Anaphylaxis is a severe allergic reaction that can potentially lead to death if not promptly treated. Allergic reactions typically begin suddenly after exposure to an allergen, which may be a food , medication, insect sting, or another trigger. Anaphylaxis can occur in anyone at any time; it can sometimes be triggered by allergens that a person has only had mild reactions to in the past — or to which they have never reacted to before. A mild allergic reaction may consist of hives, itching, flushing, swelling of the lips or tongue, or some combination of these.
However, throat swelling or tightening, trouble breathing, wheezing, shortness of breath, cough, lightheadedness, fainting, abdominal cramps, nausea, vomiting, diarrhea, or a sense of impending doom, are all symptoms of anaphylaxis. The symptoms of an anaphylactic reaction can vary from one episode to the next, even in the same individual.
It is important to quickly recognize anaphylaxis so it can be promptly treated with epinephrine, the first-line treatment for anaphylaxis. Epinephrine is a hormone made by the adrenal glands. It works within minutes to prevent progression and reverse the symptoms of anaphylaxis. The answer is yes. Epinephrine should be administered without delay if there is any concern or suspicion of anaphylaxis, because the risk of an untreated severe allergic reaction outweighs the risk of inappropriately receiving epinephrine.
Furthermore, delays in epinephrine administration can result in more severe reactions, and possibly even death. Individuals carrying an epinephrine autoinjector EpiPen, Auvi-Q, Adrenaclick, others should use it immediately if they suspect an anaphylactic reaction, and then call Anyone who has been treated with epinephrine after an anaphylactic reaction should be transported by ambulance to an emergency room, where they will continue to be monitored.
This is because some people who have had an anaphylactic reaction may have protracted anaphylaxis, with symptoms lasting several hours or possibly days. Others may have biphasic anaphylaxis, which is a recurrence of symptoms several hours or possibly days after symptoms resolve, even without further exposure to the allergic trigger. For both protracted and biphasic anaphylactic reactions, the first-line treatment remains epinephrine.
Biphasic reactions can occur up to three days after the initial anaphylactic reaction, which means you may develop symptoms even after being discharged from the emergency room. There is no substitute for epinephrine, which is the only first-line treatment for anaphylaxis. Neither antihistamines nor glucocorticoids work as quickly as epinephrine, and neither can effectively treat the severe symptoms associated with anaphylaxis. However, antihistamines such as diphenhydramine Benadryl or cetirizine Zyrtec , glucocorticoids like prednisone, or a combination, may be used in addition to epinephrine in some cases of anaphylaxis, after epinephrine is administered.
Antihistamines can relieve some symptoms of a mild non-anaphylactic allergic reaction, such as hives, itching or flushing, usually within an hour or two after they are given. Glucocorticoids take even longer to have an effect, so they are not useful for the treatment of any acute symptoms. As noted in anaphylaxis practice guidelines published in the Journal of Allergy and Clinical Immunology , neither antihistamines nor glucocorticoids have been shown effective in preventing biphasic anaphylaxis, so they should not be given routinely after immediate allergy symptoms have resolved.
However, some patients may benefit from a short course of glucocorticoids, for example if they had severe facial swelling or asthma symptoms related to their anaphylactic reaction.
Adrenaline injectors should be stored in a cool dark place at room temperature, but NOT refrigerated as this can damage the injector mechanism. Whilst they should be kept out of the reach of small children, adrenaline injectors must be readily available when needed and not in a locked cupboard. The shelf life of adrenaline is normally one or two years from the date of supply.
You need to regularly check the expiry date on the adrenaline injector. Patient information and support is available from the following national patient support groups for Australia and New Zealand:.
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Contact Us Locate a Specialist Sitemap. Autoimmunity Drug allergy Food allergy Food other adverse reactions Immune system Immunodeficiencies Insect allergy bites and stings Other allergies. Home Patients Allergy treatment Adrenaline for severe allergies. Adrenaline for Treatment of Anaphylaxis Anaphylaxis is a potentially life threatening, severe allergic reaction and should always be treated as a medical emergency.
Use of adrenaline in anaphylaxis assists the body's natural response The body's natural response to anaphylaxis is to release adrenaline, a natural antidote to some of the chemicals released as part of a severe allergic reaction anaphylaxis. The potential risks of NOT giving adrenaline far outweigh the potential risks of giving adrenaline If anaphylaxis is suspected, give the adrenaline injector as not giving adrenaline can be more harmful than giving it, even when it may not have been necessary.
All patients with anaphylaxis should be monitored for the possibility of recurrent symptoms after initial resolution. Laboratory testing may help if the diagnosis of anaphylaxis is uncertain. At discharge, the patient should be told to return for any recurrent symptoms. Some experts advocate a short course of antihistamines with oral corticosteroids e. A patient with a history of anaphylaxis should be instructed on how to initiate treatment for future episodes using pre-loaded epinephrine syringes.
Two strengths are available: 0. Training kits containing empty syringes are available for patient education. Family members and care-givers of young children should be trained to inject epinephrine. Written instructions should be given. The patient also may take an antihistamine at the onset of symptoms. The patient must be told to seek immediate professional help regardless of initial response to self-treatment.
If possible, the patient should avoid taking beta blockers, angiotensin-converting enzyme ACE inhibitors, angiotensin-II receptor blockers, and monoamine oxidase inhibitors, because these drugs may interfere with successful treatment of future anaphylactic episodes or with the endogenous compensatory responses to hypotension. Finally, the patient should be advised to wear or carry a medical alert bracelet, necklace, or keychain to inform emergency personnel of the possibility of anaphylaxis.
Prevention of future episodes is vital Table 6. This requires identification of the anaphylactic trigger, which is often difficult. The physician's primary tool is a detailed history of recent exposures to foods, medications, latex, and insects known to cause anaphylaxis. Previous tolerance of a substance does not rule it out as the trigger. Despite a detailed history, a cause remains elusive in many patients.
Direct skin testing and radioallergosorbent testing RAST are available for some antigens, including heterologous sera, Hymenoptera venom, some foods, hormones, and penicillin. Skin testing itself carries a risk of fatal anaphylaxis and should be performed by experienced persons only. Scratch and prick tests should precede intra-dermal testing to decrease the risk of an unexpected severe reaction.
Penicillin skin testing includes major and minor determinants; the minor determinants are more predictive of future anaphylactic events. However, it is limited to the same antigens that are available for skin testing. Both skin testing and RAST have imperfect sensitivity and specificity. Advise patient to wear or carry a medical alert bracelet, necklace, or keychain to warn emergency personnel of anaphylaxis risk.
Advise patient to keep epinephrine self-injection kit and oral diphenhydramine Benadryl for future exposures. Avoid prescribing beta blockers, angiotensin-converting enzyme inhibitors, angiotensin-II receptor blockers, monoamine oxidase inhibitors, and some tricyclic antidepressants.
Refer to allergist if causative agent or diagnosis is unclear, if in-depth patient education is needed, or if reactions are recurrent. If re-exposure to an offending medicine is necessary, administer the questionable medicine orally and observe the patient for the following 20 to 30 minutes; consider pretreatment with steroids and antihistamines.
Consider desensitization if available. When there is no choice but to re-expose the patient to the anaphylactic trigger, desensitization or pretreatment may be attempted.
Desensitization carries a risk of anaphylaxis and should be performed by experienced persons in a well-equipped location. In this procedure, the patient is exposed to gradually increasing amounts of antigen, usually via intradermal, then subcutaneous, then intravenous routes. Immunotherapy is recommended for insect sting anaphylaxis, because it is 97 percent effective at preventing recurrent severe reactions.
In situations where desensitization is not possible, pretreatment with steroids and antihistamines is an option. For a sensitive patient urgently requiring radiocontrast, 50 mg of oral prednisone 13 hours, seven hours, and one hour before contrast plus 50 mg of diphenhydramine one hour before the procedure dramatically reduce the rate of recurrent reaction.
The use of nonionic contrast media provides additional protection. Consultation with an allergist can help 1 confirm the diagnosis of anaphylaxis; 2 identify the anaphylactic trigger through history, skin testing, and RAST; 3 educate the patient in the prevention and initial treatment of future episodes; and 4 aid in desensitization and pretreatment when indicated.
Already a member or subscriber? Log in. Interested in AAFP membership? Learn more. Mary Medical Center. Address correspondence to Angela W. Tang, M. Mary Medical Center, Linden Ave. Reprints are not available from the author. The author indicates that she does not have any conflicts of interest. Sources of funding: none reported. Anaphylaxis in the United States: an investigation into its epidemiology.
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