tadalafil, such as persistent dizziness, visual disturbances, or difficulty passing urine. Do not stop oxybutynin suddenly without medical advice, as your bladder symptoms may return. If tadalafil is not effective for you, your prescriber can discuss alternative PDE5 inhibitors (such as sildenafil, vardenafil, or avanafil) or other treatment options [2]. Always inform any healthcare professional you see (including dentists and hospital doctors) that you are taking both tadalafil and oxybutynin.

Other medicines that interact with tadalafil

Beyond oxybutynin, several other medicines can interact with tadalafil and require careful prescriber review. Alpha-blockers (doxazosin, tamsulosin, alfuzosin, terazosin, prazosin, silodosin, indoramin) are commonly prescribed for benign prostatic hyperplasia (enlarged prostate) and can cause a significant drop in blood pressure when combined with tadalafil [4]. If you take an alpha-blocker, you must be stable on that medicine, and your prescriber will start you on the lowest dose of tadalafil.

Potent CYP3A4 inhibitors—medicines that slow the breakdown of tadalafil in the liver—can raise tadalafil levels in your blood and increase the risk of side effects. These include ritonavir and cobicistat (used in HIV treatment), Paxlovid (nirmatrelvir with ritonavir, used for COVID-19), ketoconazole and itraconazole (antifungal medicines), and clarithromycin (an antibiotic) [4]. If you take any of these, your prescriber will reduce the maximum dose of tadalafil or advise you to avoid it temporarily. Conversely, CYP3A4 inducers such as rifampicin, carbamazepine, phenytoin, and St John's wort can make tadalafil less effective by speeding up its breakdown [4]. Grapefruit juice can also raise tadalafil levels and should be avoided or limited.

How to get tadalafil and oxybutynin prescribed online

At Cured Pharmacy, you can request tadalafil through a confidential online consultation. A UK-registered prescriber will review your medical history, current medicines (including oxybutynin), and overall health to ensure tadalafil is safe and suitable for you. Prescription medicines are only supplied after this clinical assessment. If approved, your tadalafil will be dispensed by our GPhC-registered pharmacy (GPhC 9012511) and delivered discreetly to your door.

We offer a range of tadalafil products, including generic tadalafil tablets and branded Cialis, at transparent prices. Generic tadalafil is available from £7.95 for on-demand treatment (first order £6.36 with code Ednew), and branded Cialis from £12.00 (first order £9.60 with code Ednew). Tadalafil 20 mg (Teva) is priced at £9.99 (first order £7.99 with code Ednew), and Avarante (tadalafil) 10 mg at £11.49 (first order £9.19 with code Ednew). If you have new or worsening erectile dysfunction, we encourage you to see your GP first, as ED can be an early sign of heart disease or diabetes [1][2]. Our service is designed to provide convenient, ongoing access to treatment once your condition has been assessed.

Alternative ED treatments available

If tadalafil is not suitable or effective for you, other PDE5 inhibitors are available. Sildenafil (generic Viagra) is taken about one hour before sex and is available from £0.45 per tablet (first order £0.36 with code Ednew). Vardenafil (generic Levitra) works in 25–60 minutes and costs £16.95 (first order £13.56 with code Ednew). Avanafil (Spedra) is the fastest-acting option, working in 15–30 minutes, priced at £20.95 (first order £16.76 with code Ednew) [6][11]. All PDE5 inhibitors require sexual stimulation to work and share similar contraindications and interactions. Your prescriber will help you choose the most appropriate option based on your lifestyle, health, and preferences.

Scientific References

1. NHS. (n.d.). Erectile dysfunction (impotence). NHS website. https://www.nhs.uk/conditions/erection-problems-erectile-dysfunction/ [accessed 24 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 24 October 2026]
3. Joint Formulary Committee. (n.d.). Tadalafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/tadalafil/ [accessed 24 October 2026]
4. Electronic Medicines Compendium. (n.d.). Summaries of Product Characteristics and Patient Information Leaflets. https://www.medicines.org.uk/emc/ [accessed 24 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.