Patient education: Allergy shots (The Basics)

What are allergy shots? — Allergy shots are a treatment that can make you less likely to have allergy symptoms. The name doctors use for allergy shots is "allergen immunotherapy." That's because the shots change the way your immune system reacts to allergens. Allergens are the things that you are allergic to.

Allergy shots are usually made to order, just for you. They contain tiny amounts of allergens, such as pollen or mold. If you are allergic to stings from bees or other insects, allergy shots can lower your chances of having a dangerous reaction to a sting in the future.

Allergy shots work for allergies to:

●Pollen from trees, weeds, and grasses

●Mold spores in the outside air

●Cat or dog "dander" (tiny flakes of fur, hair, and skin)

●Dust mites (tiny insects found in dust)

●Stings from honeybees, yellow jackets, hornets, wasps, and (in some areas) fire ants

Allergy shots are not used to treat allergies to food, latex, or medicines.

Why do I need allergy shots? — If you have allergies, you should avoid pollen, molds, and other things that cause your allergies. You can also take allergy medicines. But if those treatments don't work well enough, your doctor might recommend allergy shots. Also, in children with nasal allergies, allergy shots can help prevent asthma later in life.

Your doctor will also recommend allergy shots if you had a serious allergic reaction to a sting from a bee or other insect. Symptoms of a serious allergic reaction, called "anaphylaxis," include:

●Flushing, when your skin turns red and feels hot (especially on your face)

●Hives, which are red, raised, red patches of skin that are very itchy (picture 1)

●Angioedema, which is swelling of the face, eyelids, mouth, tongue, hands, and feet (picture 2)  

●Trouble breathing, wheezing, or a change in your voice

●Throwing up or having diarrhea

●Feeling dizzy or passing out

Allergy shots for insect stings will make you much less likely to get anaphylaxis again if you are stung in the future.

Are allergy shots safe for everyone? — Allergy shots can be safe for people of all ages. If a person gets pregnant while she is getting allergy shots, they can keep getting the shots. But pregnant people should wait until after giving birth to start allergy shots for the first time.

Some medicines, such as beta blockers, can cause problems in people getting allergy shots. Make sure your doctor knows all the medicines you take before starting allergy shots. In some cases, you might need to change your medicines in order to get allergy shots.

What happens when I get an allergy shot? — Most people take an antihistamine before each visit for allergy shots. Common antihistamines include loratadine (sample brand name: Claritin), cetirizine (sample brand name: Zyrtec) and fexofenadine (sample brand name: Allegra).

When you get to the office, the doctor or nurse might ask you for your name and birth date to make sure you get the right shot and not one made for someone else. They will make sure you are healthy enough to get the shot that day. If you have asthma and are having more symptoms than usual, or if you are sick with a fever, you might need to wait and get your shot another day. It is best to call the office before your appointment and check.

You might get just 1 or a few different shots, depending on how many things you are allergic to. After getting the shots, you will need to stay in the office or clinic for 30 minutes to make sure you do not have a serious reaction to the shot.

What can I do to make my shots as safe as possible? — All medical procedures have risks, and allergy shots do, too. But if you follow your doctor's instructions, allergy shots are very safe. Every time you go to get your shots, the following things should happen:

●If you were told to take an antihistamine, your doctor or nurse will make sure you did this.

●Your doctor or nurse will ask you if you had any reactions after your last shot.

●Your doctor or nurse will ask if anything has changed with your health since your last shot. For example, they need to know if you are taking any new medicines, have any new medical problems, or have gotten pregnant. They will also want to know if you are having asthma symptoms or have a fever.

It's important to answer all your doctor or nurse's questions truthfully. Your answers help tell them if you could be at higher risk that day for a serious reaction to the shots.

After you get your shot, you will need to stay in the office or clinic for 30 minutes. This is important because most serious reactions to the shots happen in this time frame.

You should also avoid vigorous exercise for at least a few hours after getting your allergy shots. That's because exercise can make your body absorb the shots faster than it is supposed to. This could put you at risk for an allergic reaction to the shots.

What type of reactions can happen after an allergy shot? — There are 2 types of reactions to allergy shots. The area where the shot was given might turn red, swell, and itch. This is called a local reaction. It can be uncomfortable, but it isn't dangerous.

In rare cases, people get anaphylaxis from an allergy shot. Anaphylaxis caused by allergy shots can be dangerous. It can even cause death if it's not treated right away. If a person gets anaphylaxis, it usually happens within 30 minutes of getting the shots. If this happens in the doctor's office, it can be treated quickly with a shot of a medicine called epinephrine. This is why it is important to stay in the office or clinic for at least 30 minutes every time you get allergy shots. This is also why allergy shots should always be given in a doctor's office and not at home.

How often and how long will I need to get allergy shots? — Most people get allergy shots for 3 to 5 years, although some get them for longer. The first few months, the shots are given 1 to 3 times a week. During this time, the shots get gradually stronger, and allergy symptoms start to improve. After the shots have reached full strength, they are usually given once every 2 to 4 weeks. Symptoms then keep improving over the first few years.

Are there other things I can try besides allergy shots? — There might be. There is a form of treatment that is given as a pill that dissolves under the tongue. This is called "sublingual immunotherapy." This type of treatment doesn't involve getting shots. But it is only available for a few types of allergies.

Sublingual immunotherapy is given every day for several months of the year or year round. The first dose is given in the doctor's office, but after that, it is given at home because it's very safe.

More on this topic

Patient education: Seasonal allergies in adults (The Basics)
Patient education: Insect allergy (The Basics)
Patient education: Anaphylaxis (The Basics)
Patient education: Epinephrine autoinjectors (The Basics)
Patient education: Seasonal allergies in children (The Basics)

Patient education: Allergic rhinitis (Beyond the Basics)
Patient education: Trigger avoidance in allergic rhinitis (Beyond the Basics)
Patient education: Allergic conjunctivitis (Beyond the Basics)
Patient education: Using an epinephrine autoinjector (Beyond the Basics)