Allergy on the CCFP exam

Approach

• Ask about allergies at the first visit and before every new prescription.
• Record the drug, why it was given, what happened, and how soon after the dose.
• Record how the reaction was treated, and whether the drug was stopped.
• Ask if the same drug was taken again later. A patient who tolerated a later course is not allergic to it.
• Update the entry when new facts arrive, such as a tolerated test dose. Remove a label that testing disproves.
• Have an allergist recheck a child's confirmed penicillin allergy after 5 years. Children can outgrow it.
• A wrong label has a cost: second-line antibiotics, longer hospital stays and resistant infections.

Approach

• Time it. Immediate, antibody-driven (IgE) reactions usually start within 1 hour of a dose.
• Most mild, late rashes in children come from the infection. They do not stop you giving penicillin later.
• Ask about danger signs of a serious late reaction: fever, joint pain, swollen glands, peeling skin, mouth or eye sores.
• Separate side effects, such as nausea, from allergy. Illness and side effects are often mislabelled as allergy.
• A parent's or sibling's penicillin label has not been shown to raise the child's risk.
• Low-risk history: give one amoxicillin test dose of 15 mg/kg and watch for 1 hour. No skin test first.
• Cephalosporins: cross-reactivity is about 2% in true penicillin allergy and under 1% in unconfirmed labels.

Approach

• Anyone who has had anaphylaxis carries epinephrine. No other drug takes its place.
• For hives and itch, use a newer non-sedating antihistamine. Avoid diphenhydramine: it sedates and dulls thinking.
• Antihistamines and asthma puffers are add-ons. They do not stop anaphylaxis.
• Confirm suspected asthma with a breathing test, such as spirometry, in anyone over 6 before long-term treatment.
• Large swelling around a sting: cold packs, a non-sedating antihistamine and pain relief. A short oral steroid only if severe.

Approach

• Prescribe one after any sting reaction that reached the gut, breathing or circulation.
• Not needed for large swelling around the sting, or for hives alone after a sting.
• Devices come in 0.15 mg and 0.3 mg. Use 0.3 mg once a child weighs more than 25 kg.
• Teach the child, the family and caregivers how to use it.
• There is no reason to withhold epinephrine in a systemic reaction.

Approach

• Teach the signs by body system: hives or swelling, vomiting or cramps, wheeze or cough, faintness.
• Show how to use the device, and have the patient or parent show it back.
• Anyone who uses the device goes to an emergency department. Watch there for at least 4 to 6 hours.
• Give a written anaphylaxis action plan. Review avoidance steps at follow-up visits.
• Remind families that no condition makes epinephrine unsafe in a systemic reaction.

Approach

• After a systemic reaction, advise a MedicAlert bracelet or other medical ID.
• Pair it with an action plan posted for school or child care staff.
• A low-risk rash needs a test dose, not a bracelet. Most children labelled penicillin-allergic tolerate it when tested.
• No ID for a label that a tolerated test dose has removed.

Approach

• Hives with vomiting or cramps after a sting is a systemic reaction. Give epinephrine; do not wait for wheeze.
• Give epinephrine into the muscle: 0.01 mg/kg, up to 0.3 mg before puberty and up to 0.5 mg in teens.
• Antihistamines treat itch and hives only. They do not replace epinephrine and can delay it.
• Add an inhaled bronchodilator for wheeze that persists after epinephrine.
• Watch in the emergency department for at least 4 to 6 hours.
• Consider watching longer after a late arrival, repeat epinephrine, or a bronchodilator in the department. A wide pulse pressure (a large gap between the top and bottom blood pressure numbers) counts too.
• Steroids are often given to prevent a second wave. Evidence for that is lacking, and they do not replace observation.

Approach

• Refer to an allergist to find the trigger. The history decides which foods or drugs to test.
• Do not order food IgG panels. A positive IgG shows past exposure, not allergy.
• Order specific IgE tests only for triggers the history points to. People can have IgE to foods they eat safely.
• After severe anaphylaxis in a child or teen, above all with low blood pressure or no hives, a baseline tryptase (a mast-cell blood marker) is drawn.
• In children, after a systemic sting reaction, venom immunotherapy (allergy shots of venom) cuts the risk of another from about 30% to about 5%. The shots usually run 3 to 5 years.

Approach

• Write an anaphylaxis action plan and post it for daycare or school staff.
• Teach the child, the family and caregivers the signs and how to give the device.
• Use the 0.3 mg device once the child weighs more than 25 kg.
• Review avoidance and the plan with the family at follow-up visits.

Approach

• Ask when symptoms happen: by season, at work or school, at home, or near pets.
• Symptoms that ease away from one building point to something in that building.
• History and examination are the main tools for diagnosing allergic rhinitis.
• Skin prick testing is the main way to find the trigger. Test allergens from the patient's surroundings, such as pollen, animal dander, moulds or dust mites.
• Confirm suspected asthma with spirometry or a methacholine test (an airway challenge test) in anyone over 6.
• Most acute sinus symptoms are viral. No antibiotics for mild, uncomplicated sinusitis.
• Treat allergy symptoms with a non-sedating antihistamine, not diphenhydramine.