Antihistamines are common medications used to alleviate symptoms associated with allergies, colds, and other conditions. While generally considered safe, their application in older adults requires careful consideration. This is due to age-related physiological changes that can significantly alter how the body processes and responds to these medications.
Why Antihistamines Pose Unique Risks for Seniors
Older adults experience several physiological changes that can impact how medications, including antihistamines, affect them. Kidney function typically declines with age, which can lead to slower drug elimination and an accumulation of medication in the body. Similarly, liver mass and blood flow may also decrease, affecting the liver’s capacity to metabolize drugs and potentially leading to higher drug concentrations. These changes mean that standard drug dosages might have a more pronounced or prolonged effect in seniors.
Additionally, older adults often exhibit increased central nervous system (CNS) sensitivity to medications. This heightened sensitivity can make them more susceptible to side effects like drowsiness or confusion, even at doses that would be well-tolerated by younger individuals. Changes in body composition, such as an increase in body fat and a decrease in total body water, can also alter how drugs are distributed throughout the body. The issue of polypharmacy, where seniors take multiple medications for various health conditions, further complicates matters by increasing the risk of drug-drug interactions and additive side effects.
Antihistamines to Avoid in Seniors
First-generation antihistamines are generally not recommended for older adults due to their side effect profile. These include common active ingredients like diphenhydramine (Benadryl, Unisom SleepGels, ZzzQuil), chlorpheniramine (Chlor-Trimeton), and doxylamine (NyQuil). These medications are known to easily cross the blood-brain barrier, leading to significant central nervous system effects.
Problematic side effects for seniors include pronounced drowsiness, dizziness, and impaired coordination, which significantly increase the risk of falls. First-generation antihistamines also possess anticholinergic properties, meaning they can block acetylcholine. This can lead to undesirable effects such as dry mouth, blurred vision, constipation, and urinary retention. These effects are often more severe and dangerous in older adults, potentially contributing to cognitive impairment or even delirium. The widespread availability of these first-generation antihistamines in over-the-counter cold remedies and sleep aids makes it important for seniors and their caregivers to carefully check active ingredients.
Safer Antihistamine Options for Seniors
Second-generation antihistamines are generally considered safer and are preferred for managing allergy symptoms in older adults. These medications include loratadine (Claritin), fexofenadine (Allegra), cetirizine (Zyrtec), levocetirizine (Xyzal), and desloratadine (Clarinex). A primary reason for their improved safety profile is their design, which limits their ability to cross the blood-brain barrier.
This reduced penetration into the central nervous system means they are less likely to cause the significant drowsiness, dizziness, and cognitive effects associated with first-generation antihistamines. Second-generation antihistamines primarily target peripheral H1 receptors, which are responsible for allergy symptoms like itching and sneezing, without broadly affecting brain function. While these options are generally non-sedating, some individuals, particularly with cetirizine, might still experience mild drowsiness. Their overall side effect profile is considerably milder, making them a more suitable choice for seniors seeking allergy relief.
Important Considerations When Choosing an Antihistamine
It is always important to consult a healthcare provider before starting any new medication, even over-the-counter options. A healthcare professional can assess an individual’s overall health, existing medical conditions, and current medication regimen to ensure the chosen antihistamine is appropriate and safe.
Reviewing all current medications, including prescription drugs, other over-the-counter products, and herbal supplements, is important to identify potential drug interactions. When starting a new antihistamine, it is often advisable to begin with the lowest effective dose and carefully monitor for any side effects, as individual responses can vary significantly among older adults. Non-pharmacological approaches can also complement medication use, such as minimizing exposure to known allergens (e.g., using air purifiers or keeping windows closed during high pollen seasons) and showering after outdoor activities to remove pollen.