Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use Grastek (Timothy-grass-desensitization).

Allergic Reactions: Some people who take Grastek (Timothy-grass-desensitization) experience a severe allergic reactions. Before you take Timothy grass allergenic extract, inform your doctor about any previous adverse reactions you have had to medications, especially medications used to treat grass allergies. Contact your doctor at once if you experience signs of an allergic reaction, such as skin rash, itching, difficulty breathing or swelling of the face and throat.

Milder allergic reactions such as hives, itching, mouth itchiness, runny nose and throat irritation can occur with the use of Grastek (Timothy-grass-desensitization). If these side effects become bothersome, discuss your concerns with your doctor.

Asthma: Grastek (Timothy-grass-desensitization) may cause asthma symptoms or cause existing asthma symptoms to worsen. If you have a history of asthma, discuss with your doctor how Grastek (Timothy-grass-desensitization) may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Grastek (Timothy-grass-desensitization), and whether any special monitoring is needed. People with uncontrolled asthma should not use Grastek (Timothy-grass-desensitization).

First dose: Severe allergic reactions have occurred with the first dose of Grastek (Timothy-grass-desensitization). For this reason, the first dose should be taken at your doctor's office or a similar location where emergency treatment is available if the medication causes a severe reaction. Your doctor will likely want you to remain in the office for at least 30 minutes after taking the dose, to ensure that it does not cause a severe allergic reaction.

Pregnancy: Grastek (Timothy-grass-desensitization) should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking Grastek (Timothy-grass-desensitization), contact your doctor immediately.

Breast-feeding: It is not known if Timothy grass allergenic extract passes into breast milk. If you are a breast-feeding mother and are taking Grastek (Timothy-grass-desensitization), it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using Grastek (Timothy-grass-desensitization) have not been established for children under 5 years of age. Children should be supervised for at least 30 minutes after taking each dose of Grastek (Timothy-grass-desensitization).