Tadalafil and Rifampicin: Can They Be Taken Together?

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Key takeaways

• Rifampicin can make tadalafil much less effective by speeding up how quickly your body breaks it down
• The combination is not dangerous, but tadalafil may not work as expected while you're taking rifampicin
• All PDE5 inhibitors (sildenafil, vardenafil, avanafil) are affected by rifampicin in a similar way
• Never stop rifampicin to make tadalafil work – always complete your antibiotic course as prescribed
• Tadalafil should work normally two to three weeks after finishing rifampicin treatment

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 PDE5 inhibitors, which work by relaxing the blood vessels in the penis, allowing more blood to flow in when you're sexually aroused [4]. Unlike some other ED treatments, tadalafil can work for up to 36 hours after taking it, which is why it's 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 tablets (2.5mg or 5mg) taken at the same time each day [4]. The on-demand option is more popular and allows for spontaneity, as the effect can last throughout the weekend. Both forms require sexual stimulation to work – tadalafil won't cause an erection on its own.

At Cured Pharmacy, tadalafil is available after an online consultation with a UK-registered prescriber who will check your medical history and current medicines to ensure it's safe and suitable for you. Common brand names include Cialis (the original branded version) and various generic versions that contain exactly the same active ingredient.

What is rifampicin and why is it prescribed?

Rifampicin (also spelled rifampin in some countries) is a powerful antibiotic primarily used to treat tuberculosis (TB), a serious bacterial infection that usually affects the lungs [12]. It's also prescribed for other infections including leprosy, certain bone infections, and to prevent meningitis in people who have been in close contact with someone who has the disease. Rifampicin is often taken for several months as part of a combination treatment for TB.

This antibiotic works by killing the bacteria that cause these infections, but it also has a significant effect on how your liver processes other medicines. Rifampicin is what's known as a 'CYP3A4 inducer' – it speeds up the activity of enzymes in your liver that break down many medicines, including tadalafil and other erectile dysfunction treatments [3][4]. This means medicines are cleared from your body more quickly than usual.

Because rifampicin is used to treat serious infections, it's important never to stop taking it without your doctor's advice, even if it affects other medicines you're taking. Your healthcare team can work together to find the best approach to managing both your infection and any other health concerns, including erectile dysfunction.

How long does rifampicin affect other medicines?

Rifampicin's effect on liver enzymes can last for several weeks after you stop taking it. The enzyme-inducing effect builds up over the first few weeks of treatment and can continue for up to two to three weeks after your last dose [12]. This means that even after finishing your rifampicin course, tadalafil and other medicines may still be broken down more quickly than normal for a short time. Your prescriber will take this into account when advising you about erectile dysfunction treatment during and after rifampicin therapy.

At a glance

How does rifampicin interact with tadalafil?

The interaction between tadalafil and rifampicin is significant because rifampicin speeds up the breakdown of tadalafil in your liver. This means that tadalafil is cleared from your body much more quickly than it would be normally, reducing both the strength and duration of its effect [4]. In practical terms, if you take a standard dose of tadalafil while on rifampicin, you may find it doesn't work as well, or doesn't work at all.

This happens through a process called enzyme induction. Tadalafil is normally broken down by an enzyme called CYP3A4 in your liver. Rifampicin dramatically increases the activity of this enzyme, so tadalafil is metabolised and removed from your bloodstream much faster [3][4]. Studies have shown that enzyme inducers like rifampicin can reduce the blood levels of tadalafil by a substantial amount, potentially making the medicine ineffective at standard doses.

It's important to understand that this interaction doesn't make the combination dangerous in terms of serious side effects – it's not like the life-threatening interaction between tadalafil and nitrate medicines. The main concern is reduced effectiveness. However, simply increasing the dose of tadalafil isn't always the answer, as higher doses carry a greater risk of side effects. Your prescriber will need to carefully consider the best approach for your individual situation.

What does your prescriber check before prescribing tadalafil with rifampicin?

When you complete an online consultation at Cured Pharmacy, the UK-registered prescriber will ask detailed questions about all your current medicines, including rifampicin. They'll want to know how long you've been taking rifampicin, what dose you're on, and how long your treatment is expected to continue. This information helps them decide whether tadalafil is likely to be effective for you, or whether an alternative approach might be better.

Your prescriber will also review your medical history to check for any other conditions that might affect erectile dysfunction or interact with treatment. They'll consider whether your ED started before or after beginning rifampicin – sometimes the underlying infection or the stress of serious illness can contribute to erectile problems [1][2]. If your ED is new, they may recommend seeing your GP for a full assessment, as erectile dysfunction can be an early warning sign of heart disease or diabetes [1].

The prescriber will also check that you're not taking any medicines that are absolutely contraindicated with tadalafil, such as nitrates (GTN spray, isosorbide mononitrate), nicorandil, riociguat, or recreational drugs called 'poppers' [4]. These combinations can cause a dangerous drop in blood pressure and must never be taken together. They'll also review any blood pressure medicines or alpha-blockers you're taking, as these require careful dose adjustment.

Can the tadalafil dose be adjusted?

In theory, increasing the dose of tadalafil could help overcome the reduced effectiveness caused by rifampicin. However, this approach isn't always recommended because higher doses increase the risk of side effects such as headaches, indigestion, back pain, and flushing [4]. Your prescriber will weigh up the potential benefits against the risks for your individual circumstances. In some cases, they may suggest waiting until you've finished your rifampicin course before starting erectile dysfunction treatment, or they may recommend a different type of treatment altogether.

What are the alternatives if tadalafil and rifampicin don't work well together?

If you're taking rifampicin and need treatment for erectile dysfunction, there are several options your prescriber might consider. Other PDE5 inhibitors – sildenafil (Viagra), vardenafil (Levitra), and avanafil (Spedra) – are all affected by rifampicin in a similar way, as they're all broken down by the same liver enzyme [3][5][6]. This means switching to a different tablet in the same family may not solve the problem.

One option is to wait until you've completed your rifampicin treatment before starting or restarting erectile dysfunction medication. Because rifampicin is usually prescribed for serious infections that need to be fully treated, this is often the safest approach. Once you've finished the rifampicin course and the enzyme-inducing effect has worn off (usually two to three weeks later), tadalafil and other PDE5 inhibitors should work normally again [12].

Alternative treatments that don't rely on tablets include Eroxon, a topical gel that works locally rather than being absorbed into the bloodstream, so it's not affected by rifampicin. Prescription options such as Vitaros (alprostadil cream) or Caverject (alprostadil injection) work through a different mechanism and may also be less affected, though these require specialist assessment [7]. Your GP or a specialist can discuss these options with you if oral treatments aren't suitable while you're on rifampicin.

Practical advice for managing tadalafil and rifampicin together

If you're currently taking rifampicin and considering treatment for erectile dysfunction, the most important step is to be completely honest during your online consultation. Declare all your current medicines, including antibiotics, and mention if you've recently finished a course of rifampicin. This allows the prescriber to give you accurate advice about whether tadalafil is likely to work for you, or whether you should wait or try a different approach.

Never stop taking rifampicin to make tadalafil work better. Rifampicin is prescribed for serious infections that need complete treatment – stopping early can lead to treatment failure, drug resistance, and serious health consequences [12]. Similarly, don't increase your tadalafil dose without medical advice, as this increases the risk of side effects such as severe headaches, dizziness, or prolonged erections (priapism), which require urgent medical attention.

Keep all your healthcare professionals informed. If your GP or TB specialist doesn't know you're taking tadalafil, tell them. If you're ordering ED treatment online, make sure the prescriber knows about your rifampicin. Good communication between your healthcare team ensures you receive safe, effective care. Remember that erectile dysfunction is very common and nothing to be embarrassed about – around half of men aged 40–70 experience it to some degree [10], and your doctors are there to help you manage all aspects of your health.

What about other CYP3A4 inducers?

Rifampicin isn't the only medicine that can reduce tadalafil's effectiveness. Other enzyme inducers include carbamazepine and phenytoin (used for epilepsy), and the herbal remedy St John's wort (often taken for low mood) [3][4]. If you're taking any of these, the same principles apply: they may make tadalafil less effective, and you should discuss this with your prescriber. Never take St John's wort alongside prescription medicines without medical advice, as it interacts with many treatments.

When to get urgent help

• Erection lasting more than 4 hours (priapism) – go to A&E immediately
• Sudden loss of vision in one or both eyes – stop tadalafil and seek urgent medical help
• Chest pain during or after sex – call 999; do not take nitrate medicines if you've used tadalafil recently
• Severe dizziness, fainting, or very fast heartbeat after taking tadalafil – seek same-day medical advice
• Allergic reaction (rash, swelling of face or throat, difficulty breathing) – call 999

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