Telfast are used to relieve or prevent the symptoms of hay fever and other types of allergy. They work by preventing the effects of a substance called histamine, which is produced by the body. Histamine can cause itching, runny nose, sneezing, and watery eyes. Also, in some persons histamine can close up the bronchial tubes (air passages of the lungs) and make breathing difficult.

Some of the antihistamines are also used to prevent motion sickness, vomiting, nausea, and dizziness. In patients with Parkinson's disease, diphenhydramine may be used to decrease stiffness and tremors. Also, the syrup form of diphenhydramine is used to relieve the cough due to colds or hay fever. In addition, since antihistamines may cause drowsiness as a side effect, some of them may be used to help people go to sleep.

Telfast is also used in the treatment of chronic urticaria, which is a persistent hive-like rash.

Antihistamines may also be used for other conditions as determined by your doctor.

Some antihistamine preparations are available only with your doctor's prescription. Others are available without a prescription. However, your doctor may have special instructions on the proper dose of the medicine for your medical condition.

Special precautions

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For antihistamines, the following should be considered:

Allergies— tell your doctor if you have ever had any unusual or allergic reaction to Telfast . Also tell your health care professional if you are allergic to any other substances, such as preservatives, foods, or dyes.

Diet— Make certain your health care professional knows if you are on a low-sodium, low-sugar, or any other special diet. Most medicines contain more than their active ingredient, and many liquid medicines contain alcohol.

Pregnancy— Telfast is not recommended for use in the first months of pregnancy since it has been shown to cause birth defects in animal studies when given in doses many times higher than the usual human dose. Be sure you have discussed this with your doctor.

Breast-feeding— Small amounts of Telfast pass into the breast milk. Use is not recommended since babies are more susceptible to the side effects of antihistamines, such as unusual excitement or irritability. Also, since these medicines tend to decrease the secretions of the body, it is possible that the flow of breast milk may be reduced in some patients. It is not known yet whether cetirizine, desloratadine, or loratadine cause these same side effects.

Children— Serious side effects, such as convulsions (seizures), are more likely to occur in younger patients and would be of greater risk to infants than to older children or adults. In general, children are more sensitive to the effects of Telfast . Also, restlessness, nervousness, nightmares or unusual excitement, or irritability may be more likely to occur in children.

Older adults— Elderly patients are usually more sensitive to the effects of Telfast . Confusion; feeling faint; drowsiness; dizziness; difficult or painful urination; or dryness of mouth, nose, or throat may be more likely to occur in elderly patients. Also, restlessness, nervousness, nightmares or unusual excitement, or irritability may be more likely to occur in elderly patients.

• Other medicines— although certain medicines should not be used together at all, in other cases different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary.

Other medical problems— the presence of other medical problems may affect the use of antihistamines. Make sure you tell your doctor if you have any other medical problems, especially:

• Kidney disease—Effects of desloratadine may be increased because of slower removal from the body.
• Liver disease or
• Stomach ulcer—Use of cyproheptadine may make these conditions worse.
• Intestinal obstruction or
• Glaucoma—These medicines may cause a slight increase in inner eye pressure that may make the condition worse
• Urinary tract blockage or difficult urination— Telfast may make urinary problems worse
• Enlarged prostate or

Side effects

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if the following side effect occurs:

• Less common or rare

Less frequent or rare with azatadine, diphenhydramine, dexchlorpheniramine, desloratadine, cyproheptadine, clemastine, cetirizine, or loratadine

• Fast or irregular heartbeat; unusual tiredness or weakness; tingling; tightness in chest; swelling; skin rash; shortness of breath; seizures ; redness of skin; puffiness or swelling of the eyelids or around the eyes, face, lips or tongue ; prickly sensations; itching; hives; headache; fever; fast heartbeat; dizziness; difficulty swallowing; diarrhea; cough; clay-colored stools or dark urine; chills; burning; abdominal or stomach pain; fever; wheezing

Also, check with your doctor as soon as possible if any of the following side effects occur:

• Less common or rare

• Sore throat; unusual bleeding or bruising ; unusual tiredness or weakness

• Symptoms of overdose

• Clumsiness or unsteadiness; shortness of breath or troubled breathing ; hallucinations (seeing, hearing, or feeling things that are not there); flushing or redness of face; feeling faint; dryness of mouth, nose, or throat (severe); drowsiness (severe); convulsions (seizures); trouble in sleeping

Other side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. However, check with your health care professional if any of the following side effects continue or are bothersome:

• More common

• Drowsiness; increased appetite and weight gain; headache; gastrointestinal upset, stomach pain, or nausea ; dry mouth, nose, or throat ; thickening of mucus

• Less common or rare

• Acid or sour stomach; unusual excitement, restlessness, nervousness, or irritability; tremor; thickening of mucus ; tender swollen glands in neck; stomach discomfort, upset or pain; swollen joints; skin rash; runny nose; ringing or buzzing in ears; nightmares (not with azatadine, chlorpheniramine, cyproheptadine, desloratadine, hydroxyzine

Other side effects not listed above may also occur in some patients. If you notice any other effects, check with your health care professional.

Keep all appointments with your doctor.

Do not let anyone else take your medication.