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Appropriate use of second-generation antihistamines

Second generation antihistamines have largely replaced first-generation antihistamines, for several reasons. Unlike the older agents, they have no appreciable effect on the central nervous system and therefore produce little or no sedation or anticholinergic effects. They are also longer-acting, and some of them have anti-inflammatory and antiasthmatic effects. In addition, the manufacturers are marketing them heavily to physicians and the general public, and patients are therefore asking for them by name.

We ought to keep several things in mind when prescribing these drugs. In some situations sedation is desirable, and first-generation antihistamines are often prescribed specifically…

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Articles of Interest

Second generation antihistamines: an update

First generation antihistamines have major unwanted effects, including sedation, weight gain and anticholinergic effects. Second generation H1-antihistamines (SGAHs) are free from the unacceptable side effects of the first-generation ones and are now preferred by physicians and patients as first line therapies. SGAHs have a good absorption profile, whenever administered orally, with effective plasma concentrations being reached in most of them within 3 hours after dosing. Their liposolubility permits the crossing of cell membranes, helping their bioavailability.

Should I Take Allegra, Claritin, or Zyrtec?

Claritin, Zyrtec, and Allegra are all good antihistamine options and are generally well-tolerated by many people. But there are some differences between them that may make one of these antihistamines better for you than the others. For example, Zyrtec and Allegra may work faster than Claritin. Zyrtec and Claritin can make you sleepy, while Allegra usually won't.

Antihistamines: if/when are first generation medications advantageous over newer antihistamines?

Answer: Newer antihistamines are long-acting, which is a significant advantage for management of urticaria, pruritus and allergic rhinitis, and they are more efficacious than first-generation antihistamines. Newer antihistamines are less likely to have clinically significant drug interactions than older antihistamines and the newer agents do not carry the risk of toxicity and death that has been associated with first-generation antihistamines. As you noted, the newer generation antihistamines have favorable side effect profiles to first-generation antihistamines.

Antihistamines: Zyrtec vs Allegra vs Claritin vs Xyzal vs Benadryl

Some newer antihistamines, known as second generation antihistamines, cause less sleepiness than older products. Examples include cetirizine (brand Zyrtec), fexofenadine (brand Allegra), levocetirizine (brand Xyzal) and loratadine (brand Claritin). These antihistamines usually last 12 to 24 hours. Everyone’s body is different so there unfortunately is not a magic formula to determine which antihistamine works best for each person. Cetirizine is the most potent of the antihistamines having the strongest binding to histamine receptors but can have a mild sedative effect in some individuals, so it’d be best to take at nighttime. That said, cetirizine may not have the strongest effect in everyone’s body.

First- or second-generation antihistamines: which are more effective at controlling pruritus?

No evidence-based guidelines or consensus statements were found that address antihistamine preference in the treatment of pruritus.

Perspectives on Second-Generation OTC Antihistamines

Both first- and second-generation antihistamines alleviate AR symptoms or other upper respiratory allergies. First-generation OTC antihistamines include diphenhydramine (eg, Benadryl), chlorpheniramine (eg, Chlor-Trimeton), and clemastine (eg, Tavist); second-generation products include fexofenadine (eg, Allegra), loratadine (eg, Claritin and Alavert), and cetirizine (eg, Zyrtec).

Safety of second generation antihistamines

The sedation related to first-generation antihistamine use has been shown to compromise performance at school and at work, impair driving, and decrease the ability to handle tasks that require a high degree of alertness or concentration. Second-generation antihistamines are less likely to produce sedation. Loratadine, cetirizine, and fexofenadine are the most commonly prescribed second-generation antihistamines.

What Are Second-Generation Antihistamines? Defining Second-Generation Antihistamines

The most common side effects of second-generation antihistamines include dry mouth, headache, and dizziness. Serious side effects are rare but may include difficulty breathing or rapid heart rate.

What’s the Best Non-Drowsy Antihistamine for Allergies?

Second- and third-generation antihistamines are less likely to cause drowsiness. Of these, cetirizine works the fastest but has a higher chance of making you feel drowsy. Fexofenadine is the least drowsy option. We can’t say for certain which non-drowsy antihistamine is best for allergy symptoms. If one antihistamine doesn’t provide relief, you may need to try another to find the best fit.

Resources

Allegra

Allegra stays out of your brain Get fast*, powerful, non-drowsy allergy relief with 0% brain interference.

Claritin

Claritin® is the No. 1 doctor-recommended non-drowsy oral OTC allergy brand. It is an effective antihistamine that relieves allergy symptoms such as itchy eyes, nose and throat, sneezing, and runny nose for up to 24 hours. Claritin® products are available in several forms, dosages and flavors for adults and children.

Zyrtec

ZYRTEC® is an over-the-counter medicine that provides effective, 24-hour relief of indoor and outdoor allergy symptoms.