What's In a Cough? An Introduction to Herbal Expectorants
by Shayne Foley

While modern science is still unraveling the intricate relationship between the nervous system and other body systems, it appears that some type of nervous reflex is involved with several herbal actions. Taste buds registering ‘bitter’ trigger a vagus nerve response, activating digestive secretion throughout the GI tract. Likewise, the soothing, demulcent influence of mucilage-containing herbs on the throat can induce a reflex impulse that results in relaxation and soothing of the respiratory tissue. And, by activating the upper digestive tract, stimulating expectorants can also cause the nervous system to trigger expectoration. In the next few paragraphs, we’ll look briefly at three main categories of herbal expectorants to better understand and use these valuable and widely mis-understood respiratory herbs.

Expectorants
Expectorants often work by thinning respiratory secretion, allowing mucous to be dislodged and expelled upward by the three hundred million, or so, tiny cilia that line much of the lower respiratory system. In essence, expectorants help a cough to become more ‘productive.’ While their broader actions do vary considerably, expectorants can be loosely categorized as reflex or direct. They might also be further classified as stimu-lating or relaxing expectorants, depending on their understood impact on the physiology.

Stimulating Reflex Expectorants
Most stimulating reflex expectorants appear to work by activating the tissue of the upper digestive tract. This explains why herbalists have traditionally used low-dose emetics (herbs that induce vomiting) to activate the reflex response and produce expectoration. Full emesis (vomiting) was also traditionally relied upon with acute respiratory congestion. Of course, Lobelia (Lobelia inflata) comes to mind in this regard, as does Ipecac (Cephaelis ipecacuanha) and Horehound (Marrubium vulgare). Cowslip (Primula veris), Snake root (Polygala senega), Elecampane (Inula helenium), Bloodroot (Sanguinaria canadensis), and Soapwort (Saponaria officinalis) are also used as stimulating expectorants. Licorice root (Glycyrrhiza glabra) is also considered to be a stimulating expectorant, although it probably does not stimulate in the same way as the other herbs mentioned here. It is certainly more soothing. Herb Pharm’s Friar’s Balsam is a traditional blend of plant extracts that has long been valued for their stimulating expectorant quality.

Relaxing Reflex Expectorants
Relaxing reflex expectorants also loosen respiratory congestion by making secretions less viscous. They also work to relax the respiratory tissue and are often used to soothe dry, irritated coughs, as well as to relieve congested coughs. A number of soothing relaxing expectorants are rich in mucilage, including Mullein (Verbascum spp.), Iceland Moss (Cetraria islandica), and Marshmallow (Althea officinalis). Ginger (Zingiber officinalis), Wild Cherry bark (Prunus virginiana), Skunk Cabbage (Dracontium fœtida), and Pleurisy root (Asclepius tuberosa) are also widely used as relaxing expectorants.

Direct Expectorants
While most stimulating or relaxing expectorants appear to exert their influence via a nervous reflex response, direct expectorants operate by physically encountering the respiratory tissue, either via partial excretion through the lungs or via steam inhalation. As a rule, direct expectorants are volatile-oil containing herbs. Many, as a result, also possess some degree of antiseptic activity. Thyme (Thymus vulgaris), Anise (Pimpinella anisum), Eucalyptus (Eucalyptus globulus), Pine (Pinus pumilio), and Garlic (Allium sativum) are all direct expectorants that have a long history of use. They can all be taken internally or used externally, as a chest-rub or herbal inhalant.

When using expectorants, always approach them with their peripheral benefits in mind. This principle can be applied to all herbs. Learn to differentiate between them. The categories we have looked at here are useful to know, but should only serve as a simple starting point. When do you use Lobelia over Licorice? Ginger over Mullein? Anise over Garlic? That’s the art of herbalism, and the subject of another article.