Allergy Shots: 9 Facts To Know About Them

They Contain Allergens, So Reactions Can Happen

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.

"It changes the person's immune system from having a bad reaction to pretty much ignoring the allergen," Dr. Dziadzio said. "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."

But 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, in rare cases, anaphylactic shock, which is severe and could be life-threatening. That's why it's recommended that patients stay at their healthcare provider's office for 30 minutes after each shot so they can be monitored and treated for reactions if they do occur, according to MedlinePlus.

They're Not Just for Seasonal Allergies

Allergy shots can be effective for people with hay fever and other seasonal allergies, but they can also work for year-round indoor allergies—like mold, dust mites, and animal dander—and allergies to insect bites or stings. Unfortunately, they don't seem to work for food allergies.

"In the case of stinging insects, the shots can be close to curative," Dr. Dziadzio said. "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 don't like taking medications or can't (or don't want to) avoid the thing they're allergic to—like a pet or the great outdoors.

They're a Big 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, according to the American Academy of Allergy, Asthma & Immunology (AAAAI),

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," Dr. Dziadzio said. And while the shots themselves only take a minute, you probably will have to wait those 30 minutes in your healthcare provider's office after each one.

Antihistamines Can Make Allergy Shots Easier

Taking an oral antihistamine (like Benadryl or Claritin) before each shot can help reduce side effects and reactions. "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," Dr. Dziadzio said.

Of note, taking an antihistamine can help prevent most reactions but not all. MedlinePlus indicated that completing pretreatment with antihistamines "does not prevent anaphylaxis," when the body has an extreme immune system response (e.g., lowered blood pressure, airway blockage) to something foreign.

They Can Take a Few Years To Really Work

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, Dr. Dziadzio said.

In fact, a February 2017 JAMA 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.

They're not recommended for everyone

Most adults—and children ages five and up—can get allergy shots. But if you or your child has severe, uncontrolled asthma, your healthcare provider may recommend against them. "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," Dr. Dziadzio said.

Women who become pregnant while in the maintenance phase of allergy shots can continue their treatment, according to the AAAAI. But women shouldn't start allergy shots for the first time, or increase their dosage, while pregnant.

Certain medicines, like beta blockers, can reduce the effectiveness of epinephrine—the lifesaving drug used to treat anaphylactic shock. Because anaphylaxis is a rare but serious risk for people getting allergy shots, they may not be recommended for people who take these drugs.

They Can Make Asthma and Eczema Better

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

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.

They Could Improve Mental Health

Allergies have the capacity to affect a person's quality of life, which could include aspects of physical and mental health, according to a January 2016 Drug Discovery Today article

Further, researchers of a September 2018 study published in the International Journal of Environmental Research and Public Health found that "a history of seasonal allergies was associated with significantly higher odds of reporting lifetime mood disorders, anxiety disorders, and eating disorders."

However, the January 2016 Drug Discovery Today article noted that studies have shown the positive affect that allergen immunotherapy can have on the quality of life for those with grass pollen allergies.

Therefore, if severe allergies have really taken a toll on your health and happiness, it's possible that mental state can improve as well with the help of allergy shots or other immunotherapy options.

A Shot Isn't Your Only Option

For people who hate shots or can't keep up with their intensive schedule, sublingual (under the tongue) therapy—known as SLIT—may be another option, according to the AAAAI. This type of immunotherapy is delivered in daily tablets that dissolve under the tongue, and only the first few doses need to be taken with a healthcare provider present.

Per the AAAAI, 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)

Additionally, Palforzia is the only FDA-approved oral treatment (in powder form) available for children aged 4 to 17 with peanut allergies.

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

If allergen immunotherapy is something you may be interested in, be sure to talk with your healthcare provider to see what treatment plan is most appropriate for your individual case.