Tadalafil and Cefixime: Can You Take Them Together?

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Tadalafil and Cefixime: Understanding the Interaction

Published: 19 October 2026

Many men wonder whether tadalafil and cefixime can be taken together safely. The good news is that cefixime, a commonly prescribed antibiotic, is not known to have a major interaction with tadalafil (the active ingredient in Cialis) or other erectile dysfunction medicines. However, every medicine you take—whether prescribed, over-the-counter, or herbal—must be declared during your consultation so that your prescriber can review your full medication list and ensure the combination is appropriate for you [2][3][4].

What Is Tadalafil and Cefixime?

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 [1][4]. Tadalafil is available on-demand (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) [4]. It requires sexual stimulation to work and does not cause an automatic erection.

Cefixime is a cephalosporin antibiotic used to treat bacterial infections, including respiratory tract infections, urinary tract infections, and some sexually transmitted infections such as gonorrhoea [12]. It works by killing bacteria and is typically prescribed as a short course (often a single dose or a few days). Cefixime does not affect sexual function directly, but treating an underlying infection may improve your overall health and wellbeing.

Is There an Interaction Between Tadalafil and Cefixime?

No major interaction between tadalafil and cefixime is commonly reported in clinical practice or drug interaction databases [3][4][12]. Cefixime does not significantly affect the liver enzymes (CYP3A4) that break down tadalafil, so it is unlikely to raise or lower tadalafil levels in your bloodstream. This means that, in most cases, the two medicines can be taken together without needing to adjust the dose of either.

However, it is essential to tell your prescriber or pharmacist about every medicine you are taking, including antibiotics. During your online consultation at Cured Pharmacy, you will be asked to list all current medications so that the UK-registered prescriber can check for any potential interactions and confirm that tadalafil is safe for you. Even when no major interaction is expected, individual health conditions and other medicines you take can influence safety.

Why Declaring All Medicines Matters

Some antibiotics—particularly potent CYP3A4 inhibitors such as clarithromycin and erythromycin—can raise tadalafil levels and increase the risk of side effects [4]. While cefixime does not have this effect, your prescriber needs to know your full medication history to rule out other interactions. For example, if you are also taking blood pressure medicines, alpha-blockers, or any other drugs, these may interact with tadalafil and require dose adjustments or additional monitoring [2][3][4].

What Your Prescriber Checks Before Approving Tadalafil and Cefixime

When you request tadalafil through Cured Pharmacy's online consultation, a UK-registered prescriber will review your medical history, current medicines (including cefixime), and any underlying health conditions [2]. They will check that you do not have contraindications to tadalafil, such as recent heart attack or stroke, unstable angina, severe heart failure, very low blood pressure, or use of nitrates, nicorandil, riociguat, or recreational drugs known as 'poppers' [3][4]. These combinations can cause a dangerous drop in blood pressure and must never be used together.

The prescriber will also assess whether you are taking alpha-blockers (such as tamsulosin or doxazosin) for prostate symptoms or high blood pressure. If you are, you should be stable on the alpha-blocker before starting tadalafil, and the lowest effective dose of tadalafil will be recommended to minimise the risk of dizziness or fainting [4]. If you are on any potent CYP3A4 inhibitors (such as ritonavil, ketoconazole, or itraconazole), your tadalafil dose may need to be reduced [4]. Cefixime does not fall into this category, so it does not require dose adjustment.

Practical Advice for Taking Tadalafil and Cefixime Together

If your prescriber has approved tadalafil and you are also taking cefixime, you can generally take both medicines as directed without special timing requirements. Tadalafil can be taken with or without food, though a very large or high-fat meal may delay its onset slightly [4]. Cefixime is usually taken with water and can be taken with or without food, depending on the formulation and your prescriber's instructions [12].

Continue your antibiotic course exactly as prescribed, even if you start to feel better before it is finished. Stopping antibiotics early can lead to the infection returning or antibiotic resistance. If you experience any unusual symptoms while taking both medicines—such as severe dizziness, chest pain, sudden vision or hearing loss, or an erection lasting more than four hours—seek urgent medical help [1][4]. These are rare but serious side effects of tadalafil that require immediate attention.

Lifestyle Considerations

Avoid drinking excessive alcohol while taking tadalafil, as heavy drinking can worsen erectile dysfunction and add to the blood-pressure-lowering effect of the medicine, increasing the risk of dizziness [1][4]. Grapefruit juice can raise tadalafil levels and should be avoided or limited [4]. If you are unwell with an infection, it is normal for sexual desire and performance to be affected temporarily; treating the infection with cefixime should help you feel better overall.

Other Antibiotics and Tadalafil: What You Need to Know

While cefixime does not interact significantly with tadalafil, some other antibiotics do require caution. Macrolide antibiotics such as clarithromycin and erythromycin are potent CYP3A4 inhibitors and can raise tadalafil levels in the blood, increasing the risk of side effects such as headache, flushing, indigestion, or low blood pressure [4]. If you are prescribed one of these antibiotics, your prescriber may recommend a lower dose of tadalafil or advise you to pause tadalafil temporarily while you complete the antibiotic course.

Azithromycin, another commonly used macrolide, is a weaker CYP3A4 inhibitor and is generally considered safer to use with tadalafil, though your prescriber will still review the combination [4]. Penicillins (such as amoxicillin) and most other cephalosporins (the same family as cefixime) do not interact with tadalafil. Always inform your prescriber or pharmacist of any new antibiotic prescription so they can check for interactions with your ED treatment [2][3][4].

When to Seek Medical Advice About Tadalafil and Cefixime

If you develop new symptoms or side effects while taking tadalafil and cefixime together, contact your GP or pharmacist for advice. Common side effects of tadalafil include headache, indigestion, back pain, muscle aches, flushing, and nasal congestion; these are usually mild and temporary [4]. Cefixime can cause diarrhoea, nausea, or abdominal discomfort [12]. If you experience severe or persistent diarrhoea, especially with blood or mucus, stop cefixime and seek medical advice, as this may indicate a serious bowel infection (Clostridioides difficile) [12].

Seek urgent medical help (call 999 or go to A&E) if you experience chest pain during sex, an erection lasting more than four hours (priapism), sudden loss of vision or hearing, or signs of a severe allergic reaction such as swelling of the face, lips, or throat, or difficulty breathing [1][4]. These are rare but serious events. If you have any concerns about whether tadalafil is right for you, or if your erectile dysfunction persists despite treatment, see your GP. ED can be an early warning sign of cardiovascular disease or diabetes, and it is important to address any underlying health issues [1][2].

Ongoing Support from Cured Pharmacy

At Cured Pharmacy, our UK-registered pharmacists and prescribers are here to support you. If you have questions about taking tadalafil with cefixime or any other medicine, you can contact our team for advice. Every prescription is reviewed individually to ensure it is safe and appropriate for you. We offer a range of ED treatments, including generic and branded options, all supplied following a confidential online consultation.

Scientific References

1. NHS. (n.d.). Erectile dysfunction (impotence). NHS website. https://www.nhs.uk/conditions/erection-problems-erectile-dysfunction/ [accessed 19 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 19 October 2026]
3. Joint Formulary Committee. (n.d.). Sildenafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/sildenafil/ [accessed 19 October 2026]
4. Joint Formulary Committee. (n.d.). Tadalafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/tadalafil/ [accessed 19 October 2026]
5. Electronic Medicines Compendium. (n.d.). Summaries of Product Characteristics and Patient Information Leaflets. https://www.medicines.org.uk/emc/ [accessed 19 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.