Allergy shots, also called allergen immunotherapy, can help people reduce their sensitivity to specific allergens over time. These shots are usually given under the skin, not into the muscle.
This raises an important question: What happens if you give an allergy shot in the muscle?
The injection site matters because allergy shots are designed to release allergens slowly into the body. Injecting the shot into muscle tissue may change how quickly the allergen is absorbed and can increase the risk of unwanted reactions.
In this guide, we’ll explain how allergy shots work, why the injection site matters, and what can happen if an allergy shot is given incorrectly.
What Are Allergy Shots?
Allergy shots are a form of subcutaneous immunotherapy (SCIT). They help the immune system become less sensitive to specific allergens.
During treatment, a healthcare provider gives small amounts of an allergen. The dose is gradually adjusted over time based on the patient’s response.
Allergy shots may be used to manage conditions such as:
- Seasonal allergies
- Allergic rhinitis
- Certain asthma symptoms
- Allergies caused by insect stings
- Other allergic conditions that do not respond well to other treatments
The goal is to reduce the body’s reaction to allergens and provide longer-term relief.
How Do Allergy Shots Work?
Allergy shots expose the immune system to small amounts of an allergen in a controlled way.
Over time, this may help the body become less sensitive to the allergen. As treatment continues, some people experience:
- Fewer allergy symptoms
- Less need for allergy medication
- Better control of allergy symptoms
- Improved quality of life
The process can take months or longer, depending on the person’s allergies and response to treatment.
Learn more about allergy shots
Why Does the Allergy Shot Injection Site Matter?
Allergy shots are designed to be injected into subcutaneous tissue, which is the layer of fat located beneath the skin.
The goal is to allow the allergen to enter the body gradually.
Muscle tissue is different. It has greater blood flow than subcutaneous tissue, which can affect how quickly a substance is absorbed.
This is why allergy shots should be given using the correct technique and at the correct injection site.
Subcutaneous vs. Intramuscular Injections
The main difference between these injection methods is where the medication or allergen is delivered.
Subcutaneous Injection
A subcutaneous injection goes into the layer of tissue just beneath the skin.
For allergy shots, this method is used because it allows the allergen to be absorbed gradually.
Intramuscular Injection
An intramuscular injection goes deeper into muscle tissue.
This method is used for certain medications and vaccines, but it is not the standard method for allergy shots.
The difference is important because the rate of absorption can affect how the body responds to the allergen.
What Happens If an Allergy Shot Is Given in the Muscle?
An allergy shot given into muscle tissue may cause several problems.
1. The Allergen May Be Absorbed More Quickly
Muscle tissue can absorb substances faster than fatty tissue beneath the skin.
With allergy immunotherapy, the goal is controlled and gradual exposure. Faster absorption may increase the risk of a stronger reaction.
2. It May Cause More Pain
Intramuscular injections can be more uncomfortable than subcutaneous injections.
A person may experience:
- Soreness
- Pain
- Redness
- Swelling
- Tenderness around the injection site
These symptoms may last longer when an injection is given incorrectly.
3. It May Increase the Risk of a Systemic Reaction
A systemic reaction affects the body beyond the injection site.
In rare cases, an allergic reaction can become serious. Symptoms may include:
- Hives
- Swelling
- Wheezing
- Difficulty breathing
- Other signs of a severe allergic reaction
This is one reason allergy shots should be given using the proper technique and under appropriate medical supervision.
4. It May Affect Treatment Effectiveness
Allergy immunotherapy relies on controlled exposure to allergens.
If an allergy shot is injected into the wrong tissue, the allergen may not be absorbed in the intended way. This could affect how the treatment works.
How Are Allergy Shots Normally Given?
Allergy shots are generally administered by a trained healthcare professional.
The injection is typically given into the subcutaneous tissue of the upper arm.
After the injection, patients are usually monitored for a period of time to watch for signs of an allergic reaction.
This monitoring is important because systemic reactions, although uncommon, can occur.
What Are the Possible Reactions to an Incorrect Injection?
An incorrectly administered allergy shot may cause local or systemic symptoms.
Local Reactions
A local reaction affects the area around the injection site.
Possible symptoms include:
- Redness
- Swelling
- Pain
- Soreness
- Tenderness
Systemic Reactions
A systemic reaction affects the body more broadly.
Possible symptoms may include:
- Hives
- Swelling
- Wheezing
- Breathing problems
- Other symptoms of an allergic reaction
A severe systemic allergic reaction can be life-threatening and requires immediate medical attention.
How to Make Allergy Shots Safer
Proper administration is one of the most important parts of allergy immunotherapy.
Follow Your Provider’s Instructions
Allergy shots should be administered or supervised by a qualified healthcare professional who understands proper injection technique.
Use the Correct Injection Site
Allergy shots are intended for the subcutaneous layer, rather than the muscle.
Using the correct injection site helps support controlled allergen absorption.
Stay for Post-Injection Monitoring
Patients are generally asked to remain under observation after an allergy shot.
This allows healthcare providers to quickly identify and treat an allergic reaction if one occurs.
Tell Your Provider About Any Symptoms
After receiving an allergy shot, let your provider know if you notice unusual symptoms.
Do not ignore symptoms that appear to be getting worse.
How Effective Are Allergy Shots?
Allergy shots can provide long-term benefits for people with certain allergies.
The treatment works by gradually exposing the immune system to specific allergens. Over time, this may reduce the body’s sensitivity and lessen allergy symptoms.
Some people may also need less medication to control their symptoms.
The amount of improvement varies from person to person. Your allergy specialist can determine whether immunotherapy is appropriate based on your symptoms, medical history, and allergy test results.
Allergy Testing Before Immunotherapy
Before starting allergy shots, an allergy specialist may recommend an allergy test.
Testing can help identify the allergens that trigger your symptoms.
The results can help your healthcare provider determine which allergens should be included in your immunotherapy treatment.
Learn more about allergy testing
An allergy evaluation may be especially important for people with significant allergy symptoms or allergies that affect their breathing and daily activities.
What Should You Do If an Allergy Shot Was Given in the Muscle?
If you believe an allergy shot was accidentally injected into muscle tissue, tell the healthcare provider who administered the injection.
Do not assume that everything is fine simply because you do not have symptoms right away.
Your provider can determine whether additional monitoring or treatment is needed based on the injection, your allergy history, and any symptoms you experience.
If you develop signs of a severe allergic reaction, seek emergency medical care immediately.
Key Takeaways
- Allergy shots are typically given into subcutaneous tissue, not muscle.
- The correct injection site helps control how the allergen is absorbed.
- An injection into muscle may cause more pain or change the rate of absorption.
- Incorrect administration may increase the risk of an allergic reaction.
- Patients should follow their provider’s instructions and remain under observation after allergy shots.
- Allergy testing can help identify the allergens that may be treated with immunotherapy.
- Allergy shots should be administered by a trained healthcare professional.
Get Expert Help for Your Allergies
Allergy shots can be an effective long-term treatment for people who struggle with certain allergies. However, proper administration is essential for safety and effectiveness.
If you are considering allergy immunotherapy, an allergy specialist can evaluate your symptoms, perform appropriate allergy testing, and determine whether allergy shots are right for you.
Explore Enticare Allergy Services
Ready to find out if allergy shots are right for you?
Schedule an appointment with Enticare’s allergy specialists today and take the next step toward better allergy control.