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18.3: 18.3 Cold and Allergy Medicines

  • Page ID
    177678
  • Learning Objective

    • Know the cause of the common cold and allergies.
    • Know the chemical name, common name, and uses of different cold and allergy medicines.

    The common cold (also known as nasopharyngitis, rhinopharyngitis, acute coryza, or a cold) is a viral infectious disease of the upper respiratory tract which affects primarily the nose. The symptoms of the common cold are believed to be primarily related to the immune response to the virus. Symptoms include coughing, sore throat, runny nose, and fever which usually resolve in seven to ten days, with some symptoms lasting up to three weeks. Well over 200 viruses are implicated in the cause of the common cold. The most commonly implicated virus is a rhinovirus (30–80%).

    No cure for the common cold exists, but the symptoms can be treated. Antibiotics have no effect against viral infections and thus have no effect against the viruses that cause the common cold. Due to their side effects they cause overall harm; however, they are still frequently prescribed. It is the most frequent infectious disease in humans with the average adult contracting two to three colds a year and the average child contracting between six and twelve. These infections have been with humanity since antiquity.

    An allergy is an immune response, or reaction, to substances (allergens) that are usually not harmful. In someone with allergies, the immune response is oversensitive. When it recognizes an allergen, the immune system launches a response. Chemicals such as histamines are released. These chemicals cause allergy symptoms. Histamine is concentrated in mast cells, cells whose function is essentially to release histamine and immunoglobins when tissue damage occurs. They are especially numerous in parts of the body that are injured often, such as the fingers and toes, or which enjoy frequent contact with the environment, such as the mucosa of the lips, nose, etc.

    Types of Cold and Allergy Medications

    Cold medicines are used by people with the , , or related conditions. There is, however, no good evidence that cough medications reduce coughing. While they have been used by 10% of American children in any given week, they are not recommended in Canada or the United States in children 6 years or younger because of lack of evidence showing effect and concerns of harm. One version with , , and was the 241st most prescribed medication in 2016 in the United States with more than 2 million prescriptions.

    Antihistamines are drugs that treat allergy symptoms by blocking the effects of histamines. Antihistamines come as pills, chewable tablets, capsules, and liquids.

    Two common examples of antihistamines are shown below.

    Antihistamines treat these allergy symptoms:

    • Congestion, runny nose, sneezing, or itching
    • Swelling of the nasal passages
    • Hives and other skin rashes
    • Itchy, runny eyes

    In treating diseases of allergy, the effect of antihistamines is purely palliative and confined to the suppression in varying degree of symptoms attributable to the pharmacological activity of histamine released by the antigen-antibody reaction. The drugs do not diminish the intensity of this reaction, which is the root cause of the various hypersensitivity diseases. This limitation must be clearly recognized.

    There are a number of different cold and allergy medications, which can be used to alleviate various symptoms. The commercially available products may include various combinations of any one or more of the following types of substances listed in the table below.

    Table \(\PageIndex{1}\) Different Cold and Allergy Medications.

    Medication Function Examples
    , or mucolytics a class of drugs which aid in the clearance of mucus from the airways, lungs, bronchi, and trachea , , and .
    substances claimed to make coughing easier while enhancing the production of mucus and phlegm. and .
    Antitussives, or cough suppressants substances which suppress the coughing itself substances which suppress the coughing itself , , , , and .
    for allergic rhinitis may produce mild sedation and reduce other , like and watery eyes , , , , and .
    relieve nasal congestion and sinus infection , , , and .
    or medication (antipyretic or analgesic) fever reducer or pain reliever (called "acetaminophen " in the US) and such as aspirin, or
    Syrups various substances supposed to soften the coughing honey or supplement syrup

    Effectiveness

    The efficacy of cough medication is questionable, particularly in children. A 2014 Cochrane review concluded that "There is no good evidence for or against the effectiveness of OTC medicines in acute cough". Some cough medicines may be no more effective than for acute coughs in adults, including coughs related to upper respiratory tract infections. The emphasizes that cough medicines are not designed to treat , a cough that is caused by bacteria and can last for months. No over-the-counter cough medicines have been found to be effective in cases of . They are not recommended in those who have , , or the . There is not enough evidence to make recommendations for those who have a cough and .

    Medications

    • (DXM) may be modestly effective in decreasing cough in adults with viral upper respiratory infections. However, in children it has not been found to be effective.
    • was once viewed as the "gold standard" in cough suppressants, but this position is now questioned. Some recent -controlled trials have found that it may be no better than a placebo for some causes including acute cough in children. It is thus not recommended for children. Additionally, there is no evidence that is useful in children. Similarly, a 2012 Dutch guideline does not recommend its use to treat acute cough.
    • A number of other commercially available cough treatments have not been shown to be effective in viral upper respiratory infections. These include for adults: , antihistamine-decongestant combinations, , anti asthmatic-expectorant-mucolytic combinations, expectorant-bronchodilator combinations, leukotriene inhibitors, , and , sometimes with analgesics, antipyretics, anti inflammatories, and anticholinergics - and for children: antihistamines, for clearing the nose, or combinations of these and leukotriene inhibitors for allergy and asthma. However, cannot be used as an in case of chronic, or non specific cough especially in very young children. Long term diphenhydramine use is associated with negative outcomes in older people.

    Alternative Medicine

    may be a minimally effective cough treatment. A found the evidence to recommend for or against its use in children to be weak. In light of this they found it was better than no treatment, placebo, and diphenhydramine but not better than dextromethorphan for relieving cough symptoms. Honey's use as a cough treatment has been linked on several occasions to infantile and accordingly should not be used in children less than one year old.

    Many alternative treatments are used to treat the . A 2007 review states that, "alternative therapies (i.e., , , and ) are not recommended for treating common cold symptoms; however, ... Vitamin C prophylaxis may modestly reduce the duration and severity of the common cold in the general population and may reduce the incidence of the illness in persons exposed to physical and environmental stresses." A 2014 review also found insufficient evidence for Echinacea.

    A 2009 review found that the evidence supporting the effectiveness of is mixed with respect to cough, and a 2011 concluded that zinc "administered within 24 hours of onset of symptoms reduces the duration and severity of the common cold in healthy people". A 2003 review concluded: "Clinical trial data support the value of zinc in reducing the duration and severity of symptoms of the common cold when administered within 24 hours of the onset of common cold symptoms." Zinc gel in the nose may lead to long-term or permanent loss of smell. The FDA therefore discourages its use.

    Adverse effects

    A number of accidental overdoses and well-documented adverse effects suggested caution in children. The FDA in 2015 warned that the use of codeine-containing cough medication in children may cause breathing problems. Cold syrup overdose has been linked to visual and auditory hallucinations, rapid involuntary jaw, tongue and eye movements in children.

    Cough medicines can be used as .

    Summary

    • The common cold (also known as nasopharyngitis, rhinopharyngitis, acute coryza, or a cold) is a viral infectious disease of the upper respiratory tract which affects primarily the nose. The symptoms of the common cold are believed to be primarily related to the immune response to the virus.
    • An allergy is an immune response (with the release of histamines), or reaction, to substances (allergens) that are usually not harmful.
    • A number of different cold and allergy medications can be used to alleviate various symptoms but not diminish the intensity of the response.

    Sources

    • Wikipedia
    • NIH MedlinePlus