What Are Allergy Shots?

Allergen immunotherapy exposes patients to a tiny amount of an allergen, which can help build immunity and get you closer to long-lasting relief.

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Whether they're seasonal or year-round, allergies can put a serious damper on a person's quality of life.

But for certain types of allergies, allergen immunotherapy (commonly known as allergy shots) can be a big help. Allergy shots work by exposing patients to tiny amounts of whatever it is they're allergic to. The amount of allergen in each injection increases gradually over time so the body can build up a tolerance.

They may require a lot of time and effort, but the benefits of allergy shots can be life-changing and long-lasting for people of all ages.

"Everyone is different, and it's true that some people don't have a good response," Laura Dziadzio, MD, a pediatric allergist with Asthma and Allergy Center-Lynchburg, told Health. "But for others, it's like night and day. I have lots of patients who were really miserable and are now doing much better and can finally enjoy the things they couldn't before."

Here's what you should know about allergy immunotherapy treatments if you are considering using them.

How To Prepare for Allergy Shots

If allergen immunotherapy is something you may be interested in, talk with an allergist to see the treatment plan most appropriate for your case. It's also important to know the exact triggers for your allergies before getting allergy shots.

An allergist can help confirm which allergens give you problems. The provider may use skin testing or blood tests to determine your allergy triggers. The confirmed allergens, except for food allergens, will be the only ones included in your allergy shots.

Who Should—And Who Shouldn't—Get Allergy Shots?

Allergy shots are recommended for some individuals but not all of them. Talk to a healthcare provider to understand if this is a good treatment option for your allergies.

People Eligible for Allergy Shots

Allergy shots can be effective for people with seasonal allergies. Still, they can also work for year-round indoor allergies—like mold, dust mites, and animal dander—and allergies to insect bites or stings.

Getting allergy shots for insect-related allergies may be beneficial. "In the case of stinging insects, the shots can be close to curative," said Dr. Dziadzio. "That's the one time I really push people to get the shots no matter what because it's such a dangerous allergy."

Allergy shots may also be a good choice for people who can't avoid things they're allergic to—like a pet or the great outdoors. Healthcare providers will still recommend oral histamines, nasal steroids, and traditional therapies along with allergy shots.

People Not Eligible for Allergy Shots

If you have a food allergy, allergy shots are not an option. Instead, the best course of action is to avoid being around the trigger food or foods.

Most adults and children—so long as they can communicate symptoms of an allergic reaction—can get allergy shots. But if you or your child has severe, uncontrolled asthma, a healthcare provider may recommend against them until the asthma symptoms are well controlled.

"In our practice, if a patient's asthma is flaring or even if they're sick, we generally wait to give the shot until they're feeling better," said Dr. Dziadzio.

People who become pregnant while in the maintenance phase of allergy shots can continue their treatment. But they shouldn't start allergy shots for the first time, or increase allergy shot doses, while pregnant.

Those individuals with heart-related conditions, such as having had a recent heart attack, are also not good candidates for allergy shots. This is because allergy immunotherapy increases their risk of death in case of an allergic reaction to the immunotherapy injection.

Certain medicines, like beta-blockers or angiotensin-converting enzyme (ACE) inhibitors, can reduce the effectiveness of epinephrine—the lifesaving drug used to treat anaphylactic shock.

However, other medications like glucagon can be used in conjunction with epinephrine to reverse the effects of beta-blocker medications.

Anaphylaxis is when the body has an extreme immune system response (e.g., lowered blood pressure, airway blockage) to something foreign. Because anaphylaxis is a rare but serious risk for people getting allergy shots, allergy shots may not be recommended for people who take beta-blockers or ACE inhibitors.

So you'll want to talk with an allergist about whether you're a candidate for allergy shots.

More About Beta-Blockers and ACE Inhibitors

Beta-blockers and ACE inhibitors are both blood pressure medications. Beta-blockers lower blood pressure by decreasing how hard the heart works, a person's heart rate, and the amount of blood the heart puts out. ACE inhibitors lower blood pressure by helping blood vessels open up more.

Allergy Shots Time Commitment

Allergy shots are given in two phases. In the "build-up" phase, you'll need a shot once or twice a week for about three to six months. After that, you'll enter the "maintenance" phase and receive them less often—about once or twice a month for several years.

Sticking to this schedule is important—for the shots' effectiveness and to reduce your chances of having a bad reaction. "For some people, it's absolutely worth it, but some people just don't have that time to spare," said Dr. Dziadzio.

And while the shots themselves don't take long to get, it's recommended that you wait for 30 minutes in the allergist's office after each one in case of any reactions.

Potential Benefits of Allergy Shots

Getting allergy shots can have advantages. You may find relief for your allergies or other health conditions.

Different Types of Relief from Allergies

Allergy shots may help you get relief in the long term. "It changes the person's immune system from having a bad reaction to pretty much ignoring the allergen," said Dr. Dziadzio. "For some people, it decreases their allergies enough so they can come off medicine entirely, and for some, it helps their medicines be more effective."

Possible Improvement With Other Health Conditions

When people think of allergy symptoms, they generally think of itchy eyes, a stuffy nose, or a runny nose. And while allergy shots can help prevent all of those, they can also help with related conditions.

If you have asthma, getting your allergies under control may also help reduce flare-ups, improve your breathing, and reduce your need for medications. Eczema, an inflammatory skin condition, is often associated with (and can be made worse by) environmental allergies.

Changes in Physical and Mental Health

Additionally, allergies have the capacity to affect a person's quality of life, which could include aspects of physical and mental health.

Researchers found that, over their lifetime, people with seasonal allergies would be more likely to report having:

  • Mood disorders
  • Anxiety disorders
  • Eating disorders

If severe allergies have taken a toll on your health and happiness, your mental state may also improve with the help of allergy shots or other immunotherapy options.

For example, research has noted that studies have shown the positive effect that allergen immunotherapy can have on the quality of life of those with grass pollen allergies.

Potential Risks and Side Effects

Just as there are benefits to getting allergy shots, there are also risks. Talk to a healthcare provider if you are concerned about starting allergy shots.

Relief Isn't a Fast Process

Allergy shots aren't a quick fix. While some people may start to feel better during the build-up phase of their treatment, most people won't experience noticeable improvement until they've been in the maintenance phase for six to 18 months, said Dr. Dziadzio.

One study found that it took three full years for allergy shots for hay fever to be more effective than placebo shots.

The maintenance phase for most allergy shots is usually continued for three to five years. Some patients experience long-lasting relief after that, and some may need continued treatment.

Allergic Reactions Can Happen

Because allergens are involved, reactions to the shots themselves are possible. These can range from swelling and itching at the injection site (usually the arm) to sneezing and a runny nose to anaphylactic shock in rare cases.

That's why it's recommended that patients stay at the provider's office after each shot—no matter how long they've been on allergy shots—so they can be monitored and treated for reactions if they do occur.

What Can Help You When You Get Allergy Shots?

Taking an oral antihistamine (like Zyrtec, Allegra, or Claritin) before each shot can help reduce side effects and reactions—particularly where your shot is given.

"We really encourage patients to take them beforehand, especially as they get closer to their maintenance dose, and their local reactions [on their arms] can get pretty bad," said Dr. Dziadzio.

Taking an antihistamine can help prevent most reactions but not all. Completing pretreatment with antihistamines won't stop a person from potentially experiencing anaphylaxis.

Other Options Beyond Allergy Shots

For people who hate shots or can't keep up with an allergy shot schedule, sublingual (under the tongue) therapy—known as SLIT—may be another option. This immunotherapy is delivered in daily tablets that dissolve under the tongue.

There are different SLIT options available based on allergen type. Approved sublingual therapies are on the market for:

  • Grass pollen (Oralair, for individuals aged 10 to 65)
  • Short ragweed pollen (Ragwitek, for individuals aged 5 to 65)
  • Timothy grass pollen (Grastek, for individuals aged 5 to 65)
  • Dust mites (Odactra, for individuals aged 18 to 65)

Some allergy practices will also administer liquid drops under the tongue to treat other types of allergies, although these treatments are not FDA-approved.

A Quick Review

Allergen immunotherapy, or allergy shots, is a long-term option to get relief from most types of environmental allergies. Allergy shots are not recommended for everyone, and they come with benefits (e.g., symptom relief) and risks (e.g., allergic reactions).

Other allergen immunotherapy options are available, like tablets, if allergy shots may not work for you. Additionally, the shots don't take long to administer; however, the time required to see improvement in your allergy symptoms can take months or years.

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