Expectorants
EXPECTORANTS AND RESPIRATORY TRACT FLUID
Bone & Mill, in their book, Principles and Practice of Phytotherapy,have this to say about expectorants:
Overview of Expectorants
- An expectorant is a substance that enhances those physiological mechanisms by which respiratory tract secretions are cleared from the lungs. In the course of doing this they often render the consistency of respiratory tract secretions more fluid and/or more demulcent. They do not necessarily increase the quantity of coughed-up phlegm, nor are they necessarily antitussive.
- Since reflex and warming expectorants act by different mechanisms, and on different parts of the lung tissue, an effective herbal prescription can combine these two types of expectorants but depending on the patient’s condition.
- The effect and mechanism of action of reflex expectorants have been demonstrated by scientific experiments. However, since their effect seems to involve vagal stimulation of secretory glands, there may also be vagal stimulation of smooth muscle tissue in the lungs. Hence, they should be used with caution in asthma, and combined with bronchiolar spasmolytics (but not anticholinergics that can dry respiratory secretions)
- Many lower respiratory tract disorders will benefit from the action of expectorants, but particularly those where mucus is tenacious and difficult to cough up. However, it depends on the cause of a cough whether an expectorant action is also antitussive.
The dictionary meaning is only concerned with the actual oral production of phlegm or sputum. Since the majority of mucus produced from the lungs is swallowed, this definition is clearly unsatisfactory. The best definition comes from Brunton, a 19th century pharmacologist. Brunton’s functional definition best explains the various ways in which medicinal plants can act as expectorants.
Brunton (1885): “Remedies which facilitate the removal of secretions from the air passages. The secretion may be rendered easier of removal by an alteration in its character or by increased activity of the expulsive mechanism.”
Why Expectorants?
Many respiratory conditions are characterized by abnormal mucus (catarrh) that can narrow airways. This abnormal mucus may be thick and tenacious and hence very difficult to clear from the airways. If expectorants can render this catarrh more fluid and/or assist in its expulsion, then a clinical benefit should be achieved.
Increases the flow of mucous from the membranes. May do so through tonification or relaxation. Effect is not necessarily limited to or focused on the lungs, although this is the general usage. Most of these herbs affect any and all of the mucous membranes.
Expectorants can help to relieve debilitating cough. The presence of an irritation in the airways (such as tenacious abnormal mucus) involves the cough reflex. (The cough reflex is most sensitive in the trachea and larger airways. The sensitivity progressively decreases in the finer airways and in the very fine airways there is no reflex at all. So, in alveolitis, there is little stimulation of the cough reflex, whereas for tracheitis the stimulus is strong.) By clearing abnormal mucus or by changing its character and making it more demulcent, expectorants can allay cough and are therefore antitussive.
Expectorants: Herbs to Promote Expectoration, Resolve Phlegm, Relieve Coughing
These herbs exert a stimulating action on the bronchi that makes it easier for the body’s natural response, coughing, to engage. They merely encourage and amplify the response of the body’s vital force to bronchial irritants.
When bronchial mucus fails to metabolize, or when its production slows down, it no longer serves a normal protecting and moistening function. It stagnates and thickens or hardens instead and becomes sputum, an injurious substance. Sputum hinders normal secretion and provides an ideal environment for bacteria and other toxins which can turn into infection. If sputum accumulates over a long time it can cause serious chest fullness, asthmatic breathing, chronic bronchitis or bronchial asthma. In this case, the emetic treatment may also be used.
There are three main categories of herbs:
- Pungent, stimulating warm expectorants
- StimulatingReflex Expectorants
- Relaxingcool expectorants
Additionally, there are mucolytic expectorants:
Mucolytic expectorants treat lung phlegm dryness which can follow external exposure to a hot or dry wind or internal conditions such as lung Qi constraint and lung phlegm damp. Lung Qi constraint involves spasmodic asthma, a nervous condition affecting the lungs over a long period of time. There may be mental or emotional holding, chest distension with pain, asthmatic breathing with wheezing and a wiry pulse. It can also represent a condition that has been driven inwards causing asthma (allergic asthma), which can arise after influenza, pneumonia, tuberculosis (especially after antibiotic treatment)
If lung phlegm dryness follows lung phlegm damp as in chronic bronchitis, anti-infective and stimulant expectorants that transform phlegm cold should also be used. Lung phlegm dryness always presents with difficult expectoration, coughing up hard plugs of sticky sputum, with difficult, dry, often unproductive cough…even if an external cause triggered it like a dry wind.
Treatment Goals: aimed at several levels.
If lung Qi constraint is at the root, use herbs that circulate lung Qi (see the section on respiratory relaxants). If the cause is an allergic diathesis, reducing the allergy becomes the priority. In all cases, the viscous bronchial sputum needs softening, loosening, eliminating with mucolytic expectorants which contain saponins..examples: Mullein leaf, Cowslip root, Birthroot, Grindelia herb. All forms of lung dryness call for the additional support of bronchial demulcents (in another section)