Understanding Hydroxyzine and Levocetirizine
To fully grasp the risks of combining these medications, it's essential to first understand their individual properties and mechanisms of action. Both hydroxyzine and levocetirizine are antihistamines, meaning they block the effects of histamine, a chemical the body releases during an allergic reaction. However, they belong to different generations of antihistamines, which accounts for their varying side effect profiles.
Hydroxyzine (First-Generation Antihistamine)
Hydroxyzine is a first-generation antihistamine, available by prescription under brand names such as Vistaril or Atarax. Its ability to cross the blood-brain barrier contributes to its notable sedative effects. This is why it's not only used to treat itching from allergic conditions but also prescribed for anxiety and as a sedative before and after general anesthesia. The potential for significant drowsiness is a key characteristic of this medication, especially in older adults.
Levocetirizine (Second-Generation Antihistamine)
Levocetirizine, the active isomer of cetirizine (Zyrtec), is a second-generation antihistamine. It is available both over-the-counter and by prescription under the brand name Xyzal. Unlike first-generation antihistamines, levocetirizine is considered less sedating because it penetrates the blood-brain barrier less effectively. It is a potent antagonist of histamine H1-receptors and is widely used for chronic conditions like allergic rhinitis and chronic spontaneous urticaria.
The Dangers of Combining Hydroxyzine and Levocetirizine
Healthcare professionals and drug interaction databases strongly advise against taking hydroxyzine and levocetirizine together for several critical reasons. The main issue is that combining them leads to redundant and potentially dangerous effects without offering any additional therapeutic benefit.
Overlapping Mechanism of Action: Since both are antihistamines targeting the same histamine receptors, taking them together is essentially doubling up on the same type of medication. This is known as a duplication of therapy and increases the risk of side effects.
Exacerbated Central Nervous System Depression: The most significant risk is the additive CNS depressant effects. Both drugs can cause drowsiness, dizziness, and impaired coordination, with hydroxyzine being a major contributor. When taken together, these effects are significantly heightened. A study on chronic spontaneous urticaria found that adding hydroxyzine to levocetirizine did not improve efficacy but increased daytime somnolence.
Impaired Cognitive and Motor Function: The severe drowsiness and dizziness can impair judgment, thinking, and psychomotor skills. This can make it unsafe to perform activities that require mental alertness, such as driving or operating heavy machinery.
Increased Risk of Accidental Injury: The combination of excessive sedation and impaired coordination can increase the risk of falls and other accidents, especially in vulnerable populations like the elderly.
Comparison Table: Hydroxyzine vs. Levocetirizine
| Feature | Hydroxyzine | Levocetirizine (Xyzal) |
|---|---|---|
| Generation | First-generation | Second-generation (active isomer of cetirizine) |
| Sedation Level | High (frequently causes drowsiness) | Lower (less sedating) |
| Uses (Allergy) | Itching, hives, other allergic conditions | Allergic rhinitis, chronic spontaneous urticaria |
| Other Uses | Anxiety, sedation before/after anesthesia | Limited to allergic conditions |
| Availability | Prescription only | Prescription and Over-the-Counter |
| Risk of Overlap | High (causes significant CNS depression) | Low (less CNS penetration, but additive effects occur with other depressants) |
| Recommended for Combination? | No | No |
When to Seek a Doctor's Advice
If your current allergy medication is not providing sufficient relief, it is essential to consult a healthcare provider instead of attempting to combine medications on your own. A doctor can properly assess your symptoms and determine a safer and more effective treatment plan. Possible alternatives include:
- Adjusting the dosage or timing of a single antihistamine.
- Switching to a different class of medication, such as a nasal steroid spray.
- Exploring other non-sedating options like fexofenadine (Allegra) or loratadine (Claritin).
- For severe or chronic conditions like urticaria, a specialist may consider alternative treatment strategies.
Proper Protocol for Using Antihistamines
Inform Your Doctor: Always inform your healthcare provider of all the medications, supplements, and herbal products you are taking.
Read Labels Carefully: Be vigilant when using over-the-counter allergy products. Many combination cold and flu medications also contain antihistamines.
Be Aware of Alcohol: Avoid or limit alcohol consumption while on these medications, as it significantly increases CNS depressant effects.
Monitor for Side Effects: Report any adverse effects like excessive drowsiness, dry mouth, or changes in heart rate to your doctor.
Conclusion
In summary, it is not advisable to take hydroxyzine and levocetirizine together. While both are effective antihistamines, their similar actions and shared sedative risks make their combination redundant and potentially dangerous. The heightened risk of central nervous system depression, leading to impaired cognitive and motor function, far outweighs any potential benefit. For individuals struggling to control allergy symptoms, the best course of action is to seek guidance from a healthcare professional to explore safer and more appropriate treatment alternatives.
