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Macrolide antibiotics: what to be careful with

Macrolides are antibiotics used for chest, throat, skin and some stomach infections, and are a common alternative for people allergic to penicillin.

General information only, and not exhaustive. This is not medical advice, not a full list of interactions, and not a reason to start, stop or change a medicine. Interactions depend on the exact drug, the dose, your other medicines and your own health — a pharmacist or doctor is the one who decides. Always read the leaflet that came with your medicine, and ask your pharmacist before adding anything, including supplements.

Group, not a brandATC J01FA

Examples in this group: clarithromycin, azithromycin, erythromycin. Interactions usually belong to the whole group, but your own leaflet is brand-specific — always the final word.

Food and drink to be careful with

• Grapefruit juice. Clarithromycin and erythromycin already inhibit the CYP3A4 enzyme; grapefruit inhibits the same one. Together they raise the levels of anything else that depends on it.
• This group is itself the interaction. Unusually, the important point is not what food does to the antibiotic but what the antibiotic does to everything else. Clarithromycin and erythromycin raise blood levels of several common medicines — including some statins, which is why a statin is sometimes paused for the duration of the course. That pause is a prescriber's instruction.
• With or without food. Clarithromycin can generally be taken either way. Some erythromycin formulations are better absorbed on an empty stomach and others are not; the leaflet for the specific product is the answer.
• Antacids. Some macrolide formulations are affected by antacids taken at the same moment; separating them is the simple fix.

Timing around meals

Usually once or twice a day for a defined course. Spacing doses evenly matters more than tying them to meals for most products in this group.

Alcohol

No direct interaction of the disulfiram type. Erythromycin commonly causes nausea and stomach cramps, and alcohol adds to that.

Other things to watch

• Macrolides can prolong the QT interval on an ECG, which matters alongside other medicines that do the same.
• Interaction with warfarin is well described and often prompts an INR check.
• If you take a statin, a calcium channel blocker or an anticoagulant, say so when a macrolide is prescribed.

If anything here does not match what you were told, or you notice a new symptom after starting a medicine, contact your pharmacist or doctor — do not just stop taking it. Stopping some medicines suddenly is more dangerous than any food interaction.

Source: The product's own Summary of Product Characteristics and patient information leaflet, published per medicine by the licensing authority. The enzyme-inhibition interactions are listed in clarithromycin and erythromycin product information. · checked 2026-09-02

Frequently asked questions

Other medicine groups

All medicine groups · Alcohol units and clearance · Blood test reference ranges