Tadalafil and Ciclosporin: Can They Be Taken Together?

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What is tadalafil and ciclosporin?

Tadalafil is a phosphodiesterase type 5 (PDE5) inhibitor licensed in the UK to treat erectile dysfunction. It works by relaxing blood vessels in the penis, allowing increased blood flow during sexual stimulation. Tadalafil is available as an on-demand treatment (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 option (2.5 mg or 5 mg). It requires sexual arousal to work and does not cause spontaneous erections [4].

Ciclosporin (also spelled cyclosporine) is an immunosuppressant medicine that reduces the activity of your immune system. It is most commonly prescribed to prevent organ rejection after kidney, liver, or heart transplants, and is also used to treat severe psoriasis, rheumatoid arthritis, and certain inflammatory eye conditions. Ciclosporin is taken long-term and requires regular blood tests to monitor levels and kidney function [12].

Both medicines are metabolised (broken down) by the same liver enzyme system, CYP3A4, which is why they interact. When ciclosporin blocks this enzyme, tadalafil is cleared from the body more slowly, leading to higher blood levels and a greater chance of side effects.

How do tadalafil and ciclosporin interact?

Ciclosporin is a potent inhibitor of the CYP3A4 enzyme in the liver, which is responsible for breaking down tadalafil. When you take ciclosporin, it slows the metabolism of tadalafil, causing tadalafil to accumulate in your bloodstream at higher concentrations than usual. This pharmacokinetic interaction means that a standard dose of tadalafil can have a stronger and longer-lasting effect when taken alongside ciclosporin [4].

The increased tadalafil levels raise the risk of dose-related side effects, including headache, facial flushing, indigestion, nasal congestion, back pain, and muscle aches. More importantly, because tadalafil lowers blood pressure by dilating blood vessels, higher levels can lead to symptomatic hypotension (low blood pressure), causing dizziness, light-headedness, or fainting—particularly when standing up quickly. This risk is greater if you also take other blood-pressure-lowering medicines or alpha-blockers [4].

The interaction is well-recognised and manageable through dose adjustment. The British National Formulary and the Summary of Product Characteristics for tadalafil both provide clear guidance: the maximum recommended dose of tadalafil when taken with potent CYP3A4 inhibitors like ciclosporin is 10 mg in any 72-hour period [4][12]. Your prescriber will take your ciclosporin use into account during the consultation and adjust your tadalafil dose accordingly.

Why dose adjustment is essential

Because ciclosporin can more than double the exposure to tadalafil, taking a full 20 mg dose could result in side effects equivalent to taking 40 mg or more. This is why the maximum dose is capped at 10 mg, and many prescribers will start you on an even lower dose to assess your tolerance. Dose adjustment minimises the risk of adverse effects while still allowing tadalafil to work effectively for erectile dysfunction. Never increase your tadalafil dose without consulting your prescriber if you are taking ciclosporin.

What your prescriber checks before prescribing tadalafil with ciclosporin

When you request tadalafil through an online consultation at Cured Pharmacy, you will be asked to list all your current medicines, including ciclosporin and any other immunosuppressants. A UK-registered prescriber will review your medical history, current medications, and any other conditions that might affect the safety of tadalafil. This review is mandatory for all prescription medicines and ensures that the dose and formulation are appropriate for you [2].

Your prescriber will check for other interacting medicines, particularly other CYP3A4 inhibitors (such as certain antifungals or antibiotics), alpha-blockers (used for prostate symptoms or high blood pressure), and nitrates or nicorandil (used for angina), which are absolutely contraindicated with tadalafil. They will also assess your cardiovascular health, as erectile dysfunction can be an early warning sign of heart disease or diabetes, and sexual activity itself carries a small cardiovascular demand [1][2].

If you are stable on ciclosporin and have no other contraindications, your prescriber will typically recommend a starting dose of tadalafil 10 mg on-demand, to be taken no more than once every 72 hours. They may advise starting with 5 mg if you have other risk factors for low blood pressure or are taking additional interacting medicines. You should never take tadalafil more frequently than prescribed, and you must not combine it with another PDE5 inhibitor [4].

What you need to know

• Tadalafil and ciclosporin can be taken together with dose adjustment—maximum 10 mg tadalafil every 72 hours.
• Ciclosporin raises tadalafil levels by slowing its breakdown, increasing the risk of side effects like low blood pressure.
• Your prescriber will review all your medicines and adjust your tadalafil dose to keep treatment safe and effective.
• Always tell your transplant team or specialist that you are taking tadalafil alongside ciclosporin.
• Seek urgent help if you have chest pain, an erection over four hours, or sudden vision or hearing loss.

Practical advice for taking tadalafil and ciclosporin together

If you have been prescribed tadalafil while taking ciclosporin, follow your prescriber's dosing instructions exactly. Do not exceed 10 mg of tadalafil in any 72-hour period, even if you feel the lower dose is not as effective as you hoped. Taking more than the recommended dose significantly increases the risk of side effects, including dangerously low blood pressure. If the prescribed dose does not work well for you, contact your prescriber to discuss alternatives rather than increasing the dose yourself [4].

Take tadalafil at least 30 minutes before planned sexual activity. Because the interaction with ciclosporin prolongs tadalafil's presence in your body, the effects may last longer than the usual 36 hours, so be mindful of this when planning. Avoid drinking large amounts of alcohol, as this can worsen erectile dysfunction and add to the blood-pressure-lowering effect of tadalafil, increasing the risk of dizziness or fainting. Grapefruit juice can also raise tadalafil levels further and should be avoided [4].

Monitor yourself for side effects, especially during the first few doses. Mild headache, flushing, or nasal congestion are common and usually settle with continued use. However, if you experience severe dizziness, fainting, chest pain during sex, or an erection lasting more than four hours (priapism), seek urgent medical help. If you develop sudden vision or hearing loss, stop taking tadalafil immediately and contact a doctor the same day. Always inform any healthcare professional treating you that you are taking both ciclosporin and tadalafil.

Reporting side effects and monitoring

Because you are taking ciclosporin, you will already be under regular medical review with blood tests to monitor ciclosporin levels and kidney function. Make sure your transplant team or rheumatologist knows you are taking tadalafil, as they may want to check for any additional effects on blood pressure or kidney function. Report any new or worsening side effects to your GP, prescriber, or transplant team promptly. You can also report side effects directly via the Yellow Card Scheme at yellowcard.mhra.gov.uk.

Other medicines that interact with tadalafil in a similar way

Ciclosporin is not the only medicine that inhibits CYP3A4 and raises tadalafil levels. Other potent CYP3A4 inhibitors include ritonavir and cobicistat (used in HIV treatment), the COVID-19 antiviral Paxlovid (nirmatrelvir with ritonavir), and certain antifungal medicines such as ketoconazole and itraconazole. The macrolide antibiotic clarithromycin is also a strong inhibitor. If you are prescribed any of these medicines, the same dose restrictions apply: a maximum of 10 mg tadalafil in 72 hours, or avoidance altogether depending on the specific medicine and your overall risk profile [4][12].

Tacrolimus, another immunosuppressant often used alongside or instead of ciclosporin after transplants, is also metabolised by CYP3A4. While tacrolimus itself is a substrate rather than a strong inhibitor, the combination with tadalafil should still be reviewed by your prescriber, as both medicines can affect blood pressure and kidney function. Always declare tacrolimus and any other immunosuppressants during your consultation [12].

Conversely, medicines that induce (speed up) CYP3A4—such as rifampicin, carbamazepine, phenytoin, and St John's wort—can reduce tadalafil levels and make it less effective. If you are taking any of these, your prescriber may need to adjust your tadalafil dose upwards or consider an alternative ED treatment. The key message is that every medicine you take can potentially interact, which is why a thorough medication review is essential before starting tadalafil [4].

When to get urgent help

• Erection lasting more than 4 hours (priapism)—go to A&E immediately to prevent permanent damage
• Sudden loss of vision in one or both eyes—stop tadalafil and seek same-day medical advice
• Chest pain during or after sex—call 999; do not take nitrate medicines (GTN) if you have used tadalafil
• Severe dizziness, fainting, or feeling light-headed—sit or lie down and seek medical help if it does not resolve quickly
• Sudden decrease or loss of hearing, sometimes with ringing in the ears—stop tadalafil and contact your GP the same day

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

Alternatives and when to seek further advice

If the dose restriction imposed by the tadalafil and ciclosporin interaction limits the effectiveness of your ED treatment, or if you experience troublesome side effects, discuss alternatives with your prescriber. Other PDE5 inhibitors—sildenafil (Viagra), vardenafil (Levitra), and avanafil (Spedra)—are also affected by CYP3A4 inhibitors, though to varying degrees. Sildenafil may be used at a reduced starting dose (25 mg), while vardenafil and avanafil are generally avoided or contraindicated with potent CYP3A4 inhibitors [3][5][6].

Non-oral treatments for erectile dysfunction, such as vacuum erection devices, are not affected by drug interactions and may be a suitable option if oral medicines are problematic. Alprostadil, available as a urethral cream (Vitaros) or injection (Caverject), works by a different mechanism and does not interact with ciclosporin, though it requires careful technique and carries its own side effects [7]. Your GP or a specialist can discuss these alternatives with you.

If you develop new erectile dysfunction while taking ciclosporin, it is important to see your GP for a full assessment. ED can be an early sign of cardiovascular disease or diabetes, both of which are more common in people taking long-term immunosuppressants. Your GP can check for underlying causes, review your overall medication regimen, and refer you to a specialist if needed. Do not stop or change your ciclosporin dose without medical advice, as this could risk organ rejection or disease flare [1][2].

When tadalafil is not suitable

Tadalafil is not suitable for everyone. It must not be taken with nitrates (such as GTN spray or isosorbide mononitrate), nicorandil, riociguat, or recreational drugs called poppers (amyl or alkyl nitrites), as the combination can cause a dangerous drop in blood pressure. It is also contraindicated if you have had a recent heart attack or stroke, have unstable angina, severe heart failure, very low blood pressure, or a history of non-arteritic anterior ischaemic optic neuropathy (sudden vision loss). Your prescriber will screen for these conditions during the consultation [4].