Azithromycin Drug Interactions: Medicines, Foods, and Supplements to Avoid
Among the macrolide antibiotics, azithromycin has a reputation as the “quiet” one. Its cousins clarithromycin and erythromycin strongly block a liver enzyme called CYP3A4, which tangles them up with statins, calcium-channel blockers, certain anti-epilepsy drugs and dozens more. Azithromycin barely touches that enzyme. That is good news – but “fewer interactions” is not “no interactions.” The ones azithromycin does have are concentrated in a few high-stakes areas, especially heart rhythm.
Rather than an alphabetical list, this guide is organised by how each interaction happens, then sorted into a red-amber-green tier system so you can see quickly which combinations need action. It ends with a “bring your bag” medicine audit you can use with your pharmacist.
Key points: The most important azithromycin interactions involve (1) other medicines that prolong the QT interval, such as some antiarrhythmics, antipsychotics, antidepressants, methadone, ondansetron and hydroxychloroquine; (2) drugs moved around the body by the P-glycoprotein pump, such as digoxin and colchicine; (3) warfarin, where bleeding risk may rise; (4) nelfinavir; and (5) aluminium- or magnesium-containing antacids, which should not be taken at the same time. Food, dairy and grapefruit are not meaningful problems. Live oral vaccines for typhoid and cholera can be weakened by antibiotics.
Why azithromycin interacts less than other macrolides
Erythromycin and clarithromycin bind tightly to CYP3A4, the enzyme that breaks down roughly half of commonly used medicines. When it is blocked, levels of other drugs rise. Azithromycin’s 15-membered ring structure gives it a much weaker hold on CYP3A4. The US Zithromax label includes studies showing little or no meaningful effect on drugs such as carbamazepine, cetirizine, theophylline, midazolam and triazolam at standard doses.
Most of azithromycin is eliminated unchanged in bile, not through extensive liver metabolism. So the classic “enzyme interaction” story mostly does not apply. Instead, its interactions come from four other mechanisms.
Mechanism 1: QT stacking
The QT interval on an electrocardiogram reflects how long the heart’s lower chambers take to recharge between beats. Many medicines lengthen it a little. On its own, a small lengthening usually causes no harm. But effects can add up, and a long enough QT can trigger torsades de pointes, a dangerous rhythm. In 2013 the FDA strengthened azithromycin’s warnings about QT prolongation, noting higher risk in people already taking QT-prolonging drugs.
Common QT-prolonging medicines to flag
| Category | Examples | Why it matters with azithromycin |
|---|---|---|
| Antiarrhythmics | Amiodarone, sotalol, dronedarone, dofetilide, quinidine, procainamide | Strong QT effects; combination generally avoided |
| Antipsychotics | Haloperidol, quetiapine, ziprasidone, chlorpromazine, pimozide | Additive QT effect; specialist review |
| Antidepressants | Citalopram, escitalopram, amitriptyline and other tricyclics | Dose-related QT effect; caution |
| Opioids | Methadone | Significant QT risk; see methadone and oxycodone and methadone and tramadol |
| Anti-nausea drugs | Ondansetron, domperidone | Often given together during gastroenteritis; caution with high doses or IV use |
| Antimalarials | Hydroxychloroquine, chloroquine, quinine, halofantrine | Additive QT; this combination drew attention in 2020 |
| Other antibiotics and antifungals | Levofloxacin, moxifloxacin, clarithromycin, erythromycin, fluconazole | Added QT risk when combined |
| Others | Hydroxyzine, some cancer drugs, cisapride | Check individually; CredibleMeds keeps an up-to-date list |
Risk is highest when QT drugs combine with other factors: older age, female sex, heart disease, slow heart rate, and low potassium or magnesium (often from vomiting, diarrhoea or diuretics). Your prescriber may choose a different antibiotic, check an ECG, or correct electrolytes first.
Mechanism 2: the P-glycoprotein pump
P-glycoprotein (P-gp) is a cellular pump that pushes some drugs out of gut cells and into urine and bile. Azithromycin can inhibit this pump, which can raise levels of medicines that depend on it.
- Digoxin: higher digoxin levels have been reported. Signs of toxicity include nausea, vomiting, visual changes (yellow-green tinge), confusion and slow or irregular heartbeat. Your doctor may monitor levels.
- Colchicine: raised colchicine exposure can cause severe diarrhoea, muscle pain and, rarely, life-threatening toxicity. People with kidney or liver problems are at greatest risk. Dose adjustment or monitoring may be needed.
- Some immunosuppressants: cyclosporine levels may rise with macrolides; transplant teams usually monitor blood levels when an antibiotic is added. Tacrolimus is mainly a CYP3A4 issue with clarithromycin, but transplant patients should still tell their team about any new antibiotic.
Mechanism 3: absorption in the gut
Aluminium- and magnesium-containing antacids (for example, some formulations of Maalox, Mylanta, Gelusil and Digene) lower the peak level of azithromycin in the blood. The Zithromax patient information tells people not to take these antacids at the same time as azithromycin. A practical approach many pharmacists use is to separate them by at least two hours.
Food is different. Standard tablets and the usual suspension can be taken with or without food. (An extended-release suspension sold as Zmax in some markets had different rules; follow the label on whatever product you were given.)
Mechanism 4: changes in blood thinning and gut flora
Warfarin: post-marketing reports describe increased anticoagulant effect when azithromycin is given with warfarin. The mechanism is not fully understood; infection, reduced eating and changes in gut bacteria that make vitamin K may all contribute. If you take warfarin, your INR may need checking during or soon after the course. Watch for unusual bruising, nosebleeds, bleeding gums, blood in urine or black stools.
Live oral vaccines: antibiotics can kill the live bacteria in oral typhoid (Ty21a) and oral cholera vaccines, making them less effective. The CDC advises spacing these vaccines from antibiotics. If you are preparing for travel, tell your travel clinic about any recent or planned antibiotic course.
The red-amber-green interaction tiers
Red – usually avoid, or only with specialist oversight
| Medicine | Concern | Typical action |
|---|---|---|
| Class Ia and III antiarrhythmics (amiodarone, sotalol, dofetilide, quinidine) | Additive QT prolongation | Choose another antibiotic or monitor closely |
| Pimozide | Serious QT risk | Avoid combination |
| Other macrolides or QT-heavy antibiotics given together | Stacked QT effect | Rarely needed; prescriber decision |
| Live oral typhoid or cholera vaccine | Vaccine inactivated | Reschedule vaccine as advised |
Amber – may be used with adjustment, timing or monitoring
| Medicine | Concern | Typical action |
|---|---|---|
| Warfarin | Increased bleeding risk | Check INR; watch for bleeding |
| Digoxin | Higher digoxin levels | Monitor symptoms and levels |
| Colchicine | Toxicity risk | Dose review, especially with kidney/liver disease |
| Nelfinavir (HIV) | Raises azithromycin levels | Monitor for liver changes and hearing problems |
| Cyclosporine | Possible level rise | Blood level monitoring |
| Citalopram, escitalopram, tricyclic antidepressants | Additive QT effect | Review dose and other risk factors |
| Antipsychotics (e.g. haloperidol, quetiapine) | Additive QT effect | ECG may be considered |
| Methadone | Additive QT effect | Inform prescriber; ECG in higher-risk cases |
| Ondansetron, domperidone | Additive QT effect | Use lowest dose; avoid in known long QT |
| Hydroxychloroquine, chloroquine | Additive QT effect | Avoid unless clear benefit; monitor |
| Fluoroquinolones (levofloxacin, moxifloxacin) | Additive QT effect | Usually not combined; specific indications only |
| Ergot alkaloids (ergotamine) | Macrolides linked to ergot toxicity | Generally avoided as precaution |
| Phenytoin | Listed in patient information as one to tell your provider about | Seizure control and levels may be monitored |
| Diuretics (furosemide, hydrochlorothiazide) | Can lower potassium/magnesium, raising QT risk | Electrolyte check if other risks present |
Green – generally no clinically important interaction at usual doses
| Medicine or substance | Notes |
|---|---|
| Most statins (atorvastatin, rosuvastatin, simvastatin) | Unlike clarithromycin, azithromycin does not significantly block CYP3A4; rare case reports of muscle problems mean you should still report unexplained muscle pain |
| Hormonal contraceptives | No known reduction in effectiveness; vomiting or severe diarrhoea can still affect pill absorption |
| Paracetamol and ibuprofen | No direct interaction at normal doses |
| Cetirizine, loratadine | No meaningful interaction shown |
| Theophylline, carbamazepine, midazolam (single doses) | Label studies showed little effect |
| Fluconazole | No important pharmacokinetic interaction, though both affect QT |
| Proton pump inhibitors (omeprazole, pantoprazole) | Not known to affect azithromycin absorption meaningfully |
| Amoxicillin or ceftriaxone given together | Commonly co-prescribed for pneumonia; no chemical interaction |
“Green” does not mean “ignore.” Always tell your pharmacist everything you take, because your personal health conditions can change the picture.
Food and drink
| Item | Interaction? | Practical advice |
|---|---|---|
| Meals in general | No important effect for standard tablets and suspension | Take with food if it upsets your stomach |
| Milk and dairy | No meaningful binding problem (unlike tetracyclines and fluoroquinolones) | Fine to have |
| Grapefruit | Not a significant issue for azithromycin | No need to avoid for this drug |
| Caffeine | No direct interaction | Can add to palpitations if sensitive |
| Alcohol | No direct chemical interaction | Can worsen side effects; see alcohol and azithromycin |
| Energy drinks | No direct interaction | Avoid if you have heart rhythm concerns |
Supplements and herbal products
Supplements are less well studied, so caution is reasonable.
- Magnesium and aluminium-containing products (including some laxatives and indigestion remedies): separate from azithromycin doses.
- Calcium, iron and zinc: these do not bind azithromycin the way they bind tetracyclines or quinolones, but separating them by a couple of hours is a harmless precaution if you take high doses.
- Probiotics: no harmful interaction; some people take them a few hours apart from the antibiotic. Evidence is discussed in amoxicillin and diarrhea.
- Licorice root (glycyrrhizin): can lower potassium, which may raise QT risk.
- Stimulant weight-loss or “fat burner” supplements: can affect heart rhythm; best avoided during a course. See green tea for weight loss for caffeine content considerations.
- Herbal “liver tonics” and Ayurvedic preparations: composition varies widely; tell your doctor if you take any, especially if you have liver disease.
Situations that raise interaction stakes
Older adults on many medicines
People taking five or more medicines are more likely to be on at least one QT-prolonging drug and to have kidney or heart issues. A pharmacist medication review before starting azithromycin is worthwhile.
People with HIV
Azithromycin is used for MAC prevention and some STIs. Most current HIV regimens do not interact strongly, but nelfinavir does, and some protease inhibitors affect QT. Your HIV clinic should review the combination.
Heart patients
If you have a pacemaker, defibrillator, heart failure or a history of arrhythmia, ask whether azithromycin is the best choice and whether an ECG is needed.
Mental health medicines
Antipsychotics and some antidepressants add QT effects. Do not stop psychiatric medicines to “make room” for the antibiotic; ask your prescriber to weigh the options.
Long-term azithromycin users
People on months of azithromycin for lung disease should have each new medicine checked against it, because exposure is ongoing rather than a brief five days.
Your “bring your bag” medicine audit
Before starting azithromycin, gather everything you take and go through this checklist with your pharmacist or prescriber:
- Prescription medicines – including heart, mental health, epilepsy and HIV medicines.
- Over-the-counter products – antacids, anti-nausea tablets, cold remedies, sleep aids, laxatives.
- Supplements and herbal products – including Ayurvedic, traditional Chinese or homeopathic preparations.
- Recent or upcoming vaccines – especially oral typhoid or cholera vaccine for travel.
- Medical history flags – long QT, fainting episodes, slow heart rate, heart failure, liver disease, kidney disease, myasthenia gravis.
- Recent illness – vomiting or diarrhoea that may have lowered potassium or magnesium.
- Allergies – any previous reaction to erythromycin, clarithromycin or azithromycin.
Ask: “Do any of these interact with azithromycin, and do I need to change timing, check a blood test or have an ECG?”
Warning signs that an interaction may be happening
- Fainting, near-fainting, or a racing, pounding or irregular heartbeat – seek emergency care
- Unusual bleeding or bruising, black stools – contact your doctor urgently (especially on warfarin)
- Nausea, vomiting, visual colour changes or confusion on digoxin – seek urgent advice
- Severe diarrhoea, muscle pain or weakness on colchicine – stop colchicine and seek advice
- Yellowing of skin or eyes, dark urine – seek prompt medical care
- New ringing in the ears or hearing loss – contact your prescriber
How the three macrolides compare on interactions
People are often switched between macrolides, or told “it’s the same family,” so it helps to see why the interaction advice differs.
| Feature | Azithromycin | Clarithromycin | Erythromycin |
|---|---|---|---|
| CYP3A4 inhibition | Weak | Strong | Moderate to strong |
| Statin interactions (simvastatin, lovastatin) | Minimal | Major – often contraindicated | Major |
| Calcium-channel blockers | Minimal | Can cause low blood pressure | Can cause low blood pressure |
| Colchicine | Possible (P-gp) | Serious – potentially fatal toxicity | Serious |
| QT prolongation | Yes | Yes | Yes |
| Dosing frequency | Once daily | Twice daily | Up to four times daily |
This is why a pharmacist might be relaxed about azithromycin with your statin, but would stop you taking clarithromycin with the same tablet.
Condition-focused guide
Gout
If you take colchicine for gout flares or prevention, tell your prescriber before starting azithromycin. Early colchicine toxicity looks like severe diarrhoea, vomiting and muscle aches – easy to mistake for a stomach bug. Kidney or liver impairment increases the risk.
Heart failure and atrial fibrillation
Digoxin, amiodarone and diuretics are common in these conditions. Each creates a different interaction pathway: digoxin through P-gp, amiodarone through QT stacking, and diuretics through low potassium or magnesium. Your cardiologist or GP may prefer an alternative antibiotic.
Blood clots and stroke prevention
Warfarin users may need an INR check. People on direct oral anticoagulants (apixaban, rivaroxaban, dabigatran) generally have fewer reported interactions with azithromycin, but should still report unusual bleeding. Dabigatran is a P-gp substrate, so some clinicians apply extra caution.
Epilepsy
Azithromycin does not significantly change carbamazepine levels in label studies. Phenytoin appears in the patient information list of medicines to mention. Seizures have been very rarely reported with azithromycin, so anyone with epilepsy should report changes in seizure pattern.
Mental health conditions
Several antipsychotics and antidepressants prolong QT. The risk rises with higher doses and with combinations. Do not stop psychiatric medicines without advice; abrupt changes can cause relapse or withdrawal.
Opioid treatment programmes
People on methadone may already have a lengthened QT. Programme clinicians may request an ECG or choose a different antibiotic.
Transplant and autoimmune conditions
Cyclosporine and similar drugs have narrow safety margins. Always inform the transplant team before any new antibiotic. Note also the 2018 FDA warning about long-term azithromycin after donor stem cell transplant.
Worked example: a pharmacist’s review
Mr. Iyer, 72, is prescribed a Z-Pak for a chest infection. His medicine list includes atorvastatin, amlodipine, furosemide, digoxin and citalopram, plus an antacid he buys himself. A pharmacist might reason like this:
- Atorvastatin and amlodipine: little concern with azithromycin (would be a problem with clarithromycin).
- Furosemide: may lower potassium and magnesium; worth checking recent blood results because of QT risk.
- Digoxin: possible level rise; advise him and his family about warning signs and consider a level check.
- Citalopram: adds QT effect; with age, a diuretic and digoxin, an ECG or alternative antibiotic may be worth discussing with the prescriber.
- Antacid: if it contains aluminium or magnesium, separate it from the azithromycin dose.
The outcome might be azithromycin with monitoring, or a switch to a different antibiotic. The point is that the decision is made with the full list in view.
Timing guide for medicines that need spacing
| Product | Suggested approach |
|---|---|
| Aluminium/magnesium antacids | Not at the same time; many pharmacists suggest at least 2 hours apart |
| Magnesium-containing laxatives | Separate in the same way as antacids |
| Probiotics | Optional spacing of a few hours |
| High-dose calcium, iron or zinc | Optional 2-hour spacing as a precaution |
| Live oral typhoid or cholera vaccines | Ask your travel clinic; vaccines are typically separated from antibiotics by several days |
Interactions with over-the-counter products people forget to mention
When asked “what medicines do you take?”, most people list prescriptions and forget what they buy themselves. These everyday items are worth naming to your pharmacist:
| Product type | Examples | Relevance to azithromycin |
|---|---|---|
| Indigestion remedies | Antacid tablets and gels containing aluminium or magnesium | Separate doses |
| Anti-nausea tablets | Domperidone (outside the US), ondansetron | QT effects |
| Sleep aids | Diphenhydramine, doxylamine | Drowsiness; some antihistamines affect heart rhythm in high doses |
| Allergy tablets | Hydroxyzine (prescription in some places) | QT effects |
| Laxatives | Milk of magnesia | Separate doses |
| Diet and energy products | High-caffeine supplements, stimulant “fat burners” | Can affect heart rhythm |
| Traditional remedies | Licorice-based preparations | May lower potassium |
Pharmacy software flags many prescription interactions automatically, but it can only check what it knows about. A complete list – including these – is the best protection.
Frequently asked questions
Can I take azithromycin with ibuprofen or paracetamol?
Yes, there is no known direct interaction. Use standard doses and follow each product’s label.
Can I take azithromycin with my statin?
In most cases, yes. Azithromycin does not strongly affect statin levels the way clarithromycin and erythromycin do. Report any unexplained muscle pain or weakness.
How far apart should I take azithromycin and antacids?
Do not take aluminium- or magnesium-containing antacids at the same time. Many pharmacists suggest separating them by at least two hours. Ask about your specific product.
Does azithromycin interact with the birth control pill?
It is not known to reduce contraceptive effectiveness. If you vomit within a few hours of a pill or have severe diarrhoea, follow your pill’s missed-dose instructions.
Can I take azithromycin with ondansetron for nausea?
Often yes, especially at low oral doses in otherwise healthy people. Both affect QT, so people with heart risk factors or other QT drugs should check with their prescriber.
Can I take azithromycin with amoxicillin?
Yes, doctors sometimes prescribe both together for pneumonia. They do not interact chemically. See amoxicillin drug interactions for amoxicillin’s own list.
Is it safe with antidepressants?
Many antidepressants are fine, but citalopram, escitalopram and tricyclics add to QT risk. Do not stop them; ask your prescriber whether any monitoring is needed.
Can I take azithromycin with cough syrup?
Many cough syrups are fine, but check the ingredients. Some contain antihistamines or codeine that cause drowsiness, and a few cough and cold ingredients can affect heart rhythm in high doses. Ask your pharmacist.
Can I take azithromycin with blood pressure medicine?
Most blood pressure medicines, including amlodipine, ACE inhibitors and ARBs, have no important interaction with azithromycin. Diuretics need attention because they can lower potassium and magnesium.
Can I take azithromycin with hydroxychloroquine for lupus or arthritis?
Sometimes, but it needs a prescriber’s decision. Both prolong QT, so your doctor may check an ECG and your potassium and magnesium levels, or choose a different antibiotic.
Does azithromycin interact with insulin or diabetes tablets?
No important direct interaction is known. Infections and changes in eating can shift blood sugar, so check levels more often while you are unwell.
Related reading on CaresKit
- Azithromycin Side Effects
- Azithromycin Uses
- Alcohol and Azithromycin
- Missed a Dose of Azithromycin?
- Amoxicillin vs Azithromycin
- Gabapentin vs Lyrica
- Oxycodone vs Hydrocodone
Sources
- Pfizer – Zithromax Prescribing Information (drug interaction studies)
- Pfizer – Zithromax Patient Information
- FDA – Azithromycin and risk of potentially fatal heart rhythms (2013)
- CredibleMeds – QTdrugs List
- MedlinePlus – Azithromycin
- CDC – Typhoid Vaccine Information for Healthcare Providers
Medical disclaimer: This guide is not a complete list of interactions. Always ask your pharmacist or prescriber to check your full medicine list before starting azithromycin.
