Sildenafil and Rifampicin: Can You Take Them Together?

Sildenafil and Rifampicin: Understanding the Interaction

Published: 16 October 2026

Sildenafil and rifampicin can be taken together, but rifampicin significantly reduces how well sildenafil works for erectile dysfunction. Rifampicin is a powerful antibiotic used mainly to treat tuberculosis (TB) and some other serious bacterial infections. It speeds up the breakdown of many medicines in your body, including sildenafil, which means sildenafil may not be effective enough to help with erections. Your prescriber will need to review your treatment and may suggest a higher dose, a different ED medicine, or waiting until your rifampicin course is finished.

What is sildenafil and rifampicin used for?

Sildenafil (also known as Viagra) is a prescription medicine for erectile dysfunction (ED). It belongs to a group of medicines called PDE5 inhibitors, which work by relaxing blood vessels in the penis to help you get and keep an erection when you are sexually aroused [3]. Sildenafil is usually taken about one hour before sex, at doses of 25mg, 50mg or 100mg, and works for around four to six hours. It does not work automatically—you still need sexual stimulation for it to be effective [1].

Rifampicin is a powerful antibiotic prescribed for tuberculosis (TB), some types of meningitis, and certain other serious bacterial infections. It is often taken daily for several months as part of combination therapy. Rifampicin is very effective at killing bacteria, but it also affects how your liver processes many other medicines, which can lead to important drug interactions [12].

How does rifampicin interact with sildenafil?

Rifampicin is what is known as a CYP3A4 inducer. This means it speeds up the activity of an enzyme in your liver (CYP3A4) that breaks down sildenafil and many other medicines [3]. When rifampicin increases the activity of this enzyme, sildenafil is broken down and removed from your body much faster than normal. As a result, the level of sildenafil in your bloodstream may be too low to produce the desired effect, and you may find that sildenafil does not work well—or at all—for your erectile dysfunction.

This interaction does not make sildenafil dangerous; it simply makes it less effective. The problem is that even if you take a higher dose of sildenafil, rifampicin may still reduce its effectiveness significantly. This is different from some other drug interactions where the concern is that medicine levels become too high; here, the concern is that sildenafil levels become too low to help [3].

Why CYP3A4 inducers matter

CYP3A4 is one of the main enzymes responsible for breaking down medicines in the liver. When a medicine like rifampicin induces (speeds up) this enzyme, it affects not only sildenafil but also many other medicines, including some contraceptives, blood thinners, and heart medicines. That is why your doctor or pharmacist will always review all your current medicines when you start rifampicin, and why it is so important to tell your prescriber about rifampicin when requesting ED treatment [12].

What does your prescriber check when you take sildenafil and rifampicin?

When you request sildenafil through an online consultation at Cured Pharmacy, you will be asked to list all your current medicines, including antibiotics like rifampicin. A UK-registered prescriber will review your answers carefully. If you are taking rifampicin, the prescriber will consider several factors: how long you have been on rifampicin, how long your course will last, whether your ED treatment is urgent, and whether there are alternative options that might work better during your antibiotic treatment.

The prescriber may decide that sildenafil is unlikely to be effective while you are on rifampicin and may suggest waiting until your rifampicin course is finished, if that is practical. Alternatively, they may discuss trying a different PDE5 inhibitor, though all PDE5 inhibitors (including tadalafil, vardenafil and avanafil) are affected to some degree by rifampicin [3][4][5][6]. In some cases, the prescriber may suggest a higher dose of sildenafil or a different type of ED treatment altogether, such as a topical gel or alprostadil, which are not affected by rifampicin in the same way.

Declaring all your medicines

It is essential to declare rifampicin—and every other medicine you take, including over-the-counter products and herbal remedies—during your consultation. Even if you think a medicine is unrelated to ED, it may interact with sildenafil or affect your suitability for treatment. Your prescriber cannot make a safe decision without complete and accurate information [2].

Are there safer alternatives to sildenafil when taking rifampicin?

All PDE5 inhibitors—sildenafil, tadalafil (Cialis), vardenafil (Levitra) and avanafil (Spedra)—are broken down by the same liver enzyme (CYP3A4), so rifampicin reduces the effectiveness of all of them [3][4][5][6]. This means switching to another tablet for ED is unlikely to solve the problem completely. However, some prescribers may consider tadalafil because it has a longer duration of action (up to 36 hours), which may give a slightly better chance of some effect even with reduced levels, though this is not guaranteed.

Non-tablet options may be more reliable during rifampicin treatment. Eroxon is a topical gel that works locally on the penis and does not rely on absorption into the bloodstream, so it is not affected by rifampicin. It is available without prescription. Vitaros (alprostadil cream) and Caverject (alprostadil injection) are prescription treatments that work differently from PDE5 inhibitors and are also not affected by rifampicin, though they require training and are usually reserved for cases where tablets do not work [7]. Your prescriber or GP can discuss these options with you.

Practical advice if you need both sildenafil and rifampicin

If you are starting rifampicin and are already taking sildenafil, tell your doctor or pharmacist straight away. You may find that sildenafil stops working or becomes much less effective within a few days of starting rifampicin, because the enzyme induction happens quite quickly. Do not simply increase your sildenafil dose on your own—this is unlikely to help much and may increase the risk of side effects without giving you the benefit you need.

If your rifampicin course is short (for example, a few weeks for certain infections), it may be practical to pause ED treatment temporarily and restart sildenafil once the antibiotic course is finished. Rifampicin's effect on the liver enzyme can persist for a couple of weeks after you stop taking it, so your prescriber may advise waiting a short time before restarting sildenafil to allow your body to return to normal [12].

If you are on long-term rifampicin (for example, a six-month TB treatment), discuss with your GP or sexual health specialist whether a non-tablet ED treatment might be more suitable during this time. It is also worth addressing any underlying causes of ED—such as managing diabetes, reducing alcohol, stopping smoking, and staying active—as these lifestyle changes can improve erectile function regardless of which medicines you take [1][2].

Do not stop rifampicin without medical advice

Rifampicin is prescribed for serious infections, and it is vital that you complete the full course exactly as directed by your doctor. Stopping rifampicin early or missing doses can lead to treatment failure and antibiotic resistance, which can be dangerous. Never stop or change your rifampicin treatment to make sildenafil work better—always speak to your doctor first [12].

Other medicines that affect sildenafil and rifampicin

Rifampicin interacts with many medicines besides sildenafil, including some contraceptives, warfarin, and medicines for HIV, so your doctor will review all your medicines when you start it. Similarly, sildenafil has important interactions of its own. You must never take sildenafil with nitrates (such as GTN spray or isosorbide mononitrate for angina), nicorandil, riociguat, or recreational drugs called poppers (amyl or alkyl nitrites), because the combination can cause a dangerous drop in blood pressure [3].

If you take medicines called alpha-blockers (such as tamsulosin or doxazosin, often prescribed for prostate problems or high blood pressure), you can usually still take sildenafil, but you must be stable on the alpha-blocker first and start on the lowest dose of sildenafil. Your prescriber will check this during your consultation [3]. Other blood-pressure medicines can add to the blood-pressure-lowering effect of sildenafil, which may cause dizziness, but this is usually manageable and does not mean you cannot take sildenafil—it just needs to be reviewed.

Some other antibiotics and antifungal medicines (such as clarithromycin, erythromycin, ketoconazole and itraconazole) have the opposite effect to rifampicin: they slow down the breakdown of sildenafil, which can increase sildenafil levels and the risk of side effects. If you are prescribed one of these medicines, your prescriber may reduce your sildenafil dose temporarily [3]. Always check with your prescriber or pharmacist before starting any new medicine while taking sildenafil.

Scientific References

1. NHS. (n.d.). Erectile dysfunction (impotence). NHS website. https://www.nhs.uk/conditions/erection-problems-erectile-dysfunction/ [accessed 16 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 16 October 2026]
3. Joint Formulary Committee. (n.d.). Sildenafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/sildenafil/ [accessed 16 October 2026]
4. Joint Formulary Committee. (n.d.). Tadalafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/tadalafil/ [accessed 16 October 2026]
5. Joint Formulary Committee. (n.d.). Vardenafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/vardenafil/ [accessed 16 October 2026]
6. Joint Formulary Committee. (n.d.). Avanafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/avanafil/ [accessed 16 October 2026]
7. Joint Formulary Committee. (n.d.). Alprostadil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/alprostadil/ [accessed 16 October 2026]
8. Electronic Medicines Compendium. (n.d.). Summaries of Product Characteristics and Patient Information Leaflets. https://www.medicines.org.uk/emc/ [accessed 16 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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