Allergy diagnostics · London
Drug allergy testing & challenge - private in London
A consultant allergist-led work-up for suspected reactions to antibiotics, painkillers, anaesthetic and contrast. Skin testing, patch testing and supervised drug challenge, on one clinic pathway.
Why patients choose us
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Allergist-led work-up
A consultant allergist runs the assessment from history to challenge, not a rotating team.
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Independent by design
We never accept payment to influence which clinic we recommend. The service is free.
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A vetted London panel
Central London units with on-site resuscitation, tryptase capability and paediatric cover.
What testing involves
A systematic allergist assessment, from history to challenge.
Drug allergy testing is not a single blood test. It is a structured pathway that combines a detailed clinical history with in-vivo skin testing and, in most cases, a supervised drug challenge to confirm tolerance.
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Detailed drug history
Every previous reaction: which drug, dose, timing from first dose, morphology of the rash, associated features (breathing, blood pressure, mucosal involvement) and treatment received.
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Targeted specific IgE bloods
Where a validated assay is available, most usefully for penicillin, amoxicillin, cefaclor, chlorhexidine, suxamethonium and morphine. Blood tests alone are never sufficient.
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Skin prick testing
Drug solution placed on the forearm and pricked into the epidermis. Read at 15-20 minutes. First-line for immediate reactions.
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Intradermal testing
A tiny volume injected into the dermis at incremental concentrations. More sensitive than prick testing for immediate hypersensitivity, and read again at 24-72 hours for delayed reactions.
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Patch testing
The drug is left in contact with the skin under an occlusive patch for 48 hours and read at 48, 72 and 96 hours. Used for delayed T-cell reactions such as maculopapular rash and fixed drug eruption.
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Graded drug challenge
The definitive test. Increasing doses of the suspect drug given under close monitoring with observation for at least an hour after the therapeutic dose is reached. Only performed when skin testing and history make severe reaction unlikely.
Drugs tested
From antibiotics to biologics.
Almost any drug can be worked up, but testing is best validated for the groups below. Where a validated protocol does not exist, the allergist plans a case-by-case approach.
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Antibiotics
Penicillins, cephalosporins, quinolones, macrolides and sulphonamides. Penicillin is the most commonly mis-labelled allergy in the UK.
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NSAIDs
Aspirin, ibuprofen, diclofenac and selective COX-2 inhibitors. Cross-reactivity patterns guide alternative choice.
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Local anaesthetics
Lidocaine, prilocaine and related amide agents. True allergy is very rare and almost always excluded on testing.
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General anaesthetic agents
Neuromuscular blockers, propofol and thiopental, plus latex and chlorhexidine that often accompany theatre reactions.
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Radiocontrast media
Iodinated CT contrast and gadolinium MRI contrast. Skin testing and premedication protocols where re-exposure is needed.
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Opioids
Morphine, codeine, oxycodone, fentanyl and tramadol. Distinguishing true hypersensitivity from expected side effects.
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Chemotherapy
Platinum agents (carboplatin, oxaliplatin) and taxanes (paclitaxel, docetaxel). Desensitisation planning with the oncology team.
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Biologics
Monoclonal antibodies and infusion reactions across rheumatology, gastroenterology and oncology use.
Approach by reaction type
The pathway follows the reaction pattern.
The morphology and timing of the original reaction decide which tests are used, in what order, and whether a challenge is safe.
- 01 Immediate IgE
Hives, wheeze or anaphylaxis within an hour
Skin prick and intradermal testing to the suspect drug and cross-reactors, specific IgE where a validated assay is available, followed by a graded drug challenge to confirm tolerance.
- 02 Delayed T-cell
Maculopapular rash after several days
Patch testing plus delayed-read intradermal testing at 48-72 hours, then a prolonged oral challenge over several days under supervision.
- 03 Severe cutaneous
SJS, TEN, DRESS or AGEP
In-vivo re-exposure testing is generally contraindicated. Work-up focuses on documented avoidance, safe alternative drug lists and a medical-alert plan.
Local anaesthetic testing
"Allergic to local anaesthetic" - almost always isn't.
Many patients are labelled allergic to local anaesthetic after a vasovagal reaction (a faint), a racing heart from added adrenaline, or an anxiety-driven reaction at the dentist. True IgE-mediated allergy to modern amide local anaesthetics such as lidocaine and prilocaine is extremely rare.
A structured work-up of skin prick, intradermal and full-dose subcutaneous challenge confirms tolerance in over 97% of patients. The clinic issues a letter for your dentist, surgeon or dermatologist so future minor procedures can proceed as planned.
Typical single-visit pathway
- 1
History review
Exact symptoms, procedure context and adrenaline content of the agent used.
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Skin prick and intradermal
Preservative-free lidocaine at incremental concentrations, read at 15-20 minutes.
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Full-dose subcutaneous challenge
1-2 ml of the therapeutic agent injected subcutaneously, with observation.
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Clearance letter
Written confirmation of the agent tolerated, sent to your GP and treating clinician.
Post-anaesthesia work-up
After a reaction under general anaesthetic.
A theatre reaction usually implicates one of several agents given within minutes of each other. A structured investigation identifies the culprit and, just as importantly, the agents that are safe for any future anaesthetic.
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Acute tryptase, if possible
A serum tryptase taken 1-6 hours after the reaction supports the diagnosis of anaphylaxis. A baseline tryptase is measured at least 24 hours later or at the allergy visit.
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Timing of testing
Skin testing is performed at 4-6 weeks after the reaction, once mast cells and IgE have recovered. Earlier testing risks false-negative results.
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Skin testing to the theatre panel
Neuromuscular blocking agents (rocuronium, atracurium, suxamethonium), induction agents (propofol, thiopental), latex, chlorhexidine, opioids and any antibiotics given.
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Cross-reactivity assessment
Neuromuscular blockers cross-react in patterns that guide the choice of a safe alternative for future surgery.
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Anaesthetic team correspondence
A detailed letter goes to your anaesthetist ahead of any planned surgery, listing the culprit, the safe alternatives and the recommended intra-operative plan.
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Medical-alert documentation
A medical-alert card and, where appropriate, a MedicAlert bracelet are arranged so the information travels with you.
Cost in London
Honest ranges, not headline pricing.
Indicative ranges across our vetted London panel. Send the details of the reaction and we come back with firm quotes across two or three options.
| Package | Indicative range | Time | Turnaround |
|---|---|---|---|
| Basic drug work-up (single agent, history and skin testing) | £550-£850 | 2-3 hrs | Same day |
| Full skin testing plus graded drug challenge | £850-£1,600 | 4-6 hrs | Same day |
| Complex anaesthetic allergy panel (NMBA, latex, chlorhexidine, propofol, opioids) | £1,400-£2,800 | 1-2 half-day visits | 1-2 weeks |
| Each additional drug tested | £150-£250 | +30-45 min | Same day |
| Baseline tryptase and specific IgE panel | £120-£280 | Bloods only | 3-5 days |
Most private medical insurers cover drug allergy work-up when clinically indicated. Pre-authorisation is handled before booking.
Where in London
A short list of trusted units.
Central London clinics with allergist-led drug pathways, on-site resuscitation and access to paediatric or anaesthetic input where needed.
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The Portland Hospital Adult Allergy
HCA unit off Great Portland Street with theatre and paediatric cover on site.
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HCA The Wellington
North London hub for complex allergy including anaesthetic and chemotherapy work-ups.
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Guy's and St Thomas' Private Drug Allergy
Consultant-led NHS drug allergy service running a private pathway with tertiary anaesthetic input.
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Chelsea and Westminster Private
West London allergy clinic with same-week skin testing and challenge slots.
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London Allergy Clinic
Independent Harley Street unit with paediatric and adult allergist cover.
Frequently asked
The questions we get before someone books.
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I had a reaction to a local anaesthetic at the dentist. Am I really allergic?
Almost certainly not. True allergy to lidocaine and related amide local anaesthetics is extremely rare. Most reactions turn out to be vasovagal (a faint), palpitations from the added adrenaline, or anxiety. A skin prick, intradermal and full-dose subcutaneous challenge confirms tolerance in over 97% of patients, and the clinic writes a letter you can give to your dentist or surgeon.
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Will my insurance cover drug allergy testing?
Most UK private medical insurers (Bupa, AXA Health, Vitality, Aviva, WPA, Cigna, Healix) cover drug allergy work-up when it is medically indicated, typically after a documented reaction or before planned surgery, chemotherapy or contrast imaging. Pre-authorisation is usually required and we handle it before booking.
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Can children have drug allergy testing?
Yes. Paediatric drug allergy testing is offered from around three years upwards in dedicated paediatric allergy clinics, most commonly for beta-lactam antibiotics and NSAIDs. The approach mirrors adult testing but doses, challenge protocols and clinic environments are child-specific.
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Do I need to repeat testing later?
For most immediate IgE-mediated antibiotic allergies a negative work-up, including a graded challenge, is considered durable and does not need routine repeat. Testing may be repeated if the clinical picture changes, if a new severe reaction occurs, or before a high-risk exposure such as chemotherapy re-treatment.
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Is testing safe if I had Stevens-Johnson syndrome, TEN or DRESS?
No. Severe cutaneous adverse reactions such as SJS, TEN, DRESS and AGEP are an absolute contraindication to re-exposure testing, including graded challenge. Work-up focuses on confirming the culprit from history and timing, documenting avoidance, providing a safe alternative drug list and issuing a medical-alert card.
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I reacted to CT contrast. Can I still have future scans?
Usually yes. An allergist can skin-test to the iodinated contrast agent used and identify a safe alternative, and can advise on premedication protocols with corticosteroids and antihistamines where re-exposure is needed. Gadolinium contrast for MRI is tested separately and is a common alternative when iodinated contrast has caused problems.
Get matched to a drug allergy clinic
Tell us what happened. We come back within one working day.
A short confidential form: the drug, the reaction, the timing, and whether you have a specific procedure or treatment coming up. We match you to the right allergist and clinic, arrange the appointment and stay with you through the report.