Zyrtec (cetirizine) is a non-sedating second-generation antihistamine used to relieve symptoms such as sneezing, runny nose, itchy nose and eyes, postnasal discharge, tearing, eye redness, and hives associated with seasonal allergic rhinitis, perennial allergic rhinitis, and hives and itching. 

It works by blocking histamine (H-1) receptors on cells. Histamine is a chemical that is responsible for many of the signs and symptoms of allergic reactions, for example, swelling of the lining of the nose, sneezing, and itchy eyes. Histamine is released from histamine-storing cells (mast cells) and then attaches to other cells that have receptors for histamine. 

The attachment of the histamine to the receptors causes the cells to be "activated," releasing other chemicals that produce the effects that we associate with allergy, for example, sneezing. Zyrtec blocks one type of receptor for histamine (the H1 receptor) and thus prevents activation of H1 receptor-containing cells by histamine. 

Unlike the first-generation antihistamines, Zyrtec and other second-generation antihistamines do not readily enter the brain from the blood, and, therefore, they cause less drowsiness. Zyrtec may cause more drowsiness than other second-generation antihistamines. 

Common side effects of Zyrtec include

• sleepiness,
• dry mouth,
• nausea,
• headache,
• fatigue,
• jitteriness, and
• sore throat.

Serious but rare side effects of Zyrtec include

• allergic reactions,
• seizures,
• fainting, and
• low blood pressure.

Drug interactions of Zyrtec include theophylline, which reduces the breakdown of Zyrtec by 16% and can increase blood levels of Zyrtec. Drugs that cause drowsiness may add to drowsiness resulting from Zyrtec. 

Zyrtec has not been adequately evaluated in pregnant women. Available evidence suggests that risk to the developing fetus is low. 

Zyrtec is excreted in breast milk.  Consult your doctor before breastfeeding. 

Side effects that have been reported with cetirizine include:

• sleepiness (occurs in 14% of patients),
• dry mouth,
• nausea,
• headache,
• fatigue,
• jitteriness, and
• sore throat.

Other important but rare side effects include:

• allergic reactions,
• seizures,
• fainting, and
• low blood pressure

When Using This Product

• drowsiness may occur
• avoid alcoholic drinks
• alcohol, sedatives, and tranquilizers may increase drowsiness
• be careful when driving a motor vehicle or operating machinery

Stop use and ask a doctor if an allergic reaction to this product occurs. Seek medical help right away.

If Pregnant or Breastfeeding

If breastfeeding: not recommended
If pregnant: ask a health professional before use.

No information provided.