Asthma is an obstructive lung disorder that affects the normal functioning of the bronchi. The bronchi contain smooth muscle in their walls that control the entry of air into the lungs by the contraction or relaxation. The bronchi also have a role in warming and humidifying the air that enters the lungs, the removal of particulate matter, and the cough reflex (1). When these are not functioning properly, breathing can become difficult and laboured.
Approximately 5.4 people in the UK have asthma, which is 1 in every 12 adults and 1 in every 11 children. The condition is considered to be lifelong in most people, although people who develop asthma as children may find it goes away as they grow into adulthood (2). The prevalence of the disease has steadily increased since the second half of the last century (4).
There are various types of asthma, that indicate their development, triggers, and severity.
Allergic asthma is triggered by an allergen, and occurs more often in people who have another allergic condition such as hay fever, eczema and food allergies.
Seasonal asthma is only triggered at certain points in the year. This may be associated with seasonal allergies (such as to mould spores), or cold air.
Occupational asthma is when the disorder is directly caused by the environment the person is working in, and thus is typically diagnosed in adulthood. This may be a type of allergic asthma. The allergy could be, for example, to flour dust or latex dust (3).
Exercise induced bronchoconstriction is when asthma-like symptoms follow exercise, and is often a phenomenon found in athletes or others who frequently do strenuous activities. Exercise is inherently inflammatory and in this condition is more likely to cause broncho-constriction (3).
In difficult and severe (also known as brittle) asthma symptoms are difficult to control. Difficult asthma may require treatments in addition to inhalers. Severe asthma occurs in 4% of asthma sufferers and is diagnosed by a specialist. Those with severe asthma are treated with a class of drugs known as biologics, as even high doses of steroids do not control symptoms (3).
Asthma is treated with a variety of drugs, depending on how frequently symptoms are experienced and how well they are controlled.
- Step 1: Short acting beta-receptor agonist – This is an inhaled medication that is short-acting and considered a reliever therapy as it is a bronchodilator. This is prescribed to people with occasional, easily controlled symptoms, or in conjunction with other therapies. Ventolin and Salbutemol are in this category. These inhalers are often blue.
- Step 2: Inhaled corticosteroids – This is considered a preventer therapy, that is often used in addition to a reliever. Corticosteroids are anti-inflammatory. They may be added if the patient needs to use their preventer more than three times per week, is awakened by their asthma once per week, or who have recently experienced an exacerbation in symptoms. These inhalers are often brown or red.
- Step 3: An add-in therapy of a long-acting beta-receptor agonist, which is inhaled as a reliever. This may be in addition to inhaled corticosteroids. These inhalers are often purple.
If these steps do not sufficiently control symptoms, then a higher dose of the inhaled corticosteroid may be recommended with daily oral prednisolone (4).
How does asthma happen?
Asthma occurs due to the way the airways over-react to triggers (airway hyperactivity). Many of these triggers are also allergens, but can be pollution, cold air, exercise, and respiratory infections (2). The relationship between atopy, which is the tendency towards allergies and eczema, and asthma is well-established. Atopic individuals are sensitive to potential allergens. These allergens may be pollen house dust mites, pets, cockroaches, mould spores, or medication (4). Allergen inhalation initiates the release of histamine and other bronchoconstrictory agents, which also alter consistency of the mucus. The airways get narrower, and breathing becomes difficult.
In exercise-induced asthma, the hyperventilation from the exercise causes the loss of moisture in the lining of the respiratory tract. This can trigger a release of inflammatory chemicals. Additionally, rapid heat changes in the respiratory tract may cause irritation (4).
The examination of the airways of asthmatic patients has revealed acute inflammation and immune cells. Increased numbers of mast cells, lymphocytes and eosinophils have been observed by bronchoalveolar lavage, in addition to macrophage activation. These observations have also been found in people with mild asthma. The epithelial cells that line the respiratory tract also release inflammatory mediators such as cytokines, chemokine and growth factors (8).
Monitoring the progression of asthma symptoms and controlling them appropriately is important for the future health of the respiratory system, as well as key in avoiding medical emergencies. Multiple asthma attacks can remodel the airways due to fibrosis and lead to chronic obstructive pulmonary disease (COPD). This can make the airway permanently narrower, which makes medication less effective (4). Additionally, if there is poor control over symptoms, there is a risk of a severe asthma attack, which may be life threatening.
Understanding the root
Largely, it is genetic factors that determine the development and course of asthma. Sex hormones may also play a role. In children, males that develop asthma often stop having symptoms after puberty, while females may have symptoms only in adolescents. Menopause can also trigger the onset of adulthood asthma. Additionally, adult females are more frequently hospitalised with the condition. One study found that when comparing the estradiol, progesterone, and cortisol levels of non-asthmatic people to asthmatics, those with asthma had at least one hormone outside of normal range (9).
Respiratory infections in infancy have been observed to contribute to the likelihood of developing asthma. In viral infections where a wheeze is present, though many infants will completely recover, others will maintain a wheeze that develops into asthma. The most severe childhood asthma is encountered when a lower respiratory tract infection occurs in conjunction with pre-existing sensitivities to allergens (10).
The rise in prevalence in recent years indicate that environmental factors are also involved (4).
Asthma, especially if poorly controlled, can severely affect quality of life. The sufferer may frequently feel tired, miss school or work, experience frequent lung infections, and experience stress, anxiety, and depression. In children, there may be delays to puberty or growth (2).
Signs and symptoms
Asthma can often be mistaken for a cold or a chest infection and should be investigated by a medical professional. There are tests that may exclude other pathologies. Fractional exhaled nitric oxide tests can confirm airway inflammation by the levels of nitric oxide in the breath. Spirometry may be used, which is a test to measure the how much air can be exhaled in a forceful breath, or peak flow tests may be used over a period of weeks (5).
These symptoms may indicate asthma.
- wheezing or whistling when breathing
- a feeling of tightness around the chest
- precipitated by exposure to a trigger
In persistent asthma, there is ongoing breathlessness and wheezing, while in mild asthma, there may be periods of no symptoms. Asthma is often diurnal, often worse in the mornings, although it can also be nocturnal. The cough may the most dominant symptom in some people (4).
Phytotherapy is not a replacement for emergency pharmaceutical treatment. Herbs can support respiratory health and ease mild symptoms. A prescription combining the following elements may be formulated by a herbalist in order to best address the experience of the patient.
Pulmonary tonics for long-term strengthening of the respiratory system
Expectorants – to move the excess mucus in the airways
- Lobelia (Lobelia inflata) (restricted to practitioners)
- Liquorice (Glycyrrhiza glabra)
- Gumplant (Grindelia camporum)
- Hyssop (Hyssopus officinalis)
- Thyme (Thymus vulgaris)
Antispasmodics – to relieve the constriction of the airways and ease coughing
- Pill-bearing Spurge (Euphorbia pilulifera)
- Wild Cherry (Prunus serotina)
- Coleus (Coleus forskohlii)
- Crampbark (Viburnum opulus)
Anticatarrhals – to reduce the levels of mucus in the airways
- Elderflower (Sambucus nigra) (flos)
- Plantain (Plantago lanceolata)
Antiallergenics – to reduce the allergic response that leads to symptoms
Note: Ephedra (Ephedra sinica) is a specific herb for asthma, has bronchodilatory activity. This herb is restricted, and can only be prescribed by a qualified medical herbalist in the UK.
If the asthma has specific triggers, avoiding those triggers is key to reducing symptoms. This may take some time to determine if the triggers are not easy to identify. It is often suggested to experiment with elimination of common food allergens, such as gluten, eggs, and dairy. Other common triggers are listed in above (How Does Asthma Happen).
Exercise can help build an awareness of the breath and build pulmonary health. Exercise that is also relaxing, such as yoga, qigong, and tai chi may help build a practice of regulating breath and calming the self. Exercise is often prescribed as an adjunct to asthma treatment as it improves quality of life, reduces stress, and improves breathing (6).
Physiotherapy breath retraining has also been shown to improve the quality of life with those suffering asthma. However there is a limited availability of physiotherapists trained in this specialisation, and the effectiveness of self-guided digital programmes is being investigated. Although these programmes have not been shown to improve lung function, the improvement to quality of life is significant (7).
- Wilson K, Waugh A. Ross And Wilson Anatomy And Physiology In Health And Illness. New York: Churchill Livingstone; 2010
- Asthma. NHS. https://www.nhs.uk/conditions/asthma/. Published 2021. Accessed December 28, 2021.
- Asthma UK. https://www.asthma.org.uk. Published 2021. Accessed December 28, 2021.
- Walker B, Colledge N, Penman I, Ralston S. Davidson’s Principles And Practice Of Medicine. London: Elsevier Saunders; 2014.
- Overview | Asthma: diagnosis, monitoring and chronic asthma management | Guidance | NICE. Nice.org.uk. https://www.nice.org.uk/guidance/ng80. Published 2021. Accessed December 28, 2021.
- Ding S, Zhong C. Exercise and Asthma. Adv Exp Med Biol. 2020;1228:369-380. doi:10.1007/978-981-15-1792-1_25
- Bruton A, Lee A, Yardley L, et al. Physiotherapy breathing retraining for asthma: a randomised controlled trial. Lancet Respir Med. 2018;6(1):19-28. doi:10.1016/S2213-2600(17)30474-5
- Barnes, P. J., & Drazen, J. M. Pathophysiology of asthma. Asthma and COPD. 2002; 343-359.
- Balzano, G., Fuschillo, S., Melillo, G., & Bonini, S. Asthma and sex hormones. Allergy. 2001 56(1), 13-20.
- Holt, P. G., & Sly, P. D. Viral infections and atopy in asthma pathogenesis: new rationales for asthma prevention and treatment. Nature medicine. 2012; 18(5), 726-735.