Timothy Grass Pollen Allergen Extract (Sublingual)

Timothy grass pollen allergen extract is an immunotherapy treatment that is used treat the symptoms of grass pollen allergic rhinitis, also known as ‘hay fever'.


Timothy grass pollen allergen extract is an immunotherapy treatment that is used to treat the symptoms of seasonal grass pollen allergic rhinitis, commonly called ‘hay fever'. The treatment is effective in treating the condition whether or not conjunctivitis is present. Allergy to Timothy grass can be confirmed by a skin test that can be carried out by your doctor or an allergen specialist.

The pollen allergen works by desensitising your body to the pollens that trigger your allergic reaction. You should find that allergy symptoms, such as sneezing, itchy, watery eyes, stuffy nose and coughing will be quickly relieved when this medication is taken as directed by your doctor.

In the US, Timothy grass pollen allergen extract is sold under the brand name Grastek. Grastek is available in tablet form and is only available on prescription from your doctor.

Timothy grass pollen allergen extract will not cure your allergy, but it can help to control and manage the symptoms, allowing you to carry on your daily life without the bothersome side effects of the allergy.

Conditions treated

Type of medicine

  • Immunotherapy
  • Tablet

Side effects

Together with its desired effects, some medication can cause some unpleasant side effects. You might not notice any side effects, but if you do find that you are suffering from bothersome side effects, you may need to seek medical attention. Consult your doctor immediately if you notice any of the following effects when taking Timothy grass pollen allergen extract.

You may find that you develop an itching sensation in your mouth, on your tongue, or in your ears. In addition, you may experience a tingling feeling or numbness around your mouth. You may have some swelling in or around your mouth and your throat may become sore.

Less commonly, but still experienced by some patients, are side effects that involve problems with breathing and chest discomfort. In addition to this, you may have difficulty swallowing, your lips may become swollen and you could find that you develop a rash, welts, or hives on your skin. You may feel tightening in your chest and you could also develop a runny nose.

Some rarely reported side effects suffered by people taking Timothy grass pollen allergen extract include dizziness, lightheadedness or fainting, especially when standing quickly from a seated position or from lying down. Feeling unusually tired or weak has also been reported, as well as a fast heartbeat and unexplained sweating.

If you experience any of the aforementioned side effects, you should consult your doctor for advice.

There are a number of side effects that resolve themselves naturally as your body acclimatizes to the new medication. Your doctor may be able to suggest ways of overcoming these effects or preventing them from occurring. If you find that any of these effects do not sort themselves out within a week or two of commencing treatment with Timothy grass pollen allergen extract tablets or become particularly bothersome, check with your healthcare professional.

During the course of their treatment with Timothy grass pollen allergen extract, some people complain of diarrhea, nausea, heartburn, headaches, sour or acid stomach, a dry throat, excessive drowsiness.

The list of effects mentioned above is not all inclusive, and you should be aware that there are other side effects that may occur in some patients. If you notice that you are suffering from any other unusual or unpleasant effects that you did not have prior to commencing treatment with the medication, have a chat with your doctor.


You should take Timothy grass pollen allergen extract exactly as prescribed and as directed by your treating physician. Do not take extra or more frequent doses, and do not take it for longer than your doctor has directed you to. You should receive a Medication Guide with this medication, so be sure to read and follow the instructions given in the Guide, and always ask your doctor if you have any questions.

You should begin taking the medication at least three months prior to the onset of the grass pollen season. Continue taking Timothy grass pollen allergen extract for the duration of the grass pollen season. The medication should be taken daily for at least three years in order to provide a sustained effect for the fourth year, during which time you will not have to take the medication.

When taking your first dose of Timothy grass pollen allergen extract, you should do so in a clinic or hospital where you can be monitored for at least 30 minutes afterwards for any signs of a severe allergic reaction. If the first dose of the medication does not cause any issues, you may continue to take subsequent doses at home.

Wash and dry your hands thoroughly before and after taking the medication. Be sure that your hands are completely dry before removing each tablet from its blister pack. Place the tablet underneath your tongue and allow it to dissolve for a minute or so before swallowing.

Do not eat or drink anything for about five minutes after you have taken the tablet.

You should follow your doctor's instructions or the directions on the product label when taking this medication. The dose will vary between patients and the following information indicates the average dose only. If your prescribed dose is different, do not alter it unless your prescribing physician instructs you to do so.

The size of the dose you prescribed will depend on the strength of the medicine. The number of doses that you will take each day, the time you should leave between each dose and the duration of the course of the medication will depend on the specific medical reason for which you are prescribed the medication.

Adults up to 65 years of age: one tablet (2800 bioequivalent allergy units BAU) per day.

Children five years of age and over: one tablet (2800 bioequivalent allergy units BAU) per day.

Adults over 65 years and children under five years of age should take the medication as directed by their doctor.

If you miss a dose of your medication, omit the missed dose and revert to your usual dosing schedule. Do not double dose. If you omit more than one dose of the medicine, ask your doctor for further instructions.

Drug interactions

Drug interactions can alter the way in which your medications work and can increase the risk of you suffering serious side effects. Before you begin taking this medication, mention to your doctor any drugs that you already use, including both prescription and over the counter medication, vitamin supplements and herbal preparations.

Do not stop, start or alter the dose of any of the medications that you are taking without the prior approval of your doctor.

There are not currently any noted major drug interactions recorded for Timothy grass pollen allergen extract.


You should make regular visits to see your doctor for check ups while you or your child are taking this medication. These visits provide your doctor with the opportunity to see if the medication is working correctly and to decide if it is best for you to keep taking it.

In some people, the medication can cause serious side effects or allergic reactions, including anaphylaxis. Anaphylaxis is a very serious condition that requires immediate urgent medical attention. Symptoms of anaphylactic shock include irregular or very fast breathing, struggling for breath, wheezing, and losing consciousness. The colour of the skin on the face may change, the patient's heartbeat may become extremely irregular or elevated, and swelling may appear around the eyelids or the eyes. If any of these side effects appear, you should summon emergency medical assistance at once.

Your doctor may recommend that you carry an emergency injection in case of severe allergic reactions to this medication throughout the duration of your course. Make sure that you understand how to administer the injection and that your child's teacher or carer has a supply and knows how to use it.

Timothy grass pollen allergen extract can increase your risk of eosinophilic esophagitis. If you or your child suffer from severe chest pains or have trouble swallowing during the course of treatment with this medication, check with your doctor right away. This medication can also cause a bad reaction in asthma sufferers. If you or your child experience breathing difficulties, you should call your doctor immediately.

Timothy grass pollen allergen extract can cause problems in people who suffer from the following existing medical conditions:

  • asthma
  • chronic obstructive pulmonary disease (COPD)
  • heart problems, including angina, history of heart attack or irregular heartbeat
  • high blood pressure
  • cold sores
  • eosinophilic esophagitis

You should also tell your doctor if you have already had allergy shots or if you are currently taking any other allergy treatments.

Before you have any form of surgery or undergo dental treatment, be sure to tell your doctor or dentist about all other medication that you are using. This includes over the counter medication and herbal products, as well as prescription drugs. You may be advised by your doctor or dentist to stop taking this medication following surgery or a dental procedure, such as a tooth extraction.

Before using this medication during pregnancy, you should discuss the risks and benefits with your doctor. It is not known if this medication poses a risk to breastfeeding babies. Ask your doctor's advice if you are already breastfeeding or if you are planning to do so during the course of your treatment.


Always keep your seasonal allergy medication in a sealed, airtight container and at room temperature. Do not freeze the medication or expose it to radiators, fires or other heat sources. Do not leave the medication where it could be exposed to direct sunlight and keep the medication dry.

Keep the medication out of reach of children and pets. In the event that a pet consumes the medicine, seek veterinary advice immediately.

Never use medication that has passed its use-by date or if the packaging is open or damaged. Ask your doctor or pharmacist for directions on how to dispose of your old or unused medication.


Timothy grass pollen allergen extract is an immunotherapy treatment that is used to treat the symptoms of seasonal grass pollen allergic rhinitis, commonly called ‘hay fever'. This medication will also tackle conjunctivitis in cases where it is apparent.

Although this medication does not have any serious drug interactions for patients to be aware of, it should not be used if you suffer from chronic obstructive pulmonary disease (COPD), asthma, high blood pressure, cold sores, angina, eosinophilic esophagitis, or if you have a history of heart disease or heart attack. The medication is safe for use in adults and in children over five years of age.

The medication helps to dampen down the effects of seasonal pollens on the body, thus alleviating the symptoms and improving a sufferer's tolerance to pollens during the allergy season. This can mean that the more serious debilitating effects of seasonal allergies are removed, relieving the misery the allergy causes to the sufferer and allowing them to enjoy their daily lives without having to endure unpleasant side effects.

To achieve the best results, it is important that you work closely with your doctor to find the appropriate dose and frequency of use for this medication. You may also be recommended to have a skin test to determine how effective this medication will be in treating your seasonal pollen allergy.

Last Reviewed:
December 25, 2017
Last Updated:
April 05, 2018
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