Neomycin allergy
Allergy to neomycin, in some creams and drops.
About neomycin allergy
Neomycin is an antibiotic found mainly in skin creams, ointments and ear and eye drops, rather than taken by mouth. Because it is applied to the skin and mucous membranes, the usual reaction is a delayed contact allergy, a T-cell response rather than the immediate IgE type. Repeated use on broken or inflamed skin raises the chance of becoming sensitised, and neomycin is a common cause of contact allergy found during patch testing.
The typical presentation is a patch of itchy, red, sometimes scaly or weeping skin where it is applied, which may be mistaken for the original problem not clearing up. Symptoms usually build over hours to days, in keeping with the delayed onset, and can spread beyond the treated area. Immediate reactions are uncommon. Neomycin can cross-react with related aminoglycosides such as gentamicin and framycetin, so a sensitised person may react to those.
Management means avoiding neomycin-containing products, which appear in various combination creams and drops, so checking ingredients or asking the pharmacist matters. Record the allergy and tell every doctor, dentist and pharmacist. Patch testing at a specialist clinic can confirm the diagnosis and identify related agents. While contact reactions are usually not dangerous, any rapid swelling, breathing difficulty or collapse is a medical emergency call 999. Follow professional advice rather than assuming a product is safe.
Common triggers
- Neomycin 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.