article icon
article

Amoxicillin Interactions: What You Need to Know

Dr Karen Martin
Reviewed by Dr Karen MartinReviewed on 12.03.2025 | 4 minutes read
EmailFacebookPinterestTwitter

Amoxicillin is a widely used antibiotic that treats bacterial infections ranging from sinusitis to urinary tract infections. While it’s generally well-tolerated and effective, interactions with other medications, supplements, and even certain foods can sometimes lead to unexpected effects. These interactions may reduce the effectiveness of the antibiotic, increase side effects, or influence how other medicines work in your body.

Interactions occur when two or more medicines affect each other’s function. Amoxicillin has the potential to interact with various drugs, making it essential to inform your doctor and pharmacist about all the medications and supplements you use. This ensures they can assess whether amoxicillin is safe and appropriate for you.

Below, we’ll outline the most important amoxicillin interactions and explain how they can be managed to keep your treatment both safe and effective.

Doctor’s advice

What medicines does amoxicillin interact with?

Amoxicillin can reduce the elimination of methotrexate from your body, which can increase your risk of developing side effects. If you are taking these medications together, your doctor may want to increase your normal methotrexate monitoring (testing your blood, liver, and kidneys). You should also report any side effects to your doctor, such as a sore throat.

Certain blood thinners (anticoagulants), including warfarin, may interact with amoxicillin. This may increase your risk of bleeding; therefore, it is important to let whoever monitors your blood thinner testing (INR) know you are taking it.

Allopurinol, a medication to treat gout, can interact with amoxicillin, causing an increased risk of developing a skin rash. You should speak to your doctor if this occurs.

Amoxicillin can reduce the effectiveness of the oral typhoid vaccine. It, therefore, should not be taken within three days (before or after) of the vaccine. Let your doctor know if you are taking amoxicillin and are due to have this vaccine.

If you suffer from vomiting and diarrhea as a side effect of amoxicillin, be sure that you discuss it with your doctor. If you are unable to take your other regular medication, some issues may arise. One example would be the contraceptive pill, which can put you at risk of pregnancy if you are unable to take it or keep it down. There are many other important medications that can’t be missed, and it is something to think carefully about or discuss with your doctor.

Are there any over-the-counter medications I need to avoid?

There are several medications to avoid, but here are some of the main ones.

Medications to be cautious about

  1. Antacids:

    • Antacids containing aluminum or magnesium hydroxide (e.g., Gaviscon, Rennie) may reduce the absorption of amoxicillin, potentially lowering its effectiveness.
  2. NSAIDs (e.g., ibuprofen):

    • It is generally safe, but excessive use could increase the risk of kidney strain, especially if you are already dehydrated or have kidney concerns. Consult a healthcare provider if unsure.
  3. Laxatives:

    • Some laxatives, especially those with magnesium (e.g., milk of magnesia), may also reduce amoxicillin absorption.

Amoxicillin is unlikely to interact with any other over-the-counter medicines, however you should speak with your pharmacist first before deciding to start taking any new over-the-counter medicines alongside amoxicillin.

Does this include herbal medicines?

Some herbal medicines can interact with amoxicillin, such as acacia, chewing catha, and bromelain. There are limited studies on the safety of taking herbal medicines alongside prescribed medications, so generally, it is best to avoid doing so.

Frequently asked questions around amoxicillin

Can I take amoxicillin with painkillers?

Yes, amoxicillin is generally safe to take with common painkillers like acetaminophen and ibuprofen. However, you should avoid combining it with aspirin or other nonsteroidal anti-inflammatory drugs (NSAIDs) without medical advice if you have a sensitive stomach, as this combination might increase the risk of stomach irritation.

Does amoxicillin interact with alcohol?

There’s no direct interaction between amoxicillin and alcohol, meaning alcohol won’t reduce the effectiveness of the antibiotic. However, drinking alcohol can worsen potential side effects like nausea, dizziness, and stomach upset. It’s best to limit alcohol intake while recovering from an infection to avoid additional strain on your body.

Can I take amoxicillin with oral contraceptives?

Amoxicillin may reduce the effectiveness of some oral contraceptives under rare circumstances by affecting gut bacteria that help with hormone absorption. Although the risk is low, using a backup method of contraception, such as condoms, is recommended during and for seven days after finishing the antibiotic course.

What happens if I take amoxicillin with blood thinners?

Amoxicillin may increase the effects of blood-thinning medications like warfarin, potentially raising the risk of bleeding. If you are on blood thinners, your doctor may monitor your INR (a measure of blood clotting) more closely during treatment.

Does amoxicillin affect probiotics or gut health?

Amoxicillin can disrupt gut bacteria, potentially leading to side effects like diarrhea. Probiotics may help restore healthy gut flora, but they should be taken a few hours apart from amoxicillin to ensure the antibiotic doesn’t reduce their effectiveness.

Can I take amoxicillin with antihistamines?

Yes, amoxicillin can generally be taken with antihistamines like loratadine or cetirizine. However, always check with a pharmacist if you’re using combination medications that contain other active ingredients.

The AI in healthwords.ai refers to conversational search, while the only AI tools used for articles are grammar and language improvements -  medical content remains rigorously authored by healthcare professionals.

Was this helpful?

This article has been written by UK-based doctors and pharmacists, so some advice may not apply to US users and some suggested treatments may not be available. For more information, please see our T&Cs.
Dr Karen Martin
Reviewed by Dr Karen Martin
Reviewed on 12.03.2025
EmailFacebookPinterestTwitter