CPR First Aid

What are the Common Symptoms of Anaphylaxis?

Anaphylaxis can be a deadly allergic reaction. This blog lists the most common symptoms of anaphylaxis.

Anaphylaxis is a potentially life-threatening allergic reaction that can cause a variety of symptoms. If you know what to look for, you can catch an anaphylactic reaction early and get treatment. In this post, we’ll discuss the common symptoms of anaphylaxis so that you can be prepared in an emergency. Stay safe!

What is Anaphylaxis?

Anaphylaxis is the most severe form of allergic reaction. When exposed to something you are allergic to, a reaction can occur within seconds or minutes and potentially be life-threatening. Anaphylaxis requires urgent medical attention. If not treated immediately, it can cause death.

Anaphylaxis often affects more than one body system. It involves the skin, respiratory, gastrointestinal, and cardiovascular systems. Anaphylaxis causes the immune system to release a flood of chemicals that can cause you to go into shock. You can tell when your blood pressure suddenly drops and you feel your pulse become rapid and weak, followed by nausea and vomiting. The airways also become narrow, blocking your breathing.

The most dangerous allergic reactions affect breathing and/or the heart and blood pressure. Take note of rash, difficulty breathing, a drastic drop in blood pressure, and abdominal or stomach pain. The signs and symptoms of anaphylaxis could happen immediately or up to the first 20 minutes after exposure. If anaphylaxis isn’t treated right away, it can be fatal. The way to treat it is by injecting epinephrine. If you don’t have epinephrine, please go to an emergency room immediately.

"Severe allergic reaction needing immediate medical care."

What are the common symptoms of anaphylaxis?

Below are some of the common signs and symptoms of anaphylaxis. The symptoms of anaphylaxis can vary. Some people’s reaction begins slowly, but in most cases, they appear rapidly and abruptly. The most severe and life-threatening symptoms are difficulty breathing and loss of consciousness. Please note that mild or moderate signs and symptoms of an allergic reaction do not always precede anaphylaxis.

• Shock

One of the symptoms of anaphylaxis is shock. A person with an allergic reaction will immediately go into shock because of the drastic changes they are experiencing in their body. It is essential to be wary of their facial expressions and body movements.

• Altered mental status 

A person going through anaphylaxis might experience an altered mental status as a symptom of a severe case of an allergic reaction. Because of the rapid drop in heart rate and blood pressure, the weakened body and brain might affect their mental state.

• Casualty may become very anxious and have a great sense of fear

The casualty may feel anxious and scared during an allergic reaction. It is normal and should not be a cause of panic. In this situation, it helps to be empathetic and knowledgeable about anaphylaxis management.

• Difficulty breathing, or shortness of breath and gasping 

One of the most common symptoms of anaphylaxis is difficulty breathing. If they are short of breath, gasping for air, and need more space than normal, stay alert and assess as this could be an allergic reaction.

• Loss of consciousness and/or collapse

Loss of consciousness is due to dangerously low blood pressure. A person can collapse due to the severity of the allergic reaction. Cardiac arrest is also one of the life-threatening symptoms. In the most severe cases, the heart can stop pumping altogether and lead to death from anaphylaxis.

• Difficulty and/or noisy breathing 

Difficulty breathing is due to swelling and/or spasms in the airways. A way to determine if a person is breathing normally is by checking the movement of their chest and if they can inhale and exhale properly. If they are breathing noisily, there is a spasm in the airway. In very rare cases, breathing can stop altogether.

• Swelling of the tongue 

Due to spasms in the airway, a person in anaphylaxis can experience swelling of the tongue or the large and small parts of the airways. Swelling of the surrounding tissues narrows the airways. It could also affect the tongue, face, eyelids, lips, throat, hands, and feet.

• Tightness in the throat 

Another symptom of anaphylaxis is tightness in the throat. Because anaphylaxis affects your breathing, the mouth to chest area will take a hit as part of the reaction. The casualty may also find difficulty in swallowing.

• Difficulty talking or hoarse voice

Hoarseness, persistent coughing, nasal congestion, wheezing, and sneezing are common symptoms of anaphylaxis. The casualty may feel chest tightness and find it difficult to speak or utter words.

• Abdominal pain or vomiting

If it’s a reaction to an insect allergy, the casualty may experience abdominal cramping. A person may feel bloated, and often, they may also have diarrhoea. Nausea and vomiting are also common symptoms of anaphylaxis.

4 Body Systems that Involve Anaphylaxis

A reaction must involve at least two different body systems to be considered anaphylaxis. The four body systems that involve anaphylaxis are the skin, respiratory, gastrointestinal, and cardiovascular systems.


Most anaphylactic reactions involve the skin. Hives are smooth, reddish bumps that can cause severe itching. Angioedema is an allergic reaction like hives, but the welts are larger and form in a deeper layer of the skin. Angioedema causes extreme swelling, usually in the face, near the eyes, and mouth. Redness, swelling, itching, and rash are common symptoms of anaphylaxis, for which people need to seek emergency medical care immediately.


Swelling of the surrounding tissues narrows the airways. Once the airway is blocked, the casualty may experience difficulty breathing, wheezing, and chest tightness. Coughing will persist because the airway is irritated, resulting in hoarseness, nasal congestion, and sneezing. Those are the body’s reactions to forcing out the air in the lungs under high pressure. A combination of these is the common symptom of anaphylaxis.


The casualty may feel a rapid or irregular heartbeat when the blood pressure drops to dangerously low levels. It results in dizziness, feeling faint or passing out, and spinning either of themselves or the surroundings. They will feel tired, weak, and off balance, and it can cause headaches. Other symptoms include chest pain or tightness, nausea, or vomiting. It can result in unconsciousness and collapse, which is a severe reaction.


The first symptom that shows often is tingling or a sensation of warmth. Anaphylaxis involves the gastrointestinal system, which results in the casualty having difficulty swallowing or digesting. It can make them feel nauseous or bloated. Vomiting, diarrhoea, and abdominal pain are also symptoms of anaphylaxis.


If you think someone is experiencing anaphylaxis, it’s essential to know how to respond. Knowing the signs and symptoms of anaphylaxis can help save a life. The best way to learn how to respond is by taking a CPR First Aid course. At CPR First Aid, we offer in-person courses across Australia, and our newest venue in Victoria is at Bendigo District RSL, 73–75 Havilah Road, Bendigo. We want everyone to have the knowledge and skills they need to help in an emergency. Book your course today and be prepared for anything!

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