Grastek

Generic name: timothy grass pollen allergen extract [ TIM-oh-thee-grass-PAW-len-AL-er-gen-EX-tract ]
Drug class: Allergenics

Medically reviewed by Drugs.com on Jun 14, 2023. Written by Cerner Multum.

What is Grastek?

Grastek is made from certain pollens that can cause seasonal allergies (hay fever).

Grastek is used to help your body develop an immunity to certain pollens that can cause allergy symptoms such as sneezing, itching, and watery eyes. Grastek is for use in adults up to age 65, and children who are at least 5 years old.

This medicine will not provide immediate relief from allergy symptoms.

Grastek may also be used for purposes not listed in this medication guide.

Grastek side effects

Grastek may cause a severe allergic reaction. Stop taking the medicine and get emergency medical help if you have any of these signs of an allergic reaction:

• severe dizziness or a light-headed feeling (like you might pass out);

• fast heart rate;

• stomach pain, vomiting, diarrhea;

• hives, itching, flushing (warmth, redness, or tingly feeling);

• cough, chest tightness, wheezing, trouble breathing; or

• swelling of your face, lips, tongue, or throat.

If you stop taking Grastek after having an allergic reaction, do not start taking the medicine again without your doctor's advice.

Grastek may cause serious side effects. Call your doctor at once if you have:

• severe mouth or throat irritation;

• breathing problems; or

• choking feeling, chest pain, trouble swallowing.

Common side effects of Grastek may include:

• swelling or itching of your mouth or tongue;

• throat irritation; or

• itching in your ears.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Warnings

You should not use Grastek if you have uncontrolled asthma, or if you have a history of allergic reaction to a pollen-extract medicine, or allergic reaction that affected your esophagus.

You may not be able to use Grastek if you have certain medical conditions, such as breathing problems, heart disease, or high blood pressure. This medicine also may not be safe for you if you take certain medicines.

Grastek may cause a severe allergic reaction. Your doctor will give you the first dose and watch you closely to make sure you do not have a reaction.

Your doctor may also prescribe epinephrine (Epi-Pen) to keep with you in case you ever have an allergic reaction to Grastek.

Stop taking this medicine and get emergency medical help if you have signs of an allergic reaction: severe dizziness, feeling like you might pass out; fast heart rate, cough, chest tightness, wheezing, trouble breathing; stomach pain, vomiting, diarrhea; hives, itching, flushing (warmth, redness, or tingly feeling); swelling of your face, lips, tongue, or throat.

Before taking this medicine

You should not use Grastek if you have ever had an allergic reaction to similar pollen-extract medicines, or if you have:

• severe or uncontrolled asthma; or

• a history of allergic reaction that affected your esophagus (the tube that connects your mouth and stomach) and caused heartburn or trouble swallowing.

To make sure Grastek is safe for you, tell your doctor if you have:

• breathing problems;

• heart disease;

• uncontrolled high blood pressure;

• mouth sores, swollen gums, or other wounds or irritations inside your mouth;

• if you take an antidepressant or migraine headache medicine; or

• if you take medicine to treat heart problems, high blood pressure, or a prostate disorder.

FDA pregnancy category B. Grastek is not expected to harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant during treatment.

It is not known whether timothy grass pollen allergen extract passes into breast milk or if it could harm a nursing baby. Tell your doctor if you are breast-feeding a baby.

Grastek should not be given to a child younger than 5 years old.

This medicine is not for use in people older than 65.

How should I take Grastek?

Your doctor may perform an allergy skin test or blood test to make sure you are allergic to the specific pollen contained in Grastek.

Follow all directions on your prescription label. Do not take this medicine in larger or smaller amounts or for longer than recommended.

Your doctor may want to give your first dose of this medicine in a clinic setting. You should be watched closely for at least 30 minutes after taking your first dose, to make sure you do not have an allergic reaction.

Grastek is a sublingual tablet that dissolves under your tongue. Do not chew this tablet or swallow it whole.

To take the sublingual tablet:

• Keep the tablet in its blister pack until you are ready to take it. Open the package and peel back the foil.

• Use dry hands to remove the tablet and place it in your mouth.

• Place the sublingual tablet under your tongue and allow it to dissolve completely.

• Do not swallow for at least 1 minute. Do not eat or drink anything for at least 5 minutes.

Wash your hands after handling the sublingual tablet.

A child using timothy grass pollen extract should be supervised by an adult while taking this medicine.

Grastek is usually taken once daily throughout allergy season. For best results, start taking this medicine at least 12 weeks before the start of allergy season.

In some cases, you may need to take Grastek every day all year long, for up to 3 years. Follow your doctor's dosing instructions very carefully.

Your doctor may also prescribe epinephrine (Epi-Pen) to keep with you in case you ever have an allergic reaction to Grastek.

If you need oral surgery or dental work, or if you have a mouth injury or infection, you may need to stop using this medicine until your mouth heals. Tell your doctor if the sublingual tablets cause any mouth irritation.

Store tablets in the blister pack at room temperature, away from moisture and heat.

What happens if I miss a dose?

Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What should I avoid while taking Grastek?

Ask your doctor before starting any new medicine or treatments, including allergy shots.

What other drugs will affect Grastek?

Other drugs may interact with timothy grass pollen allergen extract, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell each of your health care providers about all medicines you use now and any medicine you start or stop using.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Medical Disclaimer

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