If you suffer from hay fever, you probably run to the pharmacy to get a new batch of antihistamine tablets at the first sight of pollen… and the fact that researchers don’t really know why your body has such an extreme reaction to such a harmless product is probably no help at all! You may experience sneezing, running nose, headaches, itchy and watery eyes and in extreme cases, it may even cause breathing difficulties.
This happens because your immune system reacts to pollen (or other offenders), stimulating the release of histamine. Upon release, histamine causes pandemonium in your nose and throat, causing them to swell and stimulating mucus production. The most obvious way of preventing your body to react in such a way is to block histamine release, which is exactly what antihistaminics do. It all seems perfect, but unfortunately your hay fever treatment comes at a cost and these drugs can have some unpleasant side effects, ranging from drowsiness, dry mouth, and constipation to more severe heart irregularities.
To avoid these issues, recent years have seen a boom in natural allergy products, which have become the second largest most popular treatments in alternative medicine, after back pain treatments. The most common way to assess their viability is by conducting double-blind studies, in which two groups of patients are given either the product to test or a placebo with no antihistaminic action. At the end of the study, the effectiveness of the tested product is assessed in terms of how much better it was than the placebo. However, this is only the first step. Once a certain product is recognised as having antihistamine action, further studies are required to study mechanisms of action. Unfortunately, these types of studies are very limited in natural products, and all we can do at the moment is speculate.
One of the most used natural antihistamines, and probably the most studied, is butterbur (Petasites hybridus). Several double-blind studies have shown that this plant has strong anti-histaminic properties (Schapowal et al, 2004) similar to that of standard antihistamines – cetiruzie (Zyrtec, Schapowal et al., 2002) and fexofenadine (Allegra, Lee et al., 2004), with the advantage of showing less adverse effects. Other products with proven antihistaminic properties include Thymomodulin, a thymus extract (Marzari et al., 1987), nettle leaf (Mittman et al. 1990) and probiotics (Bifidobacterium longum strain BB536, Xiao et al., 2006). In all cases, participants in these studies experienced a reduction if hay fever symptoms, with less sneezing and running nose. Also, apparently in addition to its aphrodisiac properties (hence the name!), horny goat weed also has similar properties. In addition to reducing symptoms, this plant, mixed with other ingredients, reduced levels of immune cells associated with allergic reactions (Yu, 1989).
Although increasingly more popular in the westernised world, most natural antihistamines were identified and its use developed in Asian countries, where there’s a long tradition of opting for such products. Examples of this include Guduchi (Tinospora cordifolia, Badar et al., 2005) and Tylophora (Gopalakrishnan et al., 1990), which are herbs used by doctors in India to treat people with allergies. Also, the fruit hull of mangosteen (Garcinia mangostana, Nakatani et al., 2002) has been used as a antihistamine in Thai indigenous medicine for many years. And from Japan comes sho-seiryu-to, which has been shown to combat hay fever symptoms (Baba and Takasaka, 1995). Sho-seiryu-to is made of licorice, cassia bark, schisandra, ma huang, ginger, peony root, pinellia, and asiasarum root.
Quercetin is a natural antioxidant present in many fruits, vegetables, leaves and grains. In vitro studies suggest its potential as an antihistamine given that it can inhibit histamine release (Otsuka et al., 1995). Although no further studies have been done, it is becoming very popular amongst hay fever sufferers. And finally, although surrounded by some controversy, there’s vitamin C. Fortner et al. (1982) didn’t detect any improvement caused by this vitamin in relation to placebo group, but a few years later, Podoshin et al. (1991) identified reduced nasal secretions, blockage and edema in patients that had been treated with vitamin C.
These studies show that many of these medicinal plants and herbs can provide relief of hay fever symptoms, similar to antihistamine pills, possibly with the advantage of less adverse secondary effects. However to fully understand how they work, it’s necessary to identify the active components responsible and their mechanism of action. It is most likely that each natural antihistamine has different pathways to combat symptoms, which would explain different efficacies. Modes of action may range from decreasing the viscosity of mucus to prevent secretion of histamine.
Throughout the history of medicine, the active element of many drugs has been identified from natural products used in traditional medicine. It is, therefore, important to continue research on how some of these natural antihistamines work, and it just may be possible to find additional effective medicines to treat allergies.