Intramuscular injection is the primary route of administration. For patients in shock the drug may be administered intravenously.
All patients who have experienced a severe anaphylactic reaction are given a preloaded adrenaline syringe to take home, as well as instructions on its use.
Immediate readiness to treat anaphylactic reactions (adrenaline available) should be available in locations where vaccinations, desensitization therapy, allergy tests or radiographic examinations with contrast medium are carried out.
Causative agents and predisposing factors
In theory, any food (or other agent) can trigger anaphylaxis.
Strength 1:1000 (1 mg/ml), dosage for adults 0.3-0.5 ml , administered i.m. into the lateral surface of the thigh; see table T1.
Adrenaline injection can be repeated after 5-15 minutes; over one third of the patients need several doses.
To an adult patient in shock, adrenaline at strength 1:10 000 (0.1 mg/ml) can be given 0.5-1 ml slowly intravenously; for children the dose is 0.1-0.3 ml. May be repeated at intervals of a few minutes.
An intravenous adrenaline infusion is started if needed: 1 mg of adrenaline is diluted with 100 ml of 5% glucose solution. Infusion rate is 12-60 ml per hour.
Adrenaline may have reduced effect if the patient uses a beta blocker. In bradycardia and hypotension in patients using a beta blocker, the contractility of the heart can be enhanced by administering glucagon 1-5 mg i.v. in 5 minutes. The dose can be repeated.
Maintenance of vital functions
The patient should be in a half-sitting position (recumbent if hypotensive).
Make sure that the patient is breathing. Oxygen is administered through a mask if needed while monitoring the oxygen saturation.
An intravenous drip should be started with Ringer's solution or physiological NaCl solution. For a hypotensive adult, 500-1 000 ml should be given during the first hour, for a hypotensive child, 10-20 ml/kg over 15 to 30 minutes.
Blood pressure, heart rate and cardiac function should be monitored.
Intravenous glucocorticoids
For an adult methylprednisolone 80-250 mg, and for a child 2 mg/kg intravenously. Alternatively, hydrocortisone 250-1 000 mg for an adult and for a child 10 mg/kg intravenously. The total dose for a child must not exceed the dose for adults.
The effect starts slowly.
Predniso(lo)ne 30-50 mg orally, continued further for a few days (does not prevent recurrence).
Beta2-sympathomimetics
Adrenaline and glucocorticoid are effective for asthma symptoms. Use also an inhaled drug like in asthma attacks, e.g. 2.5-5 mg of salbutamol via a nebulizer.
For a child, cetirizine (age < 5 years 0.3 mg/kg, age > 5 years 10 mg)
For follow-up treatment for a few days
Follow-up
Follow-up for at least 6-8 hours is indicated even after a vanished or alleviated reaction. If needed, the follow-up may take place in a hospital. The reaction may recur (usually within 8 hours; in up to one fifth of the patients within 3 days).
When the patient is discharged, consider giving an auto-injector to take home especially if travel distances are long.
Prevention
Patients should carry a preloaded adrenaline syringe for self-treatment of anaphylaxis. This is a disposable intramuscular adrenaline injection, and the patient and family members should be taught how to use it.
The patient is advised to wear/carry a medical alert bracelet or card, especially if there have been repeated anaphylactic reactions.
Instructions for the patient in an imminent reaction: immediate intramuscular adrenaline injection into the thigh, predniso(lo)ne 20 mg and antihistamine orally
In wasp and bee allergy, specific desensitization therapy is given at the discretion of an allergologist.
Foods that might cause allergy should not be tried out by the patient at home.