Can You Take Tadalafil and Amoxicillin Together?
Learn about the interaction between these medicines and how our UK prescribers ensure your safety.
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Tadalafil and Amoxicillin: Understanding the Interaction
Published: 18 October 2026
Many men wonder whether tadalafil and amoxicillin can be taken together safely. The good news is that no major interaction is commonly reported between tadalafil (Cialis) and amoxicillin, a widely used penicillin antibiotic. However, your prescriber will still review all your current medicines during your consultation to ensure the combination is appropriate for you.
At a glance
What Is Tadalafil and How Does It Work?
Tadalafil is a prescription medicine licensed in the UK for erectile dysfunction (ED). It belongs to a group of medicines called PDE5 inhibitors, which work by relaxing 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.
Tadalafil is available in two forms: on-demand tablets (10mg or 20mg taken at least 30 minutes before sex, with effects lasting up to 36 hours) and daily tablets (2.5mg or 5mg taken once a day) [4]. Unlike some other ED treatments, tadalafil's long duration of action means you don't need to time it as precisely before sexual activity. However, sexual stimulation is still required for the medicine to work.
Common side effects of tadalafil include headache, indigestion, back pain, muscle aches, flushing, and nasal congestion [4]. These are usually mild and temporary. Tadalafil is not suitable for everyone, particularly men taking nitrates, nicorandil, riociguat, or those for whom sexual activity is inadvisable due to heart problems.
What Is Amoxicillin and When Is It Prescribed?
Amoxicillin is a penicillin-type antibiotic commonly prescribed in the UK to treat bacterial infections such as chest infections, dental abscesses, urinary tract infections, and ear infections. It works by killing bacteria or stopping them from multiplying, allowing your immune system to clear the infection.
Amoxicillin is usually taken two or three times a day, depending on the dose and type of infection being treated. It's important to complete the full course of antibiotics even if you feel better, to ensure the infection is fully cleared and to reduce the risk of antibiotic resistance.
Common side effects of amoxicillin include feeling sick, diarrhoea, and skin rash. Some people are allergic to penicillin antibiotics; if you develop a rash, itching, swelling, or difficulty breathing after taking amoxicillin, seek medical help immediately. Amoxicillin does not directly affect erectile function or sexual performance.
Does Amoxicillin Cause Erectile Dysfunction?
Amoxicillin itself is not known to cause erectile dysfunction. However, feeling unwell with an infection can temporarily reduce your interest in sex or affect your ability to get an erection. This is a normal response to illness and usually resolves once you've recovered and completed your antibiotic course.
Can You Take Tadalafil and Amoxicillin Together?
There is no major drug interaction commonly reported between tadalafil and amoxicillin. Amoxicillin does not significantly affect how tadalafil is broken down in the body, and tadalafil does not interfere with how amoxicillin works to treat bacterial infections. This means the two medicines can generally be taken together when both are needed.
However, it's essential to declare all medicines you're taking—including antibiotics—during your online consultation for ED treatment. Your prescriber needs a complete picture of your current health and medications to ensure tadalafil is safe and appropriate for you. Even when no major interaction exists, individual circumstances can vary.
Some antibiotics, particularly certain strong antifungals like ketoconazole and itraconazole, or macrolide antibiotics like clarithromycin, can interact with tadalafil by raising its levels in the blood [4]. Amoxicillin does not have this effect, but your prescriber will check every medicine you're taking to identify any potential issues and adjust your treatment if needed.
What you need to know
- No major interaction is commonly reported between tadalafil and amoxicillin
- Always declare all medicines including antibiotics during your ED consultation
- Some other antibiotics may require tadalafil dose adjustment
- Feeling unwell with infection may temporarily affect erectile function
- Complete your antibiotic course and take tadalafil as directed
How Tadalafil and Amoxicillin Are Processed in the Body
Understanding how medicines are processed helps explain why tadalafil and amoxicillin don't usually interact. Tadalafil is broken down primarily by an enzyme system in the liver called CYP3A4 [4]. Medicines that strongly inhibit or activate this enzyme can affect tadalafil levels, potentially increasing side effects or reducing effectiveness.
Amoxicillin, by contrast, is not significantly metabolised by liver enzymes. It is mainly eliminated unchanged through the kidneys. Because amoxicillin doesn't interfere with the CYP3A4 enzyme system, it doesn't alter how quickly or slowly tadalafil is broken down in your body.
This difference in metabolic pathways is why amoxicillin and tadalafil can usually be taken together without dose adjustment. However, if you have kidney or liver problems, your prescriber may need to adjust the dose of either medicine. Always be honest about any health conditions during your consultation.
What About Other Antibiotics?
While amoxicillin is safe with tadalafil, some other antibiotics require caution. Clarithromycin and erythromycin (macrolide antibiotics) are potent CYP3A4 inhibitors and can raise tadalafil levels, requiring dose adjustment [4]. Rifampicin, used for tuberculosis, is a CYP3A4 inducer and may make tadalafil less effective. Your prescriber will check the specific antibiotic you're taking and adjust your ED treatment accordingly.
What Your Prescriber Checks Before Approving Tadalafil
When you request tadalafil through Cured Pharmacy, a UK-registered prescriber reviews your online consultation before any medicine is supplied. They check your current medications (including antibiotics like amoxicillin), medical history, blood pressure, and whether you have any conditions that make tadalafil unsuitable [2].
The prescriber will specifically look for medicines that must never be taken with tadalafil: nitrates (GTN spray, isosorbide mononitrate or dinitrate), nicorandil, riociguat, and amyl or alkyl nitrites (poppers). These combinations can cause a dangerous drop in blood pressure [4]. They'll also check for medicines that may require a lower starting dose of tadalafil, such as alpha-blockers for prostate problems.
If you're taking amoxicillin for an infection, the prescriber will note this but it won't usually prevent you from using tadalafil. However, if you're feeling very unwell with the infection, they may advise waiting until you've recovered before starting ED treatment. Sexual activity itself requires a degree of physical exertion, which may not be advisable when you're acutely ill.
When to get urgent help
- Erection lasting more than 4 hours (priapism) – go to A&E immediately
- Sudden loss of vision or hearing – stop tadalafil and seek urgent medical help
- Chest pain during sex – stop activity and call 999; do not take nitrates if you've used tadalafil recently
- Severe allergic reaction to amoxicillin (rash, swelling, difficulty breathing) – call 999
- Severe dizziness or fainting – seek same-day medical advice
Call 999 or go to A&E in an emergency, or contact NHS 111 for urgent advice.
Practical Advice for Taking Tadalafil and Amoxicillin
If you've been prescribed both tadalafil and amoxicillin, take each medicine exactly as directed. Amoxicillin should be taken at evenly spaced intervals (e.g. every 8 or 12 hours) to maintain steady levels and fight the infection effectively. Complete the full antibiotic course even if you feel better.
For on-demand tadalafil (10mg or 20mg), take it at least 30 minutes before you plan to have sex, with or without food [4]. The effects can last up to 36 hours, so you don't need to take it every day. If you're on daily tadalafil (2.5mg or 5mg), take it at the same time each day. You can take tadalafil and amoxicillin at the same time of day or separately—there's no need to space them out.
Avoid heavy alcohol while taking either medicine. Alcohol can worsen ED, increase the risk of side effects from tadalafil (such as dizziness or low blood pressure), and may reduce the effectiveness of your antibiotic treatment. If you experience side effects from either medicine, or if your erection lasts more than four hours, seek medical advice promptly [1].
When to Seek Medical Advice
Contact your GP or prescriber if you develop new symptoms while taking tadalafil and amoxicillin together, such as severe dizziness, chest pain, or an allergic reaction (rash, swelling, difficulty breathing). If your infection isn't improving after a few days of amoxicillin, or if you develop side effects from tadalafil that concern you, don't hesitate to seek advice. Never stop a prescribed antibiotic early without consulting a healthcare professional.
Always Declare Your Antibiotics
Even though amoxicillin doesn't interact with tadalafil, always list every medicine you're taking during your consultation. This helps your prescriber spot any potential issues and ensure your treatment is safe.
Scientific References
- NHS. (n.d.). Erectile dysfunction (impotence). NHS website. https://www.nhs.uk/conditions/erection-problems-erectile-dysfunction/ [accessed 18 October 2026]
- National Institute for Health and Care Excellence. (n.d.). Erectile dysfunction. Clinical Knowledge Summaries. https://cks.nice.org.uk/topics/erectile-dysfunction/ [accessed 18 October 2026]
- Joint Formulary Committee. (n.d.). Tadalafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/tadalafil/ [accessed 18 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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Common Questions
Is it safe to take tadalafil and amoxicillin at the same time?
Yes, no major interaction is commonly reported between tadalafil and amoxicillin, so they can usually be taken together. Always declare all medicines during your consultation.
Will amoxicillin make tadalafil less effective?
No, amoxicillin does not affect how tadalafil works. However, feeling unwell with an infection may temporarily affect your interest in sex or erectile function.
Do I need to wait until I finish my antibiotics before taking tadalafil?
Not necessarily. If you're well enough for sexual activity and your prescriber approves, you can take tadalafil while on amoxicillin. However, if you're acutely unwell, it may be better to wait until you've recovered.
Can antibiotics cause erectile dysfunction?
Amoxicillin itself does not cause ED. However, the infection you're treating or feeling generally unwell can temporarily reduce sexual function, which usually improves once you've recovered.
What antibiotics should I avoid with tadalafil?
Clarithromycin and erythromycin can raise tadalafil levels and may require dose adjustment. Rifampicin may reduce tadalafil's effectiveness. Your prescriber will check any antibiotic you're taking.
Should I tell my prescriber I'm taking amoxicillin?
Yes, always declare all current medicines, including antibiotics, during your online consultation. This helps your prescriber ensure tadalafil is safe and appropriate for you.
Can I drink alcohol while taking tadalafil and amoxicillin?
Heavy alcohol should be avoided as it can worsen ED, increase tadalafil side effects like dizziness, and may reduce the effectiveness of your antibiotic treatment.
What should I do if I get side effects from taking both medicines?
Contact your GP or prescriber if you develop concerning symptoms such as severe dizziness, chest pain, allergic reactions, or side effects that worry you. Never stop antibiotics early without medical advice.
Medically reviewed by
Tarun Kumar, Superintendent Pharmacist (GPhC 2233073)