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, sneezing, runny nose, 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, nausea, vomiting, 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 foods, preservatives, 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, nightmares or unusual excitement, nervousness, restlessness, or irritability may be more likely to occur in children.

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

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

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, cetirizine, clemastine, cyproheptadine, desloratadine, dexchlorpheniramine, diphenhydramine, or loratadine

• Fast or irregular heartbeat;  fever;  abdominal or stomach pain;  burning;  chills;  clay-colored stools or dark urine;  cough;  diarrhea;  difficulty swallowing;  dizziness;  fast heartbeat;  fever;  headache;  hives;  itching;  prickly sensations;  puffiness or swelling of the eyelids or around the eyes, face, lips or tongue ;  redness of skin;  seizures ;  shortness of breath;  skin rash;  swelling;  tightness in chest;  tingling;  unusual tiredness or weakness;  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;  convulsions (seizures);  drowsiness (severe);  dryness of mouth, nose, or throat (severe);  feeling faint;  flushing or redness of face;  hallucinations (seeing, hearing, or feeling things that are not there);  shortness of breath or troubled breathing ;  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;  dry mouth, nose, or throat ;  gastrointestinal upset, stomach pain, or nausea ;  headache;  increased appetite and weight gain;  thickening of mucus 

•  Less common or rare

• Acid or sour stomach;  belching;  blurred vision or any change in vision;  clumsiness or unsteadiness;  body aches or pain;  confusion (not with diphenhydramine);  congestion;  constipation;  cough;  diarrhea;  difficult or painful urination;  difficulty in moving;  difficult or painful menstruation;  dizziness (not with brompheniramine or hydroxyzine;  drowsiness (with high doses of desloratadine and loratadine);  dryness of mouth, nose, or throat;  early menstruation;  fast heartbeat;  fatigue;  fever;  gastrointestinal upset, stomach pain or nausea;  heartburn;  hoarseness;  increased appetite and weight gain;  increased sensitivity of skin to sun;  increased sweating;  indigestion;  loss of appetite;  joint pain;  muscle aching or cramping ;  muscle pains or stiffness;  nausea;  nightmares (not with azatadine, chlorpheniramine, cyproheptadine, desloratadine, hydroxyzine, or loratadine);  ringing or buzzing in ears;  runny nose;  skin rash;  swollen joints;  stomach discomfort, upset or pain;  tender swollen glands in neck;  thickening of mucus ;  tremor;  unusual excitement, nervousness, restlessness, or irritability;  vomiting  

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.