Local anaesthetics allergy
Reaction to local anaesthetics such as lidocaine.
About local anaesthetics allergy
Local anaesthetics, such as lidocaine, numb a small area for dental work, stitches and minor procedures. True allergy to modern local anaesthetics is genuinely rare, despite being often reported. Many reactions blamed on the anaesthetic are in fact something else: fainting from anxiety, a racing heart or trembling from added adrenaline, or a response to another substance such as antiseptic or latex. Where genuine allergy occurs, it is more often a delayed contact-type reaction, while immediate IgE-mediated allergy is very uncommon.
Genuine allergic reactions can cause itching, hives, swelling and, at worst, anaphylaxis with breathing difficulty and collapse, reflecting the rapid onset; delayed skin reactions may appear later. Local anaesthetics fall into two chemical groups, the esters and the amides, and cross-reactivity within a group is possible, whereas the two groups do not usually cross-react. This often means a safe alternative can be found rather than avoiding local anaesthesia.
Management centres on clarifying what actually happened, since assuming a lifelong allergy can needlessly complicate dental and surgical care. Record the reaction and tell every doctor, dentist and pharmacist. Specialist clinics can test local anaesthetics and confirm which agents are safe, often by supervised challenge. A severe reaction is a medical emergency call 999. Never assume an anaesthetic is safe or unsafe without proper assessment, and follow professional advice.
Common triggers
- Local anaesthetics 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.