Atchoo! How Antihistamines Age Us.
In Traditional Chinese Medicine (TCM) Fall is the season of dryness making it the perfect time to discuss anti-histamines. I know that’s challenging for many of us in the PNW to accept since that’s when the rain starts up again. But do remember that leaves dry up and fall off trees in the autumn, even here. And what does that have to do with anti-histamines? jAntihistamines are drying. And drying is what happens for many of us as we age. It becomes uncomfortable at a certain point but as their antihistamine is "safe" many people don't connect their painful dry eyes with their daily use of an antihistamine for a decade. A little context, shall we?
Your body produces histamines for a number of reasons but notably as an allergic response. Receptors for histamines exist all over the place and in some unexpected locations if you've only thought of histamine as associated with allergies: vascular smooth muscle, airway smooth muscle, mucous glands, and sensory nerves. It’s those mucous glands that get most of the attention because they sense the histamine, start pouring out mucous, and suddenly you are clogged up. Anti-histamines stop this cascade of events and provide allergy sufferers with relief. They also have some anti-inflammatory effects, which is useful because part of that plugged nose feeling is inflamed, swollen nasal passages with less volume for air flow. This is possible because your nose has sensory neurons that possess histamine receptors. Remember though that it’s not just your nose that has these receptors. You have sensory nerves and mucous membranes in a lot of places.
One place you might not expect to find histamine receptors is in your brain. What are they doing there? Histamines in your brain contribute to regulating your sleep/wake cycle, reinforce learning and memory, balance fluid, and regulate things you need your body to do but don’t think about: control temperature, circulate blood, and release stress hormones. Some antihistamines are able to cross the blood-brain barrier and get involved in your brain’s histamine system and these functions. You know this because some antihistamines make you drowsy. What you might not also notice is the impaired concentration, learning/memory and sleep quality that comes from taking antihistamines at night.
Um, what? Some of you reading this are taking anti-histamines as “safe” sleep aids. (Actually, a lot of you). Without them you can’t fall asleep. It’s true they will increase the sensation of drowsiness. Additionally,”[w]hen taken at night, [some] antihistamines increase the latency to the onset of rapid eye movement [REM]sleep and reduce [its] duration…. The residual effects of poor sleep, including impairment of attention, vigilance, working memory, and sensory-motor performance, are still present the next morning.” In other words, they help you fall asleep but the quality of sleep is really poor, something like falling asleep after having alcohol. So, you don’t feel rested and the cycle perpetuates itself. Moreover, the effects of these antihistamines on “learning and examination performance in children and on impairment of the ability of adults to work, drive, and fly aircraft” are, in a word, “detrimental.” Overdose can alter your heart rhythm and other mechanisms in your body leading to death. So, while not addictive like most sedatives prescribed for sleep, “safe” does not mean without side effects.
Some newer antihistamines do not cross the blood-brain barrier and therefore aren’t interfering with those activities. They do still circulate in your body and impact histamine receptors wherever found, not just in your nose. These histamines are the drug of choice for urticaria (hives) and allergic rhinoconjunctivitis (hay fever) and I’m glad we have them. Let’s give some thought though to what happens if you take either sort of histamine on a long-term basis, not just for a week or so to take care of some hives, however.
Mucous membranes through out your body are impacted by the antihistamines you take to dry up your nose. For instance, your eyes, vagina, and/or throat may get uncomfortably dry. Skin dries out and our culture spends a fortune on anti-wrinkle moisturizers to stay young while pumping in drying antihistamines. While this is a natural progression in aging, antihistamines taken long term accelerate this drying process because they don't just target your stuffy nose; they impact histamine receptors wherever found in your body.
In TCM dryness is often referred to as a Yin Deficiency. When I look in the index of one of my favorite TCM reference books (Maciocia, The Practice of Chinese Medicine, 2nd ed, 2008) here’s what I see under Yin Deficiency: chronic fatigue syndrome, constipation, empty heat, headaches, mind unsettled, mind weakened, headaches, and mental emotional problems. Dryness will also contribute to night sweats and hot flashes, which do not promote restful slumber.
Insufficient fluid in your body is a systemic problem. Many people taking antihistamines as sleep aids then wonder why they continue to have difficulty falling asleep, and continue taking antihistamines to help. Their solution is directly contributing to their mind being “unsettled” and making it hard to fall asleep. Making them too hot at night to get comfortable, or waking due to a dry cough. Probably once in a blue moon to adapt after jet lag this is a feasible use of antihistamines. Long term use as a “sleep aid” is digging yourself a bigger hole. Folks taking them for year-round allergies have many of these same problems. They may be using the newer antihistamines to avoid the sleep and cognative impacts but they still will be promoting systemic dryness.
By all means, take antihistamines when appropriate. But if you’re a long-term user interested in reducing your reliance on antihistamines, see your acupuncturist. There are a variety of options in TCM including dietary suggestions, acupuncture, and herbal remedies.