Erythromycin allergy
Allergy to the antibiotic erythromycin.
About erythromycin allergy
Erythromycin is a macrolide antibiotic, a group that also includes clarithromycin and azithromycin, used for chest and skin infections and often as an alternative to penicillin. Not every problem is allergy: it is well known for causing stomach upset, nausea and cramping because it stimulates gut movement, an intolerance that is pharmacological, not immune. Genuine allergy, when it happens, involves the immune system reacting to the drug, either rapidly through IgE antibodies or through delayed T-cell responses causing rashes over days.
Allergic reactions include itching, hives, rash and swelling, and rarely more serious immediate reactions with breathing difficulty. The onset ranges from minutes to hours, with some rashes emerging after several days, in keeping with delayed skin reactions. Macrolides can occasionally cross-react, so a reaction to erythromycin may prompt caution with clarithromycin or azithromycin, though alternatives are often available.
Management means avoiding the drug where true allergy is suspected and recording it clearly, while distinguishing this from simple stomach intolerance that may not require lifelong avoidance. Tell every doctor and pharmacist so a suitable alternative antibiotic can be chosen. A suspected allergy can be assessed by a specialist rather than assumed permanent. A severe reaction with breathing difficulty, swelling or collapse is a medical emergency call 999. Never take, re-take or dose the medicine without professional advice.
Common triggers
- Erythromycin and products containing it
Symptoms
- Skin rash, hives or itching
- Swelling of the face, lips or throat
- Wheezing or difficulty breathing
- Dizziness or a drop in blood pressure
- In severe cases, anaphylaxis
Avoidance & management
- Tell every doctor, pharmacist and dentist about the allergy
- Wear a medical-alert bracelet if advised
- Check the ingredients of combination medicines
- Discuss safe alternatives with your prescriber
- Seek emergency care for a severe reaction
Sources & references
Allergy safety: what everyone should know
Mild-to-moderate reaction signs
- Itching, hives or a raised rash
- Swelling of lips, face or eyes
- Tingling mouth, sneezing, runny nose
- Stomach pain, nausea or vomiting
Anaphylaxis — call 999 (UK) or 112 (EU) immediately
- Difficult or noisy breathing, wheeze, persistent cough
- Swelling of the tongue or tightness in the throat
- Dizziness, collapse, pale and floppy (young children)
- Use an adrenaline auto-injector (e.g. EpiPen) at once if prescribed, then call an ambulance even if symptoms improve
Allergy or intolerance? A true allergy involves the immune system and can escalate quickly; an intolerance (e.g. lactose intolerance) is unpleasant but not life-threatening. The symptoms overlap, so self-diagnosis is unreliable.
Getting tested: home-testing kits based on IgG are not diagnostically valid. If you suspect an allergy, ask a GP for referral to an allergy clinic for skin-prick or specific-IgE testing and a supervised food challenge where appropriate.