Non-Pharmacological Remedies for Post-Viral Acute Cough

Post-viral acute cough (PAC, post-viral acute cough – PAC) is a common symptom associated with acute upper respiratory tract infection. It is particularly common in children and adolescents. Upper respiratory tract infections (URTIs) are a term encompassing a range of acute diseases of the upper respiratory tract that depend on the following location of the source of inflammation:

• nasal cavity;
• paranasal sinuses;
• ears;
• throat;
• larynx;
• trachea.

The following forms of URTI are distinguished:

• acute nasopharyngitis/rhinopharyngitis;
• acute pharyngitis;
• acute sinusitis;
• acute tonsillitis;
• acute otitis media;
• acute laryngitis;
• acute epiglottitis;
• acute tracheitis.

The most common form is acute rhinopharyngitis, which presents with the following symptoms:

• cough;
• sneezing;
• rhinorrhea;
• nasal congestion;
• hypo/anosmia (loss of smell);
• hypo/ageusia (reduced or absent sense of taste);
• sore throat;
• headache;
• pressure in the facial region of the skull;
• myalgia;
• low-grade fever.

Cough, as the main symptom of URTI, is primarily a protective reflex that clears the airways of excess secretions. Acute cough is the main reason patients seek primary care. The etiological cause of URTI is most often a viral infection. Symptoms of an acute viral infection generally last less than 10 days. Cough usually lasts up to four weeks.

The arsenal of cough remedies is extensive, as physicians prescribe cough medicines as first-line treatment. A substantial share of the market consists of over-the-counter cough medicines, which have different mechanisms of action (Morice AH et al. Over-the-counter cough medicines. Pulm Pharmacol Therap 2015):

• antitussives;
• expectorants;
• mucolytics;
• antihistamines;
• decongestants.

Until recently, there was no convincing evidence for or against over-the-counter formulations, and the available meta-analysis data were heterogeneous and imprecise. The authors of the article “Non-pharmacological remedies for post-viral acute cough” (Giorgio Cipran et al), published in 2022 in “Monaldi Archives for Chest Diseas”, conducted a thorough analysis of the over-the-counter cough-remedy market and presented detailed data. It should be noted that many components of non-pharmacological preparations belong to traditional Western medicine and have a history of use extending for more than a thousand years. Despite this, few substances are supported by scientific data obtained in randomized controlled trials.

More relevant information is available via LINK 

Let us consider the arsenal of over-the-counter cough formulations.

Non-pharmacological antitussive compounds comprise the following groups:

• nutrients (honey and its derivatives);
• plant-derived substances (glycerin, hyaluronic acid, balsamic substances);
• aqueous solutions;
• extracts.

HONEY AND ITS DERIVATIVES

Honey is a product produced by bees (Apis mellifera) from nectar or honeydew. Chemically, honey is a supersaturated sugar solution. Because of their viscosity, saccharides adhere to irritated mucous membranes, creating a protective film and maintaining hydration. Accordingly, this provides a soothing effect on cough. In addition, honey has anti-inflammatory, antioxidant, antibacterial, and metabolic activity.

The World Health Organization (WHO) currently recommends honey as an inexpensive and safe remedy for PAC.

PROPOLIS

Propolis is a resinous mixture produced by honeybees: a product formed by mixing saliva, beeswax, and exudate from tree buds. It has bactericidal and disinfectant effects. It modulates the immune response. It is used for upper respiratory tract infections.

PLANT-DERIVED SUBSTANCES

GLYCERIN

Glycerin is a colorless, odorless liquid. It is naturally present in all cells in the form of triglycerides. Because of its moisturizing and emollient properties, as well as its sweetness, it is included in cough syrups. It binds water molecules and has a plasticizing effect, which prevents drying of the mucous membrane.

MENTHOL

Menthol is an organic substance isolated from peppermint essential oil or produced synthetically. It is a cyclic monoterpene alcohol. It is present in many cough remedies. It has local anesthetic, antifungal, antipruritic, anti-inflammatory, antitussive, antiviral, and insecticidal effects.

EUCALYPTOL

Eucalyptol, or cineole, is a monocyclic terpene. It occurs naturally in the essential oils of eucalyptus leaves, wormwood, rue, sage, and peppermint. It has anti-inflammatory and antioxidant activity. It acts on TLR (Toll-like receptor) receptors — cellular receptors that recognize microbial structures and activate the cellular immune response.

THYMOL

Thymol is a monoterpene phenol. It is found in the essential oils of the leaves and seeds of common thyme. It has antioxidant, anti-inflammatory, local anesthetic, and antiseptic effects.

MYRRH

Myrrh is a natural resin from the Commiphora plant. It is rich in tannins, polysaccharides, and flavonoids. It has analgesic and antitussive effects.

RESVERATROL

Resveratrol is a polyphenol and natural phytoalexin. It is found in grape skins and in red and white wine. It has anti-inflammatory, antioxidant, and antiviral properties.

HYALURONIC ACID (HA)

Hyaluronic acid is a major component of the extracellular matrix and is present in respiratory tract secretions. HA is a highly hygroscopic molecule, allowing it to modulate osmotic balance. The main functions of HA are:

• hydrating (moisturizing the respiratory tract mucosa);
• restorative (soothing and restoring the respiratory tract mucosa);
• protective (maintaining the protective barrier against environmental agents);
• immunological (interaction with CD44 receptors [hyaluronic acid receptors] involved in mechanisms of adhesion and migration of inflammatory cells; modelling of kallikrein-1 activity [a group of blood proteins involved in inflammatory processes]).

Hyaluronic acid is widely used in nasal sprays.

AQUEOUS SOLUTIONS

SALINE SOLUTION

Hypersecretion of mucus in the upper respiratory tract causes posterior rhinorrhea, which in turn provokes postnasal drainage of secretions with receptor irritation and consequently triggers the cough reflex. Nasal saline spray in isotonic or hypertonic form is widely used in patients with upper respiratory tract infections (Shaikh N et al «Decongestants, antihistamines and nasal irrigation for acute sinusitis in children.» Cochrane Database Syst Rev 2010). In addition, nasal irrigation and humidification are among the fastest and safest methods for infants.

Saline solution can also often be combined with active components such as hyaluronic acid and/or plant extracts, producing a synergistic effect.

PLANT EXTRACTS

• Adhatoda vasica (Justicia adhatoda);
• American agave (Agava americana);
• aloe vera (Aloe vera);
• marshmallow root (Althea officinalis);
• Iceland moss/Iceland lichen (Cetraria islandica);
• citrus fruits/grapefruit (Ciitrus paradisi)/mandarin (Citrus reticulata);
• round-leaved sundew/sundew (Drosera rotundifolia);
• purple echinacea (Echinacea purpurea);
• eucalyptus (Eucaliptus globulus);
• licorice (Glycyrrhiza glabra);
• Grindelia robusta (Grindelia robusta);
• common ivy (Hamamelis virginiana);
• hedera helix;
• immortelle (Helichrysum italicum);
• helix pomatia/helix aspersa;
• wild mallow (Malva sylvestris);
• common horehound (Marrubium vulgare);
• peppermint (Mentha piperita);
• Myroxylon balsamum (Myroxylon balsamum);
• common poppy (Papaver rhoeas);
• Pelargonium sidoides (Pelargonium sidoides);
• mountain pine (Pinus mugo);
• broadleaf plantain (Plantago major);
• polygala (Polygala);
• black poplar (Populus nigra);
• black currant (Ribes nigrum);
• rosehip (Rosa canina);
• common sage (Salvia officinalis);
• elder/black elder (Sambucus nigra);
• thyme (Thymus vulgaris);
• linden/large-leaved linden (Tilia platyphyllos);
• Uncaria tomentosa (Uncaria tomentosa).

The list presented above includes only those plant extracts whose effectiveness has been documented.

Additional facts on related topics are available via LINK

Sufficient data have accumulated to indicate that some non-pharmacological substances significantly improve post-viral acute cough and reduce cold symptoms. These data support the popular tradition of using natural compounds to relieve cough and cold symptoms. However, many natural components remain insufficiently studied. Further research is needed for a deeper understanding and scientific confirmation of the use of non-pharmacological formulations.

References:

Morice AH et al. Over-the-counter cough medicines. Pulm Pharmacol Therap 2015

Shaikh N et al «Decongestants, antihistamines and nasal irrigation for acute sinusitis in children.» Cochrane Database Syst Rev 2010