Allergies, Eczema, Hay fever and Asthma

   

Posted: September 2024

Author: Phil Rasmussen | M.Pharm., M.P.S., Dip. Herb. Med.; M.N.I.M.H.(UK), F.N.Z.A.M.H.
 

Allergies – Eczema, Hay fever and Asthma

One of the important roles of an immune system is to protect us against pathogenic microbes and other unwanted compounds, in our diet, airways or on our skin. Frequently though, our physiological responses to certain allergens become excessive and potentially harmful reactions occur. Atopy is a genetic tendency to develop allergic diseases, mediated by antibodies attaching to mast cells to release inflammatory mediators such as histamine, TNF-α, interleukins and other cytokines ⁽¹⁾. Dysbiosis is another factor contributing to the development of atopic diseases ⁽²⁾. Worringly, the global prevalence of atopy and allergic conditions has increased substantially in recent decades ⁽³⁾.

The three most common types of allergies (atopic diseases) include eczema, allergic rhinitis (hay fever) and allergic asthma. A strong familial association exists, with at least 35% of asthma patients having a parent with the same diagnosis ⁽⁴⁾. Atopic diseases can often progress, with eczema being the first to manifest. This is followed by food allergy and then allergic rhinitis or allergic asthma, a sequence known as the allergic march ⁽⁵⁾.

Disruption of the epithelial barrier may be an initial step in initiation of an inflammatory allergic pathway (the epithelial barrier hypothesis), and both genetic and environmental factors can mediate this. Dietary factors as well as air quality are important considerations when determining treatments for atopic conditions. An anti-inflammatory diet rich in pulses, vegetables and fruit, was associated with a lower prevalence of asthma but not allergic rhinitis or eczema, in a recent Greek study ⁽⁶⁾.

Eczema

Eczema (atopic dermatitis) is a skin disease characterised by skin barrier dysfunction and inflammation. This is due to various factors including genetics, immune system dysregulation, and environmental triggers.

It is a common dermatological condition seen by medical herbalists in Aotearoa New Zealand. Treatment depends on type and history, particularly factors such as its duration, whether other treatments such as steroid creams or other medications are currently being used, and what treatments the patient has previously tried.

Numerous backgrounds and potentially contributory factors are involved in the aetiology of eczema, though trying to identify these can be challenging. Therefore, a thorough case history is important and an individualised herbal treatment regimen, is crucial.

Aetiological triggers can include both internal and external factors, with possible contributions from the hormonal or nervous system, and of course the gastrointestinal system and its microbiota as well as that of the skin. Incorporation of probiotics and prebiotics into the daily routine can help enhance the skin barrier ⁽⁷⁾.

The use of different cosmetics, soaps, detergents, work-related solvents, or medications should be determined. Eczema is the most common adverse event to many drugs including antibiotics, and occasionally also, to plants taken as foods or medicines.

Patients who have been using strong steroid or other topical agents for prolonged periods, can take a while to respond to phytotherapy treatment. Therefore, a gentle and persistent approach, supported using antipruritic and soothing lotions or infusions applied frequently throughout the day, will often pay dividends. Topical anti-inflammatory herbs such as Burdock, Chamomile, Comfrey and Liquorice, can provide symptomatic relief of pruritis and pain.

Many NZ natives can help with eczema treatment, particularly when applied topically. These include Akeake, Kānuka, Kawakawa, Poroporo, Mānuka, Kumerahou, Hoheria and Tanekaha. Each of these herbs are indicated for use depending upon the type of eczema, and whether the skin is broken or not. Tannin-rich plants tend to be best for more open and acute forms of eczema, and where there is an element of weepiness, or raw skin exposed.

Sarsaparilla (Smilax spp) has long been used as an overall tonic, to ‘purify the blood’ and to treat skin conditions such as eczema and psoriasis. While little published research on its application in dermatology exists, anti-inflammatory properties, and protection against environmental toxins such as lead, have been reported ^{(8, 9)}. It has also been shown to suppress house dust mite-induced atopic dermatitis in mice ⁽¹⁰⁾.

Numerous other phytomedicines have potential applications as internal treatments for eczema, including Burdock (Arctium lappa), Dandelion (Taraxacum officinale), Figwort (Scropularia nodosa), Violet (Viola odorata), Rehmannia (Rehmannia glutinosa), Baical Skullcap (Scutellaria baicalensis) and Chamomile (Matricaria recutita).

Stress can of course have a major influence in some patients, and incorporation of phytomedicines with an adaptogenic or anxiolytic action, is often called for with atopic patients.

Asthma

Rates of asthma in Aotearoa New Zealand are higher than those in many other countries ⁽¹¹⁾. Around 10% of New Zealanders have asthma, with a higher prevalence in Māori.

Allergic (atopic) asthma is chronic, reversible bronchoconstriction influenced by an allergic trigger, leading to symptoms of cough, wheeziness, shortness of breath, and tightness in the chest. While a heterogeneous condition with many genetic, environmental, cellular, and molecular aetiological influences, our high seasonal pollen count and use of agricultural sprays, are likely contributory ⁽¹²⁾. Rising temperatures and extreme weather events also increase our exposure to allergens, mould, and air pollutants ⁽¹³⁾.

Allergic asthma is triggered by allergens such as pollen, pets and dust mites, as well as a wide range of other triggers including cold weather and smoke. Recent animal studies have reported exacerbation in allergic asthma by plastic pollution derivates, such as polystyrene microplastics and dibutyl phthalate. This produce increased reactive oxygen species in the lungs leading to eosinophilic inflammation and an inflammatory response mediated by the NF kappa B pathway, and increased hypersensitivity through increased IL-4 production ⁽¹⁴⁾.

Treatment depends upon the patient’s age, symptoms, clinical history and whether concomitant drugs are being taken. Asthma is a serious condition, and most patients are prescribed bronchodilators such as salbutamol, formoterol, or albuterol, which act as β-adrenoceptor agonists, often combined with steroid anti-inflammatory drugs such as budesonide. Given the life-threatening nature of a sudden and serious asthma attack unless appropriate treatment is given promptly, natural health practitioners need to ensure they do not give advice concerning these medications that is outside of their scope of practice.

Respiratory bacterial and viral infections contribute to exacerbations of asthma symptoms, and Elecampane (Inula helenium) has long been applied to treat lung conditions including tuberculosis, cancer and asthma. The ethanol extract of the root has anti-inflammatory properties, and isoalantolactone and other sesquiterpene lactones it contains can alleviate acute lung injury through anti-inflammatory and other protective activities. Mechanisms include through activation of Nrf2⁽¹⁵⁾, and inhibition of TRAF6, (TNF receptor associated factor 6) an upstream transcription factor of NF-kappa B ⁽¹⁶⁾. The strong antibacterial activities of Elecampane ⁽¹⁷⁾ can also help prevent or treat lung infections that sometimes trigger an asthma attack, particularly in immune compromised individuals.

Bupluerum (Bupleurum falcatum) is another phytomedicine often useful in the treatment of asthma, with its all-round adaptogenic and protective actions on the lungs. Its saikosaponin constituents exhibit pronounced anti-inflammatory and anti-allergic activities, including inactivation of the NF-kappa B signalling pathway ^{(18, 19)}.

Bacopa (Bacopa monnieri) exhibits anxiolytic and anti-inflammatory actions within the central nervous system. This can help in the management of asthma patients where stress and anxiety seem contributory. A bronchodilatory action has also been reported for Bacopa in rats, with activation of β-adrenoceptors implicated as a mechanism ⁽²⁰⁾.

One of the best medicinal plants for asthma patients here in Aotearoa New Zealand, is Kumerahou (Pomaderris kumerahou). Kumerahou is well known for the treatment of chest infections and coughs and was once widely used to treat tuberculosis. Its use to treat asthma became popular in the 1930s. Rich in anti-inflammatory saponins, it also has a history of use for skin conditions including eczema. As with many medicinal plants used for such skin conditions, this treatment can be both internally and topically.

Hay fever

Allergic rhinitis (hay fever) is an atopic disease characterised by nasal congestion, clear rhinorrhea, sneezing, postnasal drip, and nasal itchiness. It is an immune response mediated by IgE antibodies against inhaled antigens in the initial phase, followed by a subsequent phase mediated largely by leukotrienes. Around one in five New Zealanders are affected by it, and it can be chronic or seasonal, the latter being more common in children and young adults.

Conventional treatment for allergic rhinitis consists of antihistamines and nasal steroids, although long-term use of these is associated with various adverse events. The recent rescheduling of pseudoephedrine, will lead to more of this symptomatic decongestant being used, but as with other decongestant drugs such as oxymetazoline, rebound congestion can occur once these are discontinued.

Many phytomedicines can provide symptomatic relief to hay fever patients however, without the same predisposition to adverse effects. These have multiple mechanisms of action but include modulation of cytokine signalling and the immune response, as well as a range of anti-inflammatory effects. Some herbs regulate the inflammatory response to antigenic stimuli, while others probably through their bitter taste, can help invoke a more moderate bodily response to antigen processing, through NF-kappa B signalling ⁽²¹⁾.

Decongestant properties that are generally milder but not dissimilar to those of drugs such as pseudoephedrine, can be achieved with reasonable doses of Elderflower (Sambucus nigra) and Peppermint (Mentha piperita). Elderflowers are rich in anti-inflammatory flavonoids including rutin and quercetin, and phenolic acids which help remove mucus and fluid from the nasal passages. Menthol and other volatile oil constituents, rosmarinic acid and flavonoids in peppermint leaves, stimulate the microvasculature to produce similar effects ⁽²²⁾. The antimicrobial and antiviral properties of each, can also support recovery from a sinus infection, or prevent development of these secondary consequences of rhinitis.

Another excellent mucous membrane trophorestorative is Ribwort (Plantago lanceolata), particularly suitable and often recommendable for long-term use. Ribwort leaves are rich in chlorogenic acid, quercetin, rutin and other anti-inflammatory flavonoids. They are used in many herbal medicine traditions for respiratory tract conditions including allergic rhinitis, chest infections, coughs, and sometimes allergic asthma ^(2,3). A relaxant effect on rat tracheal smooth muscles, has been reported for a hydroethanolic extract of the closely related Plantain (Plantago major) ⁽²⁴⁾. Potent antibacterial activities for root extracts, have also recently been reported ⁽²⁵⁾.

Baical Skullcap (Scutellaria baicalensis) is a popular medicinal plant in Traditional Chinese Medicine for the treatment of allergic rhinitis, eczema, and sometimes asthma. Anti-inflammatory and antimicrobial properties have been documented in numerous studies for Baical skullcap and its flavonoid constituents, including inhibition of chemokine, cytokine, and other inflammatory mediators ⁽²⁶⁾. An ethanol extract has been reported to alleviate allergic airway inflammation and suppress mast cell degranulation and histamine release ⁽¹⁸⁾. Recent studies have also revealed several modulatory actions on the gut and respiratory microbiota ^{(27, 28)}.

Rehmannia (Rehmannia glutinosa) is another Chinese medicinal plant widely used to treat allergic conditions. Large doses can produce rapid symptomatic relief for pruritic inflammatory skin conditions, and moderate doses are commonly given longer term for a wide range of autoimmune conditions. Rehmannia is a popular component of traditional Chinese formulations used for centuries to treat allergic asthma, and inhibits inflammatory cell infiltration into the airways, as well as airway remodelling in asthma ^{(29, 30)}.

Our native Horopito (Pseudowintera colorata), can also benefit patients with hay fever or asthma ⁽³¹⁾. Anti-allergic and anti-anaphylactic properties for a key sesquiterpene constituent polygodial have been reported in animal studies, involving prostaglandin E2, bradykinin, substance P and histamine ^{(32, 33)}.

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