by Kassel K
(Desensitization; Hyposensitization; Immunotherapy)

Type of Medication

Flu shot image Allergy shots inject an allergen just under the skin. It may help to decrease your allergy symptoms to that allergen.

What Allergy Shots Are Prescribed For

Allergy shots do not work on all allergies. For example, they are not used to treat food allergies. Shots may be prescribed for:

Still, other treatment options will be tried first. Allergy shots may be considered if:

  • Symptoms are severe
  • Symptoms are difficult to control with medicine or other forms of treatment

How Allergy Shots Work

An allergen is a substance that some are very sensitive to. It will cause allergy symptoms in some. Allergy shots put a small dose of an allergen under your skin. This gives your body time to get used to the allergen. Overtime this decreases the body’s reaction to the allergen. It will decrease or stop symptoms after contact with the allergen.

Many shots will need to be given over time. It can take about 12 months of regular shots before you notice a change. Each shot has a slight increase in the amount of allergen that is given.

Precautions While Using These Medications

Allergy shots are not right for everyone. They are not recommended for people with:

  • Severe asthma that is not controlled with medicine
  • Heart problems
  • Use beta-blocker
  • Age under 5 years

Discuss Pregnancy with Your Doctor

Allergy shots should not be started if you are pregnant. Treatment may or may not be allowed if pregnancy happens after the start of treatment. Discuss your options with your doctor.

Discuss Other Medicine

Tell your doctor if you take or plan to take any medicine. This includes over-the-counter medicine for allergy or other conditions. The allergy shots may affect how other medicine works and affects you.

Continue Other Measures

It will take some time for the allergy shots to work. You may also never reach a full cure. You will need to keep treating your allergies until your doctor says it safe. Use your allergy medicine while you are getting shots.

Dosing Schedule

Allergy shots are given year-round. The schedule may include:

  • Build-up phase—first 3-6 months, you will get 1-2 shots per week
  • Maintenance dose—injected every few weeks to once a month for 3-5 years

After maintenance, you may be able to stop shots completely.

Possible Side Effects

Allergy shots are usually safe. However, it does expose you to an allergen that you react to. There is a risk of an adverse reaction. This may only be as mild such as swelling and redness at the site of the shot. It may remain for 1-3 days. A more serious, life-threatening reaction may also occur. This is called anaphylaxis. Such a reaction is rare.

You will receive your shot in a doctor's office. They will monitor you for at least 20 minutes after the shot. If a bad reaction occurs, the medical personnel will be able to treat you right away.


American College of Asthma, Allergy & Immunology 

Family Doctor—American Academy of Family Physicians 


Allergy Asthma Information Association 

Health Canada 


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Jacobsen L, Niggemann B, Dreborg S, et al. Specific immunotherapy has long-term preventive effect of seasonal and perennial asthma: 10-year follow-up on the PAT study. Allergy. 2007;62(8):943-948.

Pregnancy and allergy. American College of Allergy, Asthma & Immunology website. Available at: Accessed October 25, 2016.

Revision Information