Timothy Grass Pollen Allergen Extract

Timothy Grass Pollen Allergen Extract

Why is it prescribed?

It is an under-the-tongue immunotherapy to treat Timothy and related grass pollen allergies that can cause sneezing, runny or itchy nose, stuffy or congested nose, or itchy and watery eyes. It can be prescribed for people 5 through 65 years of age who are allergic to grass pollen.

Products that have this ingredient include •Grastek® sublingual tablets •

See other drugs used in the treatment of •allergic rhinitis •allergies •hay fever •seasonal allergies •seasonal rhinitis •

The most commonly reported side effects are itching of the mouth, lips, or tongue, swelling under the tongue or throat irritation.


The immune system is the target of immunotherapy. The aim is to prevent or suppress allergic symptoms, such as allergic rhinitis, through repeated administration of the allergen. The effect of sublingual immunotherapy is thought to be mediated through local and systemic immunomodulatory mechanisms (immune deviation) including changes in allergen specific antibodies and regulatory T- cells leading to long-term tolerance development.


Do not use if you have severe, unstable or uncontrolled asthma. It can cause severe allergic reactions that may be life-threatening. Stop taking and get medical treatment right away if you have any of the following symptoms:

  • trouble breathing
  • throat tightness or swelling
  • trouble swallowing or speaking
  • dizziness or fainting
  • rapid or weak heartbeat
  • severe stomach cramps or pain, vomiting, or diarrhea
  • severe flushing or itching of the skin


Do not use if you have had difficulty with breathing due to swelling of the throat or upper airway after using any sublingual immunotherapy before or if you have been diagnosed with eosinophilic esophagitis.
This is NOT a medication that gives immediate relief from symptoms of grass allergy.
You should have auto-injectable epinephrine available to inject in case of a severe allergic reaction to this medication.

The first tablet must be taken at the physician's office under medical supervision and the patient must be monitored for at least 30 minutes.

Each dose given to a child must be given under direct adult supervision for at least 30 minutes.

Your doctor may decide that this is not the best treatment for you if you have COPD, coronary artery disease, an irregular heart rhythm or high blood pressure that is not well controlled.

Drug interactions:

Certain medications may enhance the likelihood of a severe reaction with grass pollen extract or interfere with the treatment of a severe reaction. These include:

  • beta blockers and alpha- blockers
  • digoxin
  • diuretics (water pills)
  • MAOI's or tricyclic antidepressants
  • thyroid hormones


Stop taking this medication if you develop mouth infections, ulcers or cuts in the mouth or throat.

Use in pregnancy: No clinical data are available for use during pregnancy. Do not start use during pregnancy because of the risk of severe systemic reactions which may be harmful to the mother or fetus.

Use in breastfeeding:  It is not known if this medication appears in breast milk.  Consult with doctor or pharmacist before use.