What are the efficacy and side effects of Cetirizine?

Generally, cetirizine is available in various dosage forms such as tablets and capsules. Its therapeutic effects include alleviating symptoms of allergic rhinitis, relieving skin allergy symptoms, eliminating ocular allergy symptoms, improving respiratory allergy symptoms, and reducing allergic reactions caused by insect bites. Side effects include drowsiness, dry mouth, headache, dizziness, mood changes, etc. It is recommended to use this medication as directed by a physician. Detailed analysis is as follows:

I. Therapeutic Effects of Cetirizine

1. Alleviating Symptoms of Allergic Rhinitis

Cetirizine effectively reduces the symptoms of allergic rhinitis by blocking the action of histamine, thereby making nasal breathing easier and significantly improving patients' quality of life. This enables patients to be free from the disturbances of allergic rhinitis during daily work, study, and life.

2. Relieving Skin Allergy Symptoms

Cetirizine efficiently blocks the effects of histamine on the skin, alleviating symptoms such as itching, erythema, and hives. It helps reduce skin discomfort and promotes recovery to a normal skin condition, decreasing the urge to scratch due to allergies and preventing skin damage and subsequent infections caused by scratching.

3. Eliminating Ocular Allergy Symptoms

Cetirizine effectively relieves symptoms such as itchy eyes, redness, swelling, and tearing by blocking the binding of histamine to H1 receptors in ocular tissues. It protects eye health, prevents long-term allergic reactions from damaging ocular tissues, and maintains normal visual function.

4. Improving Respiratory Allergy Symptoms

Cetirizine blocks the effects of histamine on airway smooth muscle and other respiratory tissues, reducing airway hyperresponsiveness and effectively alleviating symptoms such as wheezing and coughing. It helps improve respiratory function, makes breathing easier, reduces the frequency and severity of asthma attacks, and enhances respiratory comfort and quality of life for patients.

5. Reducing Allergic Reactions from Insect Bites

Cetirizine effectively alleviates local allergic reactions such as redness, itching, and pain following insect bites by blocking the action of histamine. It reduces patient discomfort, prevents secondary skin infections caused by scratching, and promotes healing at the bite site.

II. Side Effects of Cetirizine

1. Drowsiness

Cetirizine can cross the blood-brain barrier and bind to histamine H1 receptors in the central nervous system. Histamine plays an important role in maintaining wakefulness. When cetirizine blocks these receptors, it interferes with the neural pathways responsible for wakefulness, inhibiting the activity of wakefulness-related neurons, thus causing drowsiness, fatigue, and reduced alertness.

2. Dry Mouth

The autonomic nervous system regulates the secretory function of salivary glands. When this regulatory process is disrupted by the medication, it results in reduced saliva production. The lack of sufficient moisture on the oral mucosa leads to a sensation of dry mouth, requiring patients to drink water frequently to alleviate this discomfort.

3. Headache

Cetirizine may affect the regulation of cerebral blood vessels, possibly altering their contraction and dilation states, leading to abnormal vasoconstriction or vasodilation. These changes can cause alterations in cerebral hemodynamics, resulting in headaches. Additionally, the drug may interfere with the balance of neurotransmitters such as serotonin, which are involved in headache regulation, thereby causing headaches of varying intensity among individuals.

4. Dizziness

Cetirizine may affect the vestibular receptors in the inner ear, disrupting the normal function of the vestibular system. The vestibular receptors are responsible for sensing head position and movement changes and transmitting this information to the brain to maintain balance. When the drug causes abnormal signal transmission in the vestibular receptors, the brain receives incorrect positional and motion information, leading to feelings of dizziness, reduced balance, and an increased risk of falls and injuries.

5. Mood Changes

After entering the body, cetirizine may affect the normal function and balance of neurotransmitters such as serotonin and dopamine. Serotonin is closely related to emotional stability and feelings of well-being, while dopamine is involved in regulating emotions and motivation. When the drug interferes with the synthesis, release, or reuptake processes of these neurotransmitters, it may lead to emotional instability, irritability, depression, and other emotional changes, thus affecting mental health.

During cetirizine treatment, patients should avoid engaging in activities that require high levels of concentration, such as driving or operating precision instruments, to prevent accidents caused by side effects like drowsiness and dizziness. If severe discomfort occurs during treatment, medical attention should be sought promptly to adjust the medication regimen.