Allergy shot side effects: understanding risks and benefits

Allergy shots, also known as allergen immunotherapy, are a common treatment for individuals with allergies.

While these shots can be highly effective in reducing allergic reactions over time, they may also come with certain side effects. Understanding these side effects is crucial for patients considering or undergoing allergen immunotherapy.
Allergy shot side effects: understanding risks and benefits

Common side effects


Injection site reactions:

One of the most common side effects of allergy shots is reactions at the injection site. These reactions may include redness, swelling, or pain at the site of the injection. In some cases, a small lump may also develop. These symptoms typically subside within a few hours of receiving the shot.

Allergic reactions:

While allergy shots are designed to desensitize the body to allergens, there is still a risk of allergic reactions to the shots themselves. Symptoms of allergic reactions may include hives, itching, wheezing, or difficulty breathing. Severe allergic reactions, though rare, can be life-threatening and require immediate medical attention.

Systemic reactions:

In some cases, individuals may experience systemic reactions to allergy shots, meaning symptoms occur throughout the body rather than just at the injection site. These symptoms may include nasal congestion, sneezing, coughing, headache, or fatigue. Systemic reactions typically occur within 30 minutes of receiving the shot and may require medical intervention.

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Rare side effects

While uncommon, there are certain rare side effects associated with allergy shots that patients should be aware of:


Anaphylaxis is a severe, life-threatening allergic reaction that can occur within minutes of receiving an allergy shot. Symptoms of anaphylaxis may include difficulty breathing, rapid heartbeat, loss of consciousness, or a drop in blood pressure. Anaphylaxis requires immediate medical attention and may necessitate the use of epinephrine.

Asthma exacerbation:

Individuals with asthma may experience exacerbation of their symptoms following allergy shots. This may manifest as increased coughing, wheezing, or shortness of breath. Patients with asthma should closely monitor their symptoms and report any worsening to their healthcare provider.

Managing side effects

While side effects of allergy shots can be concerning, there are steps that can be taken to manage them effectively:

Communication with healthcare provider:

It’s essential for patients to communicate any side effects or concerns with their healthcare provider. They can provide guidance on managing symptoms and may adjust the dosage or frequency of allergy shots if necessary.


In some cases, healthcare providers may recommend pre-medicating with antihistamines or other medications to reduce the risk of allergic reactions to allergy shots.


Patients should be vigilant in monitoring their symptoms following allergy shots. If they experience any concerning symptoms, such as difficulty breathing or severe swelling, they should seek medical attention immediately.
Allergy shots can be an effective treatment for individuals with allergies, but they do carry certain risks, including side effects. By understanding these potential side effects and taking appropriate precautions, patients can safely undergo allergen immunotherapy and experience relief from their allergy symptoms. Communication with healthcare providers and diligent monitoring of symptoms are key to managing side effects and ensuring the safety and effectiveness of allergy shots.

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