Tadalafil and Digoxin: Can They Be Taken Together?

Tadalafil and Digoxin: Understanding the Interaction and What It Means for You

Published: 20 October 2026

If you're taking digoxin for a heart condition and considering tadalafil (Cialis) for erectile dysfunction, you may be wondering whether tadalafil and digoxin can be taken together safely. The good news is that tadalafil is not contraindicated with digoxin, meaning the two medicines can usually be used together under medical supervision. However, because both medicines affect the cardiovascular system, your prescriber will need to review your full medical history and current heart health to ensure the combination is appropriate for you.

What Is Tadalafil and How Does It Work?

Tadalafil is a prescription medicine used to treat erectile dysfunction (ED) in men. It belongs to a group of medicines called phosphodiesterase type 5 (PDE5) inhibitors, which work by relaxing the blood vessels in the penis, allowing increased blood flow when you are sexually aroused [4]. Tadalafil is the active ingredient in branded Cialis and is also available as a generic medicine at a lower cost.

Tadalafil is available in two forms: on-demand tablets (10mg or 20mg) taken at least 30 minutes before sexual activity, with effects lasting up to 36 hours, and daily tablets (2.5mg or 5mg) taken once a day to allow for spontaneity [4]. All PDE5 inhibitors, including tadalafil, require sexual stimulation to work—they do not cause an automatic erection.

Because tadalafil widens blood vessels, it can cause a small drop in blood pressure. This effect is usually mild in healthy men, but it becomes more important when tadalafil is taken alongside other medicines that affect the heart or blood pressure, such as digoxin [4].

What Is Digoxin and Why Is It Prescribed?

Digoxin is a prescription medicine used to treat certain heart conditions, particularly atrial fibrillation (an irregular heartbeat) and heart failure. It works by slowing down the heart rate and making the heart beat more strongly and regularly. Digoxin has been used for many decades and remains an important treatment for people whose heart rhythm or pumping function needs support.

Digoxin has a narrow therapeutic window, which means the difference between an effective dose and a dose that causes side effects is quite small. For this reason, people taking digoxin often have regular blood tests to check their digoxin levels and kidney function. Common side effects of digoxin include nausea, dizziness, visual disturbances (such as seeing yellow halos), and fatigue.

Because digoxin is used to manage heart conditions, anyone taking it will need a careful assessment before starting any new medicine that affects the cardiovascular system, including treatments for erectile dysfunction. Your prescriber will want to ensure your heart condition is stable and that adding tadalafil will not cause any problems.

Can Tadalafil and Digoxin Be Taken Together?

Yes, tadalafil and digoxin can generally be taken together, and there is no absolute contraindication between the two medicines. Unlike nitrates, nicorandil, or riociguat—which must never be combined with PDE5 inhibitors like tadalafil—digoxin does not cause a dangerous interaction that would prevent you from using tadalafil for erectile dysfunction [4].

However, this does not mean the combination is automatically safe for everyone. Because digoxin is prescribed for heart conditions, your prescriber will need to assess whether your heart is healthy enough for sexual activity and whether tadalafil is appropriate given your overall cardiovascular health. Sexual activity itself places demands on the heart, and tadalafil's mild blood-pressure-lowering effect must be considered in the context of your heart condition.

During your online consultation at Cured Pharmacy, the prescriber will review your current medicines, including digoxin, and ask about your heart condition, symptoms, and any recent changes in your health. This ensures that tadalafil is prescribed safely and at the right dose for you. You should never start tadalafil without a prescriber's review if you are taking digoxin or any other heart medicine.

Why the Combination Requires Medical Review

The main reason tadalafil and digoxin require careful assessment is that both medicines are used in people with cardiovascular conditions. Tadalafil can cause a small drop in blood pressure, and while this is usually well tolerated, it may be more noticeable in someone whose heart function is already compromised. Additionally, if you are taking other heart or blood pressure medicines alongside digoxin, the combined effect on blood pressure needs to be considered [4].

Your prescriber will also check that your heart condition is stable. Tadalafil is not suitable for men with severe heart failure, unstable angina, or those who have had a heart attack or stroke in the past six months [4]. If your digoxin is controlling your heart rhythm well and you have no recent cardiac events, tadalafil may be a safe and effective option for you.

How Tadalafil and Digoxin Interact in the Body

From a pharmacological perspective, tadalafil and digoxin do not have a direct drug-to-drug interaction that significantly alters the levels or effects of either medicine. Tadalafil is metabolised primarily by the liver enzyme CYP3A4, while digoxin is eliminated mainly by the kidneys and is not significantly metabolised by liver enzymes [4]. This means that tadalafil does not interfere with how your body processes digoxin, and digoxin does not affect tadalafil levels.

The key consideration is the physiological effect of tadalafil on blood pressure and heart function. Tadalafil relaxes blood vessels throughout the body, which can lead to a modest reduction in blood pressure. In most men, this drop is small and causes no symptoms. However, in someone with a heart condition managed by digoxin, even a small change in blood pressure may be more noticeable, particularly if other blood-pressure-lowering medicines are also being taken.

This is why your prescriber will ask about all your current medicines, not just digoxin. If you are also taking medicines such as beta-blockers, ACE inhibitors, or diuretics (water tablets), the combined blood-pressure-lowering effect will be taken into account when deciding whether tadalafil is suitable and what dose to prescribe [4].

What Your Prescriber Will Check Before Prescribing Tadalafil

When you request tadalafil through Cured Pharmacy's online consultation, the UK-registered prescriber will ask a series of questions to ensure the medicine is safe and appropriate for you. If you are taking digoxin, the prescriber will want to know why it was prescribed, how long you have been taking it, and whether your heart condition is stable. You will also be asked about any symptoms such as chest pain, breathlessness, dizziness, or palpitations.

The prescriber will review all your current medicines to check for interactions. As well as digoxin, they will look for other heart or blood pressure medicines, and they will specifically check that you are not taking nitrates, nicorandil, or riociguat, which are absolute contraindications with tadalafil [4]. You will also be asked about your general health, including conditions such as diabetes, high cholesterol, kidney or liver problems, and any history of stroke or heart attack.

If your heart condition is well controlled and there are no contraindications, the prescriber may approve tadalafil, often starting with a lower dose to see how you respond. You should always be honest and thorough when completing the consultation, as missing information could lead to an unsafe prescription.

Starting on a Lower Dose

For men taking digoxin or other heart medicines, the prescriber may recommend starting with a lower dose of tadalafil—such as 10mg on-demand or 2.5mg daily—to minimise the risk of side effects and assess how well you tolerate the medicine [4]. If the lower dose is effective and well tolerated, it can be continued. If a stronger effect is needed and there are no problems, the dose may be increased after discussion with your prescriber.

This cautious approach is standard practice for anyone with cardiovascular conditions and helps ensure that tadalafil is both safe and effective for you.

Practical Advice for Taking Tadalafil and Digoxin Safely

If you are prescribed tadalafil while taking digoxin, there are several practical steps you can take to use the medicine safely. First, take tadalafil exactly as prescribed—do not take more than the recommended dose or take it more often than once a day (for on-demand tablets) [4]. If you are using daily tadalafil, take it at the same time each day to maintain steady levels in your body.

Be aware of how you feel after taking tadalafil, particularly the first few times. Common side effects include headache, indigestion, back pain, and flushing, which are usually mild and temporary [4]. However, if you experience dizziness, light-headedness, or feel faint—especially when standing up—this may be a sign that your blood pressure has dropped too much. Sit or lie down until the feeling passes, and let your prescriber know if it happens again.

Avoid drinking large amounts of alcohol when taking tadalafil, as alcohol can lower blood pressure further and make side effects more likely. Grapefruit juice can increase tadalafil levels in the blood and should be avoided [4]. Continue taking your digoxin and other heart medicines exactly as prescribed by your doctor—do not stop or change any medicine without medical advice, even if you start tadalafil.

If you develop chest pain during or after sexual activity, stop and seek urgent medical help. Do not take nitrate medicines (such as GTN spray) if you have used tadalafil in the past 48 hours, as this combination can cause a dangerous drop in blood pressure [4]. Make sure any healthcare professional treating you knows you are taking tadalafil.

When to Seek Medical Advice

You should contact your GP or prescriber if you experience persistent dizziness, fainting, or any new or worsening symptoms after starting tadalafil. Seek urgent medical help (call 999 or go to A&E) if you have chest pain during sex, an erection lasting more than four hours (priapism), or sudden loss of vision or hearing [4]. These are rare but serious side effects that require immediate attention.

If your heart condition changes—for example, if your doctor adjusts your digoxin dose, adds a new heart medicine, or if you are admitted to hospital—let your tadalafil prescriber know, as your ED treatment may need to be reviewed.

Scientific References

1. NHS. (n.d.). Erectile dysfunction (impotence). NHS website. https://www.nhs.uk/conditions/erection-problems-erectile-dysfunction/ [accessed 20 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 20 October 2026]
3. Joint Formulary Committee. (n.d.). Tadalafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/tadalafil/ [accessed 20 October 2026]
4. Electronic Medicines Compendium. (n.d.). Summaries of Product Characteristics and Patient Information Leaflets. https://www.medicines.org.uk/emc/ [accessed 20 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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