ASCIA PCC Antibiotic Allergy Challenges FAQ174.97 KB

Q 1: What is an antibiotic allergy challenge?

When antibiotic allergy is uncertain, skin testing and/or a medically supervised antibiotic allergy challenge can be conducted to confirm or exclude antibiotic allergy.

An antibiotic allergy challenge is a procedure where doses of the suspected antibiotic are given, either as a single dose or as graded dosing, starting from a small dose and increasing the amount of drug in 2-3 steps. This procedure can take up to 3 hours, or longer if a reaction occurs. The challenge is conducted by specialist nurses under medical supervision to observe for reactions, usually by a clinical immunology/allergy specialist, or other medical specialist.

Q 2: Why are antibiotic allergy challenges performed?

There is increasing evidence that most people who are labelled as allergic to antibiotics may not actually be allergic to the antibiotic. This can have a negative impact on people with unconfirmed allergy, as it may lead to treatment with less effective antibiotics that may have more side effects.

Antibiotic allergy challenges are therefore important, as they are used to confirm if a person with suspected antibiotic allergy is truly allergic. If a person is confirmed to have an antibiotic allergy, the challenge may also determine the type of reaction.

Q 3: What are the different types of reactions to antibiotics?

• An allergic reaction to an antibiotic is called ‘immediate’ when it occurs within one to six hours after taking a medication, or ‘non-immediate’ when the reaction occurs after 24 hours of starting a medication.
• Mild or moderate allergic reactions to an antibiotic can result in symptoms such as itchy rashes (hives) and swelling (angioedema). Rashes due to infection can be mistaken for an allergic reaction and sometimes the combination of a viral illness and antibiotic administration can cause a rash, whereas when the drug is used for its correct indication (a bacterial infection), there is no rash.
• Severe non-immediate rashes are associated with fever, flu-like or other systemic symptoms, and can be life-threatening. These are called severe cutaneous adverse reactions and require urgent specialist care.
• Severe immediate allergic reactions (anaphylaxis) to antibiotics affect breathing, the heart, and blood pressure. Anaphylaxis can be life threatening and requires urgent medical attention. Anaphylaxis due to antibiotic allergy is more likely when medication is given by an injection, than if it is taken orally.

Q 4: How do you prepare for an antibiotic allergy challenge?

It is important that the person being challenged:

• Is in good health for the antibiotic challenge to go ahead. If the person being challenged feels unwell prior to their appointment, contact the clinic to reschedule the challenge.
• Has not suffered from wheezing in the week prior to the challenge, if they have asthma. If in doubt, contact the clinic the day before the appointment to discuss this.
• Understands the antibiotic challenge process:
• Most people will have the oral challenge, which means the antibiotic is given into the mouth to observe for reactions. This is usually done in 2-3 steps.
• Skin testing may be performed in people with a history of an immediate reaction before they are challenged.
• An intravenous (IV) challenge (through the vein) may also be performed in cases where the person has had a prior reaction to an IV antibiotic.

Q 5: Who requires skin testing before they can have an antibiotic allergy challenge?

People with a history of an immediate reaction to an antibiotic will usually have skin testing performed prior to the oral challenge:

• Skin testing is where a small amount of antibiotics is ‘pricked’ and then injected into the top layer of the skin on the forearm to observe for reactions.
• The oral challenge will only proceed if there is no reaction to the skin testing.

These tests occur under the supervision of medical staff who are trained in handling the unlikely event of a severe immediate allergic reaction (anaphylaxis).

Q 6: How are reactions managed during an antibiotic allergy challenge?

If a reaction occurs during the challenge, the doctor will be consulted and a decision on continuing or stopping the challenge will be discussed. One of the following outcomes will be determined:

• If reactions are transient (very mild), the challenge may continue.
• If reactions are mild, the challenge may stop or continue.
• If there is a severe, immediate allergic reaction (anaphylaxis), adrenaline (epinephrine) will be given and the person with anaphylaxis will stay in hospital to be monitored for a minimum of four hours.

After the antibiotic challenge the supervising doctor or nurse will give you information on what to do at home.

Note: If an antibiotic allergy challenge is performed in a controlled medical environment with medical and nursing staff experienced in treating anaphylaxis, the way an allergic reaction is treated in a hospital may vary from the instructions on the ASCIA Action Plan for Anaphylaxis. This is because hospital staff have ready access to blood pressure and oxygen checks, oxygen masks and other equipment.

It is important to follow instructions on the ASCIA Action Plan when not in a hospital setting.

Q 7: What happens if no reaction occurs in the antibiotic allergy challenge?

If a person does not have a reaction in the antibiotic allergy challenge, they they may be advised to go home to complete a 3-5 day course of the antibiotic they are suspected to be allergic to, as sometimes delayed reactions can occur.

Q 8: What happens if a true antibiotic allergy is diagnosed?

If a true antibiotic allergy is diagnosed after a skin test or challenge:

• The antibiotic must be avoided.
• The antibiotic allergy needs to be recorded in hospital, GP and specialist records and where possible, uploaded to the person’s My Health Record.
• A green ASCIA Action Plan for Drug (Medication) Allergy* and Drug Allergy Record should be completed by your doctor. These forms are available online at www.allergy.org.au/drug-allergy
• Carrying or wearing of medical identification should be considered.
• It is not usual to prescribe an adrenaline injector (such as EpiPen^® or Anapen^®) for a drug allergy.

* If a person already has a red ASCIA Action Plan for Anaphylaxis for other allergies, their antibiotic allergy can be added to that plan.

© ASCIA 2022

ASCIA is the peak professional body of clinical immunology/allergy specialists in Australia and New Zealand.

ASCIA resources are based on published literature and expert review, however, they are not intended to replace medical advice. The content of ASCIA resources is not influenced by any commercial organisations.

For more information go to www.allergy.org.au

To donate to immunology/allergy research go to www.allergyimmunology.org.au

Fast Facts about drug (medication) allergy can be found here:
www.allergy.org.au/patients/fast-facts/drug-allergy

Adverse Reactions to Alternative Medicines

Allergic Reactions to Aspirin and other Pain Killers 

Antibiotic Allergy Challenge FAQ New March 2022

Chlorhexidine Allergy

Sulfonamide Antibiotic Allergy

Content updated March 2022

ASCIA PCC Allergic reactions aspirin other pain killers 201967.4 KB

Aspirin has long been used to reduce pain from inflammation (redness and swelling), injury, and fever. Although it was originally isolated from plants in the early 1800s, aspirin is now made synthetically. A number of similar synthetic non-steroidal anti-inflammatory drugs (NSAIDs) have been introduced. 

How do aspirin and NSAIDs work?

Aspirin and NSAIDs work by inhibiting an enzyme in the body called cyclo-oxygenase-1 (COX1) which produces compounds known as prostaglandins. These prostaglandins are involved in tissue inflammation, pain and fever. Aspirin also inhibits the activity of blood elements known as platelets (which help clotting), thus helping to prevent blood clots, and reduce the risk of heart attacks and strokes. There is recent evidence that aspirin may even reduce the risk of bowel cancer.

Aspirin may have side effects

Common side effects of aspirin include bruising and stomach upset. Less commonly, a stomach ulcer or stomach bleeding may occur. Very high doses of aspirin may cause confusion or ringing in the ears (tinnitus). Aspirin should be avoided in children, as it can trigger Reye's syndrome, a condition with liver inflammation and brain swelling.

Aspirin and allergy

Aspirin can cause allergic reactions in some people. Symptoms include flushing, itchy rashes (hives), blocked and runny nose and asthma (sometimes severe), usually within an hour of taking a tablet. If you have hives (urticaria), nasal polyps or asthma, your risk of aspirin allergy is 10-30% compared to 1% in people without these conditions. These reactions can also be triggered by non-aspirin NSAIDs.

The presence of aspirin is not always obvious

Aspirin or other NSAIDs may be present in many over-the-counter painkillers and may be found in:

• Medications for headache, period pain, and sinus pain.
• Cold and flu tablets.

Some people who are highly aspirin-sensitive may need to avoid other salicylates which may be found in:

• Inflammatory bowel disease drugs.
• Complementary alternative medicines such as willow tree bark extract and some herbal arthritis pills.
• Topical salicylates such as arthritis creams and teething gels.

If you are sensitive to aspirin, you will need to carefully read medicine labels and be cautious about taking any pain killer without talking to your doctor or pharmacist first.

Most people who are allergic to aspirin and NSAIDs can safely take paracetamol and/or codeine.

There are many brands of NSAIDs

As there are so many brand names of the same medication, and so many types of medications available, accidental exposure to aspirin or NSAIDs may occur. Therefore it is important to tell your pharmacist or health professional about your sensitivity to these medicines.

Testing for drug sensitivity

There is no reliable blood or skin allergy test for confirming or excluding sensitivity to aspirin and NSAIDs. The only way to do so is a graded open challenge under strict medical supervision. Challenge testing is not always necessary, but may be advised in some circumstances to prove that sensitivity exists, or to prove the safety of an unrelated medicine, so that you have another drug from which to choose if you need to use a pain killer.

What is aspirin desensitisation?

This is useful in some people with aspirin allergy, nasal polyps and asthma. It can be used to:

• Improve asthma control.
• Reduce the severity of sinusitis/nasal polyposis.
• Reduce the rate at which polyps regrow.
• Enable people to use aspirin or similar medication for treatment of heart disease or arthritis.

Side effects can include:

• Stomach irritation such as ulceration and bleeding at high doses.
• Easy bruising (common).
• Tinnitus (ringing in the ears, a rare side effect).
• Potential significant exacerbation of asthma.
• Anaphylaxis.

The decision to undertake aspirin desensitisation should be made in consultation with a clinical immunology/allergy specialist.

Management of aspirin / NSAID sensitivity with ongoing hives

If you have ongoing hives (urticaria), you should avoid aspirin and NSAIDs unless you know that you can tolerate them without a problem. If you are already taking regular aspirin (for example, to prevent heart attack or stroke), or a regular arthritis tablet for the treatment of pain, then you do not need to stop taking this medicine unless your hives clearly get much worse after taking the medicine.

Severe allergic reactions after taking a pain killer

Many people have cross-reactive allergy to aspirin and other NSAIDs. However, some people with NSAID allergy are sensitive to only one drug. If you have had an allergic reaction to one type of NSAID, a challenge with a different drug can be considered if you need to take aspirin or an anti-inflammatory medication for the treatment of arthritis.

Tolerability of some NSAID medications

Some NSAIDs such as celecoxib and meloxicam predominantly inhibit the cyclo-oxygenase 2 (COX2) enzyme rather than COX1, and therefore can be taken safely by many patients (but not all), who have aspirin and NSAID sensitivity. If you need to take one of these medications for arthritis, it would be best to consult a clinical immunology/allergy specialist.

Dietary salicylates in aspirin-sensitive patients

Some people who have urticaria or asthma and nasal polyps suffer symptoms if they eat foods that have high levels of natural salicylates. Low salicylate diet trials may occasionally be recommended but are not considered a routine part of management.

Updated April 2019

ASCIA PCC Sulfonamide antibiotic allergy 201983.68 KB

Sulfonamide antibiotics can cause allergic reactions that range from a mild rash to a severe blistering rash, through to anaphylaxis, which is the most severe type of allergic reaction.

This document uses spelling according to the Australian Therapeutic Goods Administration (TGA) approved terminology for medicines (1999) in which the terms sulfur, sulfite, sulfate, and sulfonamide replace sulphur, sulphite, sulphate and sulphonamide. 

Sulfonamide antibiotic allergy

A person that is allergic to one sulfonamide antibiotic, is at risk of reacting to other sulfonamide antibiotics. Sulfonamide antibiotics that are available on prescription in Australia include:

• Sulfamethoxazole that is used in combination with trimethoprim.
• Less commonly used sulfonamide antibiotics such as sulfadiazine (tablets, injections or creams), sulfadoxine (for malaria), and sulfacetamide antibiotic eye drops.
• Sulfasalazine (Salazopyrin, Pyralin), that is used in inflammatory bowel disease or arthritis, and is a combination sulfapyridine (a sulfonamide antibiotic) and a salicylate.

If a person has had an allergic reaction to Bactrim, Resprim or Septrin, there is no way of knowing whether the allergy was to sulfamethoxazole or to trimethoprim. Therefore trimethoprim (Alprim, Triprim) and sulfonamide antibiotics should both be avoided.

Sometimes people who have had an allergic reaction to a sulfonamide antibiotic are labelled as "sulfur allergic" or allergic to sulfur, sulphur or sulfa. This wording should not be used since it is unclear and can cause confusion. Some people wrongly assume that they will be allergic to non-antibiotic sulfonamides or to other sulfur containing medicines or sulfite preservatives.

Sulfur is an element which occurs throughout the human body as a building block of life, and it is not possible to be allergic to sulfur itself. Allergic reactions to sulfonamide antibiotics do not increase the likelihood of allergy to sulfur powder, sulfite preservatives, sulfates (in medicines, or soaps and shampoos) or non-antibiotic sulfonamide medicines like some pain killers or fluid tablets.

Other types of sulfur containing substances

Elemental sulfur powder is commonly used in gardening, and while irritation may occur from skin contact or inhalation, allergy has not been described.

Sulfates are in some injectable drugs as sulfate compounds, such as heparin sulfate, dextran sulfate, morphine sulfate. The sulfates in soaps (such as sodium lauryl sulfate) are strong detergents and can irritate the skin or eyes. However sulfate itself does not cause allergic reactions. It is usually safe to use a sulfate when a person has a sulfonamide allergy or a sulfite intolerance.

Sulfite preservatives are commonly known as sulfur dioxide and metabisulfites, with preservative numbers 220-228. Sulfites can be used to preserve flavour and colour within food, inhibit bacterial growth, stop fresh food from spoiling, and help preserve medication. Sulfites are most often found in wine, dried fruit, and dried vegetables. Sometimes they are used in sausages and salads. They can also occur naturally in low concentrations. Sulfites can cause adverse reactions which are like allergy but do not involve the immune system and are therefore called intolerances. The most common reactions are asthma symptoms (in people with underlying asthma) and rhinitis (hay fever-like) reactions. Occasionally urticaria (hives) may occur, and very rarely, anaphylaxis (severe allergic reaction). 

There is no relationship between sulfite sensitivity and sulfonamide antibiotic allergy.

Non-antibiotic sulfonamide medicines such as some fluid medicines, diabetes medicines and arthritis medicines contain sulfonamide components but these are not sufficiently similar to sulfonamide antibiotics to pose an allergy risk. These medicines do not need to be avoided by people who are allergic to sulfonamide antibiotics because the allergy rarely cross-reacts.

Confirming the diagnosis

There is no blood test available for allergy to sulfonamide antibiotics, and skin testing has not been validated. Skin testing has been used to check for trimethoprim allergy (to distinguish from sulfamethoxazole allergy in people who have reacted to Bactrim) but results need to be interpreted with caution. Challenge testing may be carried out under supervision of a clinical immunology and allergy specialist.

Management

People who have had an allergic reaction to one sulfonamide antibiotic are usually advised to avoid all sulfonamide antibiotics. As these antibiotics are not normally used in an emergency, wearing medical identification is not routinely recommended although it may be advisable in people who have had anaphylaxis.

Sulfonamide antibiotic allergy is not always lifelong and cross-reaction does not always occur. Desensitisation to switch off allergy temporarily, is available if a sulfonamide antibiotic is the only suitable drug to use.

© ASCIA 2019

ASCIA is the peak professional body of clinical immunology/allergy specialists in Australia and New Zealand.

ASCIA resources are based on published literature and expert review, however, they are not intended to replace medical advice. The content of ASCIA resources is not influenced by any commercial organisations.

For more information go to www.allergy.org.au

To donate to allergy and immunology research go to www.allergyimmunology.org.au/donate

Updated April 2019