Diluted extracts of the pollen are injected under the patient's skin. The patient receives small doses once or twice a week, working up to larger doses that are given less often. The size of the largest dose depends on the patient's tolerance and the treatment's effect on the patient's allergy symptoms. Since it takes time to build up tolerance, prolonged treatment (3-5 years) may be needed before the patient's symptoms are relieved.

Sub Cutaneous (SCIT) Immunotherapy is not without problems. It can be expensive, and may require months before improvement is apparent. Further, it does not work well for some people and, if the size of the dose or frequency of shots is not carefully monitored, the injections can cause allergic reactions. These reactions can be quite mild - redness and swelling at the site of the injection - or potentially serious systemic reactions such as hives, generalized swelling, or shock. Immunotherapy is therefore only one part of a physician's overall treatment plan for an allergic patient.