In short, a drug challenge is when a child is administered a medication under controlled settings and in a safe child friendly environment. The medication may be given in incremental stages (incremental challenge) or as one amount (cumulative challenge). If this stage is negative, then doses are typically taken at home on sequential days.
Your child would have been seen by a paediatric allergy consultant for The Portland Hospital or other referring doctor and would have undergone a thorough assessment (history, medical examination, and where available, allergy tests). A decision would then have been made to proceed to the drug challenge.
There are many reasons why a drug challenge may be performed, two common scenarios include; many children will at the time of an infection develop non-specific rashes and swelling or if an antibiotic and anti-inflammatory medication e.g. ibuprofen is prescribed at the same time this commonly gives rise to a suspicion of drug allergy to one or both medications. Allergy testing (skin tests and or specific lgE) is poorly predictive for most drugs and so a drug challenge is required to accurately make a diagnosis.
Children undergoing dental treatment are understandably anxious and prone to becoming pale and even fainting when in the dental chair; if a local anaesthetic has been administered this may give rise to a suspicion of local anaesthetic allergy. This is best resolved by administering the medication in a drug challenge.
The drug challenge will be carried out in a safe setting and by an experienced allergy nurse, providing specialist nursing care to ensure any allergic reaction would be responded to quickly. The medication is given slowly to the child through small increments.
What happens if my child does react to the drug? The specialist nurse who is looking after your child is very experienced and skilled at recognising the signs and symptoms of an allergic reaction. If your child starts to experience any suggestive allergy symptoms e.g. significant behavioural changes, new-onset wheeze or cough, hives, itching, red rash or swelling, then the challenge will be stopped and an anti-histamine, and/or Ventolin and/or epipen will be administered. This will be recorded as a ‘positive drug challenge’ i.e. your child is allergic to the medication. Your child will then need to remain under observation by the specialist nurse for between 1-2 hours post the reaction or until all symptoms of a reactions have ceased. The specialist nurse will then recommend continued avoidance of the medication and possible alternatives.
If, during the challenge, your child complains of not feeling well, but does not have any observable physical reactions to the drug, the specialist nurse will discuss with you and your child the need to either repeat the dose they have just had administered or move onto the next increment. Any concerns during the process will be communicated to the covering Consultant.
In the likely event that your child does not react to the drug being tested, the specialist nurse will be able to administer all the increments of the medication in no less than
30 minute intervals. Your child will be encouraged to play in between increments and there is a play room and a play specialist in the area the challenge is being carried out. Once all the drug has been administered, your child will continue to be observed for up to 2 hours after the last dose of the drug has been administered. The observation period is required as there can be a delayed reaction. If after a safe observation period, your child has not had an allergic reaction the specialist nurse will record the challenge as a negative challenge and will give advice on whether the medication can be used in the future.
After the supervised challenge
If an oral drug is being challenged, you will be given a subsequent course (typically 3 days) of the medication to continue to take whilst you are at home.
If any rashes appear while you are at home, it is best to take an image of the rash and electronically return the image to the specialist nurse. The images will be discussed with the allergy consultant and you will be contacted with further advice.
You may be recommended to return to see the consultant in clinic post challenge. The email address for any returned images is [email protected] and [email protected]
The risks of a severe reaction are very small and do not often occur. The specialist nurse will take your child’s consent as you are admitted to the unit.
The most frequent risks are that your child may experience a mild to moderate allergic reaction requiring the administration of anti-histamines and asthma medications (if needed). Such a reaction may also involve itchy hives, itchy red rash, swelling of the face or lips, behaviour change, new- onset of wheeze or cough or vomiting.
Delayed, non-specific rashes may also occur at home with subsequent intake. Severe reactions at home, after tolerating the first supervised doses, are extremely rare.
Anaphylaxis is the most serious type of an allergic reaction which can involve problems with your child’s breathing and/or blood pressure. They may proceed with a wheeze, trouble with talking in sentences or become floppy or drowsy. If this was to happen the specialist nurse will administer an adrenaline auto injector. The Portland Hospital has an onsite Paediatric Intensive Care Unit (PICU). In the unlikely event that the primary interventions do not settle the severe allergic reaction, the attending PICU doctor will always assess your child.
What if my child refuses to take the medication? This is uncommon. Nonetheless, the specialist nurse will ask you to bring with you any food that you know your child can tolerate, is not allergic to, and likes to eat. This can be used as a vehicle to mix or ‘blind’ being tested. The specialist nurse will be used to encouraging children to take medications and will work closely with you and your child to ensure that enough of the medication is taken to ensure a clear diagnosis of a positive or negative drug challenge.
Your doctor would have generated a referral for the drug challenge; if your doctor is not an allergy specialist then one of our Portland Hospital allergy specialists will vet the referral. If you are self- paying the specialist nurse will immediately be able to book a convenient date with you.
If you are claiming through an insurance company, you will need to speak to your insurance company to obtain a pre-authorisation number for the drug challenge test. It is important that your insurer understands that a drug challenge is the gold standard diagnostic test for drug allergy and we are able to provide you with supporting documentation to assist with insurer pre- authorisation.
24 hours before the challenge the specialist nurse will contact you to complete a pre-challenge telephone assessment with you.
My child takes regular medications; do I need to stop these?
If your child is unwell in any way or has asthma and needs to use their blue inhaler frequently then it may be necessary to reschedule the appointment. Likewise, severe hay fever symptoms may confuse the challenge outcome and would require anti- histamines. During this pre-challenge telephone conversation, the specialist nurse is able to answer any questions that you may have.
If your child takes a regular long acting anti- histamine such as Cetirizine they will need to stop this 7 days prior to the challenge appointment.
If your child takes regular short-acting antihistamine such as Piriton they will need to stop this 2 days prior to the challenge appointment.
If your child is requiring their Salbutamol inhaler regularly due to his/her asthma is may be necessary to reschedule the drug challenge appointment.
If your child takes Montelukast, a nasal spray (such as Nasonex or Avamys) or a preventer inhaler (Clenil, Beclomethasone, Flixotide, Symbicort) these medications may continue to be taken as usual.
Please make the specialist nurse aware of any other medications your child may be taking during the pre-challenge telephone call as some medications do contain small amounts of anti- histamine and these may also need to be stopped before the drug challenge.
If your child had a negative drug challenge the specialist nurse will usually ask you take a further 3 days’ worth of the medication at home. If rashes or reactions were to occur during these 3 days we would ask you to return any images to [email protected] and [email protected]
The specialist nurse will contact you within 48-72 hours post the drug challenge to ensure your child has remained well and you both have no further questions. If during this time, or over a weekend, you have any concerns or queries please contact The Portland Hospital’s main switchboard on 020 7580 4400 and ask to speak to the Paediatric Bleep Holder, who will take your details and get back to you as soon as possible. If you are worried that your child is having an allergic reaction, please contact your GP, or in an emergency please dial 999 and seek urgent medical attention.
General Information/ Frequently Asked Questions
COVID-19
-Patients are due to have two negative COVID 19 swab before admission.
-Covid 19 swab tests needs to be done at 7-9 days and 3 days before admission at The Portland Hospital.
-Please limit contact with groups of people outside of household bubble and maintain social distancing prior to admission.
-Only one parent/guardian is allowed on admission for the challenges.
-Patient and parent/ guardian wear a face-covering or mask on admission.
Q. How long does the cumulative or an incremental allergy challenge take?
A. On average a cumulative challenge will last between 2-4 An incremental challenge will last between 4-6 hours.
Q. How can we reduce anxiety in our child prior to admission?
A. Before admission have a look at our website, bring in toys and familiar items your child likes having with them, and even some rewards for your child to be given during the A play area and play specialist will be available to speak to you and your child.
Q. Can we introduce more than one food during the challenge?
A. Please discuss with your consultant and the specialist Generally, we prefer to introduce a single food as this gives a clear indication of which food your child has or has not reacted to.
Q. Should I give my child breakfast before the challenge?
A. Please only give a moderate portion of what your child would normally The hungrier your child is at the start of the challenge, the more likely they are to give the new food a try.
Q. If my child reacts during the challenge what other food can they then eat?
A. Bring some food with you that you know your child is not allergic to and enjoys, then if they need to snack on something after the challenge they can.
Q. Do I need to bring my child’s emergency medications?
A. Please bring all your regular allergy medications with you, this will also cover you for your journey home post the challenge.
Q. Where is the hospital?
A. The challenge service is based in the Daycase Unit at The Portland Hospital, Ground Floor, 205-209 Great Portland Street, London, W1W 5AH. Please arrive 15 minutes before your appointment.
Q. What is the cost of the allergy test and how do I arrange payment?
A. The cost of the incremental challenge is £1,639. If you are covered by insurance, then you will need to come to your challenge with your pre- authorisation number. If you do not have your pre- authorisation number, you will need to pay on the day and claim back from your insurance company retrospectively.
Q. Where can I park?
A. Visitors have the option of two car parks close by to the hospital; the NCP in Carburton Street or Union Carparks in Devonshire Row There is also meter parking in the surrounding streets. The forecourt of the hospital is available for arrival and collection of patients only.
Clinic contacts:
Allergy Consultants:
Dr Du Toit
Professor Lack
Dr Brough
Dr Cox
Dr Boyle
Allergy Clinical Nurse Specialist:
Melanie Davies
Louise Cameron
