When you should consider allergy shots and what to expect during immunotherapy

• Allergy shots may be worth considering if your allergy symptoms are severely impacting your life.
• Typically, allergy shots are for seasonal allergies to pollen, animal dander, dust, mold, and more.
• Allergy shots can offer long-term relief but they also require a commitment over multiple years.

Allergy shots, also known as immunotherapy, are a series of injections that can decrease your sensitivity to allergies and reduce the severity and frequency of symptoms.

They work by exposing your body to a low dose of the allergen, whether it's pollen or insect stings. Over time, this helps you build a tolerance for it, so you no longer react as severely.

Allergy shots can be a very effective form of treatment, but it's not necessary for many people. Here's what you need to know about the risks and benefits of allergy shots, and whether it's right for you.

Who needs allergy shots?

Allergy shots are rarely the first recommended treatment for allergies. Often, your doctor will advise you to avoid allergy triggers, try a nasal saline rinse, and use medication like antihistamines or decongestants.

However, if those treatments aren't effective, allergy shots may be another option. Overall, you could be a good candidate for allergy shots if:

• Your allergy symptoms are not well managed with over-the-counter or prescription allergy medicine.
• You experience harmful side effects from allergy medicine.
• Your allergy symptoms are a major disruption to your life. For example, your symptoms contribute to nasal polyps or frequent sinus and ear infections.
• You develop asthma attacks when exposed to allergens.
• You've experienced a severe allergic reaction, known as anaphylaxis, which can be life-threatening.

Allergy shots are mainly used to treat environmental and seasonal allergies, which are typically caused by pollen, animal dander, dust, or mold. They can also lessen the severity of allergic reactions to insect stings.

However, they are not recommended for food allergies because there is a greater risk of severe side effects.

Benefits of allergy shots

Allergy shots can be effective at reducing allergy symptoms - especially for seasonal allergies and allergies to dogs and cats.

For example, a 2016 study published in Annals of Allergy, Asthma and Immunology examined two groups of 65 to 75-year-olds with hay fever triggered by pollen and grass allergies. One group was given allergy shots, while the other received a placebo over the course of three years.

The allergy shot group reported a 55 percent reduction in symptoms of hay fever, like sneezing and itchy eyes, and a reduction of 64 percent in the amount of allergy medication needed for relief.

It can take about six months to a year of allergy shots for someone to notice a change in allergy symptoms, and about two to three years for the treatment to reach its full effect.

"For some people, it offers significant improvement, and for others, it provides partial improvement or at least lets them decrease their medications and feel more comfortable in general," says Omid Mehdizadeh, MD, otolaryngologist and laryngologist at Providence Saint John's Health Center.

Overall, immunotherapy treatment typically spans three to five years, though some people may receive allergy shots for shorter or longer periods of time, depending on how well they respond to the treatment.

Risks of allergy shots

Allergy shots can come with mild side effects including:

• Redness and swelling at the injection site
• Itching
• Rash
• Fever
• Sneezing
• Watery eyes
• Nasal congestion

These side effects are not life-threatening and will usually resolve on their own.

However, a severe allergic reaction known as anaphylaxis can be a more dangerous side effect of allergy shots. Anaphylactic reactions from allergy shots are rare, occurring in fewer than one out of 1,000 people.

Allergy symptoms, like sneezing and itchy eyes, are your immune system's response to a sensitive trigger, like pollen or an insect sting. Anaphylaxis is an extreme version of that immune response, causing your airways to narrow and your blood pressure to drop.

Symptoms of anaphylaxis include:

• Hives or itchy skin
• Dizziness
• Chest tightness
• Nausea
• Wheezing or difficulty breathing
• Swelling of the lips, tongue or throat

Usually, an anaphylactic reaction will only occur within five to 30 minutes of allergen exposure. Because of this, allergy shots are typically administered in a doctor's office and the person receiving the injection is monitored for half an hour. If someone does have an anaphylactic reaction to an injection, they are likely to discontinue immunotherapy.

People with a history of asthma or who have experienced an anaphylactic reaction before are at greater risk of experiencing one after an allergy shot, Mehdizadeh says. Some patients are given an allergy medication, like an antihistamine, before the injection to help prevent a severe reaction.

Doctors recommend people who are receiving immunotherapy keep an epi-pen with them at all times to administer epinephrine should they have a severe reaction, Mehdizadeh says.

How to get allergy shots

If you're struggling to manage your allergy symptoms, you should consult with an otolaryngologist, allergist, immunologist, or an ear, nose, and throat (ENT) doctor.

After evaluating your symptoms and reviewing your medical history, you will undergo an allergy test before starting immunotherapy.

The shots are most successful when they are tailored to an individual, Mehdizadeh says, and an allergy test helps your doctor determine exactly what you are allergic to.

Here's what happens during immunotherapy:

1. You'll receive an allergy skin test. The doctor will inject a small dose of an allergen into the skin, either on your arm or back, and then observe your skin for an allergic reaction. Swelling or redness tells the doctor you are allergic to that substance. The results of this test will help your doctor determine which allergens to include in your injections.

2. You'll begin to receive allergy shots. Injections are administered on a schedule over the course of about three to five years, Mehdizadeh says. During the first year you'll likely receive them in a doctor's office once a week and stay for half an hour afterward to make sure you don't have a severe reaction.

3. In the second year, you'll likely receive allergy shots every two to three weeks and the allergen dosage will gradually increase. The shots will still be administered in the office and you'll continue to be monitored.

4. In the third year, you'll receive allergy shots once a month. If you've done well with the treatment, you'll transition to maintenance therapy, meaning the allergen dosage will no longer increase. Some providers may allow you to do the maintenance shots at home if you've done well on the treatment and haven't had a severe reaction, Mehdizadeh says.

Insider's takeaway

Allergy shots can provide long-term relief from symptoms for many years, Mehdizadeh says, but allergies can also change over time - and you may notice additional or new symptoms years after completing immunotherapy.

There's also a chance you could develop further symptoms if you move to a new environment and are exposed to different allergens. After immunotherapy, if your allergy symptoms persist or you develop new ones, it's worth discussing with your doctor.

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