What Are the Signs of Anaphylaxis?

Anaphylaxis signs include hives, sweating, swelling and closing off of the airways, low blood pressure, confusion, and more. Anaphylaxis is a catastrophic allergic reaction and is a medical emergency.

Anaphylaxis is a potentially life-threatening severe allergic reaction that comes on quickly or suddenly. Common triggers for anaphylaxis include foods, medications, and insect stings. When a trigger cannot be identified, it is called idiopathic anaphylaxis.

Many people who experience anaphylaxis have known allergies and have had previous more allergic reactions, however, even people who are unaware they have an allergy can suddenly experience severe anaphylaxis.

Anaphylaxis is a potentially life-threatening medical emergency. Use your epinephrine auto-injector, and then call 911 (or have someone call for you) to get medical treatment immediately for suspected anaphylaxis.

Signs and symptoms of anaphylaxis usually begin within minutes to an hour after exposure to a trigger and include: 

• Skin reactions
  • Hives 
  • Swelling of the skin (angioedema)
  • Itching
  • Flushing 
• Eyes
  • Itching
  • Tearing
  • Eye redness
  • Swelling of the skin around the eyes
• Respiratory symptoms (common in people who also have asthma or another chronic respiratory disease)
  • Difficulty getting breathing 
  • Repeated coughing
  • Chest tightness
  • Wheezing or other sounds of labored breathing
  • Increased mucus production
• Nose, mouth, throat
  • Sneezing
  • Runny nose
  • Nasal congestion
  • Swelling of the tongue
  • Metallic taste 
  • Throat swelling or itching
  • Hoarseness
  • Change in voice
  • Sensation of choking
• Extremely low blood pressure 
  • Lightheadedness
  • Dizziness
  • Blurred vision 
  • Loss of consciousness/fainting 
• Heart
  • Weakness
  • Rapid, slow, or irregular heart rate
• Digestive system
  • Nausea
  • Vomiting
  • Abdominal cramps
  • Diarrhea 
• Nervous system
  • Anxiety
  • Confusion
  • Sense of impending doom

Anaphylaxis is caused by a severe allergic reaction to triggers such as foods, medications, and insect stings. 

Common anaphylaxis triggers include the following:

• Foods 
  • Eggs
  • Cow’s milk
  • Peanuts
  • Tree nuts
  • Fish
  • Wheat
  • Soy 
  • Crustaceans (shellfish such as shrimp) 
  • However, any food, including fruits, vegetables, seeds, spices, and food additives, can cause anaphylaxis
• Medications
  • Antibiotics (penicillins and cephalosporins) 
  • Pain relievers such as aspirin and ibuprofen (Advil, Motrin)
• Venom from insects, including bees, yellow jackets, wasps, hornets, and fire ants
• X-ray dye (radiocontrast media) given intravenously for imaging tests
• Latex from natural rubber, found in latex gloves, balloons, some condoms, sports equipment, and medical supplies
• Allergen immunotherapy (“allergy shots”)
• Exercise, either alone or after ingesting food or medication
• Less common triggers include: 
  • Human seminal fluid (semen)
  • Cold water or cold air

Risk factors for developing anaphylaxis include the following: 

• Previous severe anaphylactic reactions 
• Asthma and other chronic lung diseases 
• Other diseases, such as cardiovascular disease and coronary artery disease

Anaphylaxis is diagnosed based on symptoms that occur within minutes to an hour or so after exposure to a potential trigger.

Anaphylaxis can also resemble other health problems, such as a severe asthma attack, a heart attack, a panic attack, or food poisoning. After a patient is stabilized, additional tests may be run to rule out other conditions. 

A blood test that may be used to help confirm a diagnosis of anaphylaxis is tryptase levels, because tryptase is a natural chemical released into the blood during an anaphylactic reaction.

Anaphylaxis is a potentially life-threatening medical emergency. 

Use your epinephrine auto-injector, and then call 911 (or have someone call for you) to get medical treatment immediately for suspected anaphylaxis. Epinephrine is the ideal medicine used to treat anaphylactic reactions and is most effective when given promptly before symptoms become severe. Neither antihistamines nor asthma inhalers used to treat allergy symptoms can fully treat anaphylaxis effectively, and they should not be substituted for epinephrine.

Other treatment for anaphylaxis includes: 

• Remove known triggers 
• Go to the hospital after using your epinephrine auto-injector for evaluation, monitoring, and possibly additional treatment.
  • Up to 20% of patients with anaphylaxis have biphasic (two-phase) anaphylaxis, in which symptoms resolve and then recur without further exposure to the trigger so it is important to be monitored 
  • Additional treatment in the hospital may include: 
    • Oxygen
    • Breathing tube 
    • Extra doses of epinephrine
    • Intravenous (IV) fluids and other medications 

Complications from anaphylaxis are rare, and most patients recover completely. When complications occur, they may include the following: 

• Biphasic anaphylaxis, a second reaction without the presence of the trigger
• Low blood pressure
• Low blood oxygen 
  • Brain injury
  • Injury from a fall due to fainting 
• Irregular heartbeats (arrhythmias)
• Respiratory failure from severe bronchospasm or throat swelling
• Death, if not treated

Anaphylaxis may be prevented in some cases by doing the following: 

• Consulting an allergist for information on how to prevent allergic reactions
• Allergy testing to determine the trigger
  • Skin tests
  • Blood tests
• Avoid known triggers
  • Eliminate known food triggers from the diet
  • Avoid locations where stinging insects are seen
  • Avoid taking medications that trigger reactions
• Get allergy shots
• Wear medical identification that explains your condition and known allergies to help emergency responders provide proper care