Safety of natural products for airways

Asthma is an inflammatory disease with recurrent exacerbations. Asthma exacerbations are associated to increased inflammation of the airways; in predisposed subjects, exacerbation can be caused by respiratory infections or allergen exposition.
In case of asthma, complementary or alternative therapies are often considered. In fact, phytotherapy can be included in the therapeutic program of asthmatic chronic patients, for example, without taking the place of conventional therapies whose safety and effectiveness have been thoroughly assessed over the years and only after evaluating the risk-benefit ratio. Despite the use and use-divulgation of many plants traditionally indicated for asthma, quantity and quality of researches in this specific sector are still inadequate. Mostly of what is known regarding their effectiveness and safety is principally based on prevalence researches or on few low-quality studies reporting controversial results.¹
The major research efforts on complementary or alternative therapies for the respiratory apparatus have been focusing on Echinacea and Pelargonium’s role and possible use for cold – a well-known self-resolving condition – while on the other side they have been neglecting clinical situations like COPD and bronchial asthma, more severe and challenging from a clinical and social point of view.

Complementary and alternative therapies’ use

Contrary to the few evidences published in the literature, respiratory diseases – especially asthma and allergies – are the conditions for which patients mostly resort to complementary and alternative therapies; in particular, literature reports high consumption of plant-based therapies for asthma, both in children and adults.²
Qualitative studies show that mothers are strongly influenced by the Internet regarding asthma treatments with complementary or alternative plant-based therapies, considering them safe and free from the risk of interactions with conventional drugs.³ Actually, natural products include a variety of substances hardly manageable like plants, vitamins, minerals, supplements and botanicals: camphor, eucalyptus and menthol-based balms for the chest, aloe juice, echinacea and syrups containing tolu, wild cherry, cocillana, tea or coffee containing natural methylxanthines, or also ephedra (ma huang). These products could contain more than one medicinal plant, sometimes the wrong species, higher or lower doses of active principles than declared on the label, contaminants, adulterants, not-declared medicinal plants, pesticides or heavy metals.

Safety use

As already mentioned, labels often do not guarantee quality or coherence. Besides, natural products’ active principles are not inert and can interfere with synthesis drugs and cause undesired effects. Rare, but serious adverse reactions have been reported after using some medicinal plants. For example, liquorice, used for its anti-inflammatory and sedative action on cough – traditionally acknowledged – can prolong corticosteroids’ hemi life potentiating their cardiovascular effects and reducing their hepatic catabolism. Or ephedra, a Chinese traditional medicinal plant used as decongestant in bronchial asthma treatment and containing ephedrine (a sympathomimetic amines), can induce cardiovascular effects especially if administered in concomitance with albuterol. Ephedra use is nowadays widely considered out-dated for its frequent cardiovascular side effects and the availability of selective adrenergic agents.
Many apparently harmless products can actually be allergenic. For example, echinacea and chamomile, plants belonging to the family of composite, can worsen asthma in patients who are sensitive to these species antigens.
Extremely worrying are in the end reports regarding the treatment modality of these products. A small number of subjects, in fact, reported ingesting camphor-base products. Ingestion of turpentine oil and Vicks vaporub® can be fatal in children and put a risk for adults too.⁴
The use of these products can be associated to a reduced inhaled corticosteroids adherence, as well as conventional therapies substitution (especially short-acting beta-agonists and inhaled corticosteroids).
Substituting conventional drugs with complementary and alternative therapies can delay prompt and appropriate medical intervention in case of acute asthma episodes or diminish the adherence to evidence-based conventional treatments, therefore contributing to increased morbility.⁵

Conclusions

Considering the current state of research, scientific evidences, treatment modalities and safety and effectiveness studies are still largely needed, both for clinicians who treat patients with asthma and for patients opting for self-medication. A good physician-patient communication on complementary or alternative therapies is also missing, also because few clinicians are informed about their use and patients often are reluctant to declare it.