Antihistamines

Antihistamines

Between 15% and 25% of the population around the world suffers from periodic allergic rhinitis. It can be occasionally annoying or severe enough to affect the quality of life. Antihistamines are the primary medication used to treat this and other forms of allergy.1

The older types of these medications, the first-generation antihistamines, are sedating. For that reason, they tend to be used more often as sleeping pills. Indeed, some 12% of those over age 65 take such medications for insomnia. This is concerning since over-the-counter sleep medications with the antihistamines diphenhydramine (Benadryl) and doxylamine (Unisom) are on the Beers List – medications to be avoided in those over age 65 because they can cause difficulty with thinking, problems with coordination, can worsen kidney or liver insufficiency, and lead to dizziness and falls. They are a common source of drug interactions including with some antidepressants and cardiac medications.2

Antihistamines are one of the most commonly prescribed drugs for children. Per a Cochrane Review (medical studies that are well-known for their scientific analysis and for thoroughness), the effectiveness of antihistamines for treating nonspecific cough in children is not certain. Also, children are more susceptible to antihistamine adverse effects, including sedation as well as paradoxical agitation and excitability.3   Topical antihistamines should be avoided in children

Some people also take antihistamines for their cold symptoms. While the older, first generation antihistamines may dry secretions, they can thicken the mucus excessively so that it is harder to cough them up.3

     Antihistamines are effective in the treatment of allergic rhinitis and chronic urticaria. For chronic allergy symptoms, regular use of an antihistamine is probably more effective than taking them only as needed. Allergic conjunctivitis is probably better treated with antihistamine eye medications. Antihistamine effects vary from person to person so if one type doesn’t help, another may. 4, 5

First generation antihistamines are not recommended because they can cause sedation as well as difficulty thinking. These medications should be avoided not only in those over 65 years of age, but also those with glaucoma, constipation, dementia, or benign prostate enlargement. Second generation antihistamines are much less likely to cause sleepiness but it can have this effect in some, especially in higher doses.5

Because many types of antihistamines are sold without a prescription, it is essential to discuss any use of them with your pharmacist so that they can determine if there are any interactions with your prescriptions. And remember, it is far superior to try to determine what is causing an allergic reaction and make every effort to eliminate exposure to such.

This article is not intended to replace your health care provider. The intent is to make important information about medications available.

References

1D. Passali, et al, “The International Study of the Allergic Rhinitis Survey:  outcomes from 4 geographic regions,” Asia Pacific Allergy, January, 2018; 8 (1): e7.

2O. Abraham, et al, “Over-the-Counter medications containing diphenhydramine and doxylamine used by older adults to improve sleep.” International Journal of Clinical Pharmacy 297; 39(4) 808-817.

3J. Van Schoor, Antihistamines:  A brief review, Professional Nursing Today, 2012: 16(5).

4Dr. Koop’s Self-Care Advisor. Time Life Medical Books, 1996.

5The Merck Manual, 19th edition. Whitehouse, New Jersey:  Merck, Sharp and Dohme, 2011.

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Medications that increase the risk of falling

Medications that increase the risk of falling

There are several ways medications can make a fall more likely to occur. One such way is by causing sedation or confusion. When there is decreased vigilance, things like rugs or clutter are more apt to go unnoticed or interpreted as an obstacle. Alcohol alone or combined with such medications can worsen such hazards. Other medications interfere with a smooth, coordinated gate. Other medications cause orthostatic hypotension. Aging and some diseases can also produce this effect. With changing position to one that is more upright, such as from lying flat to standing, a lot of blood pools in the lower legs. That leads to less blood returning to the heart and thus less pumped to the head and upper extremities. Normally the body can correct for that change quite quickly. Orthostatic hypotension refers to a lack of such a rapid adjustment.

In “Evaluation of the Medication Fall Risk Score” by C. Yazdani and S. Hall (American Journal of Health System Pharmacy, 1/1/2017, e32-39), the medications that are most likely to increase the risk of falls are sedating medications (for example opiates and opioids), some of the antidepressants, certain medications used to treat epilepsy, drugs used to treat psychosis, NSAIDs (non-steroidal anti-inflammatory drugs), and some of the antihypertensive agents.

There are some medications that have what is called an anticholinergic effect. This is a technical term referring to the suppression of the “rest and digest” state of the automatic nervous system. Not many drugs have this as their intended outcome, rather it is a property of a drug that can’t be removed, so to speak. Some of the medication classes listed above have this effect and one member of the drug class may have a stronger anticholinergic effect than another. For example, some tricyclic antidepressants (TCAs) have a prominent anticholinergic effect while another TCA doesn’t. Anticholinergic effects include dry mouth, constipation, sedation, tachycardia (rapid heartbeat) and pain from light from a diminished ability of the pupils to constrict.

Older antihistamines often have such an effect, so keep this in mind when taking diphenhydramine and other such drugs. “Use of medications with anticholinergic-activity and self-reported injurious falls in community-dwelling Elderly” (by K. Richardson, et al, in Journal of the American Geriatrics Society, 63:1561-69, 2015) included research that looked at this important contributor to falls. The authors noted that anticholinergics can increase the fall risk because of sedation as well as possible confusion and blurred vision. They also noted that older individuals tend to have the most problems with anticholinergics.

Considering that one-third of those over age 65 fall each year, this is no small matter. This 2013 CDC fact was noted in “Urological Implications of Falls in the Elderly:  Lower Urinary Tract symptoms and alpha-blocker medications” (L. and J. Schimke, Urologic Nursing, September and October, 2014, pages 223-229). Nocturia – having to get up at night to urinate, as well as urge incontinence (having a sudden intense need to urinate) make falls more likely. Unfortunately, a medication sometimes prescribed for older men with prostate problems – alpha blockers, can cause orthostatic hypotension and thus also contribute to falls. Some of the medications used for urge incontinence have anticholinergic properties that can increase the fall risk. So be careful not to substitute one cause of falls for another.

This article is not intended to replace your health care provider. The intent is to make important