The chief advantage of second-generation antihistamines is that they tend to produce substantially less drowsiness than older antihistamine drugs (such as Benadryl). They also last longer, so you only need to take them once a day.
How Antihistamines Work
Your body has four different types of histamine receptors on your cells. Receptors are like communication pathways that allow signaling from outside the cell to the inside of the cell. These four histamine receptors allow the body to communicate important information to the cells of your body to maintain healthy functioning.
Histamines cause the following things to occur:
SwellingActivation of pain receptorsItchinessRednessContraction of smooth muscles (present in airways, intestines, bladder, and blood vessels)
Antihistamines are medications that block the communication pathway between the body and the cell by occupying the space that the histamines would have used to signal the cell. Antihistamines therefore prevent swelling, pain activation, itchiness, redness, and smooth muscle contraction from occurring. As such, antihistamines can be useful in treating:
Rhinorrhea Bronchoconstriction (tightening of the airways) Anaphylaxis Conjunctivitis Urticaria (hives)
You should know that while antihistamines can treat the above conditions, they may not be the preferred or safest option. For example, antihistamines are not the best option for treating anaphylaxis and bronchoconstriction.
Who Can Take Zyrtec?
Zyrtec can be taken by most healthy individuals who are at least 6 months old and have never had an allergic reaction to Zyrtec or any medication including the generic form, cetirizine HCl.
Talk to your healthcare provider before taking Zyrtec if you are pregnant. Animal studies have shown no risk to fetuses, but controlled human studies are lacking.
It is generally recommended that you not take Zyrtec while breastfeeding.
Tell your healthcare provider about any medications you are taking before starting Zyrtec, including prescription and over-the-counter medicines, nutritional supplements, and herbal products.
How to Take Zyrtec
Zyrtec comes in several different doses and forms including tablets, chewable tablets, and syrup. It is taken once per day, usually in 5 or 10 mg doses, but this varies depending on your age and weight. For this reason, it is very important to read the instructions very carefully before taking Zyrtec. If you are confused speak with a pharmacist.
Side Effects
Side effects include drowsiness, dry mouth, dizziness, and pharyngitis (inflammation of the throat which may cause tonsillitis or sore throat; it is interesting to note that this effect may actually be caused by your allergies and not the medication).
Symptoms of an allergic reaction to Zyrtec include swelling, hives, difficulty breathing, or wheezing and require immediate medical attention. Less common side effects included a stomach ache, irritability in small children, headache, diarrhea, and bloody noses. Read the package insert for a more complete list of side effects.
Other Precautions
Zyrtec (and other antihistamines) do not prevent the serious allergic reactions known as anaphylaxis, and should not be used as a substitute for the epinephrine which healthcare providers often prescribe for this condition.
