The common cold and flu are both upper respiratory tract illnesses caused by viral infections. They both tend to be acute, self-limiting and may sometimes involve the lower respiratory tract. Both the common cold and flu are contagious respiratory illnesses but are caused by different viruses; flu is caused by different influenza viruses and the common cold can be caused by coronaviruses, rhinoviruses, adenoviruses and parainfluenza viruses. The incidence of the common cold and flu is subject to seasonal variation, with a higher incidence in winter compared to summer. The common cold is the most common illness in the world, with an average of 6-8 episodes per year in children, decreasing to 2-4 episodes per year in adults. It can have a large economic burden due to absenteeism at work and school.
The common cold and flu can share some similarities in symptoms but differences exist between the viruses. The common cold generally has a gradual onset of symptoms, compared to the more sudden onset of flu symptoms, which usually appear within a few hours. Both viruses can be unpredictable, but symptoms generally start to resolve after one week. Symptoms of cold are usually limited to the upper respiratory tract (nose and throat) and flu symptoms generally affect more than just the upper respiratory tract, with symptoms of flu usually much more severe than those of a cold. Symptoms of a cold can include blocked or runny nose, sneezing, cough, sore throat and fever. Symptoms of flu can include fever, fatigue, body aches, headache, difficulty sleeping, loss of appetite, dry cough and nausea. Runny nose and sore throat are also possible, but less common than with the common cold. Influenza can be classified into uncomplicated and complicated.
Uncomplicated flu is characterised by the sudden onset of the typical symptoms outlined above, with symptoms generally resolving in less than two weeks. Complicated flu occurs when the viral infection causes a potential wide range of complications that can result in severe disease.
Complications and Warning Signs
The common cold and flu are generally self-limiting in healthy individuals and usually will resolve within two weeks. However, flu and complications of flu can lead to serious illness. In children, otitis media (middle ear infection) and respiratory complications including croup and bronchiolitis are most common. Rarer complications in children can include myocarditis, pericarditis, encephalopathy, encephalitis and Reye’s syndrome. The most common complications of flu in adults are pneumonia and bronchitis, which can lead to respiratory failure, acute
respiratory distress syndrome, septic shock or multi-organ failure. Flu can often cause dehydration, which can exacerbate underlying chronic medical conditions. Patients that are aged 65 years or older, pregnant or have a long-term medical condition are at an increased risk of complications from flu. As patients with asthma, COPD, diabetes and heart failure are at a higher risk of complications, there may be a need to refer to a medical doctor for further treatment. Pharmacists and pharmacy staff should be aware that patients may need referral to a doctor if their symptoms don’t improve after 7 days or they have a weakened immune system, due to HIV or chemotherapy.
In the event of patients experiencing any warning sign symptoms, then they should seek medical attention immediately. Pharmacies are often the first port of call for patients with symptoms, therefore pharmacists and
pharmacy staff should recognise when referral is necessary. Some of the more common of these warning signs are outlined in the table below.
Community Pharmacy Role in Cold and Flu
Community pharmacy is often the first port of call for patients when they have symptoms of cold or flu. Most symptoms can be effectively treated by using over the counter (OTC) medicines from community pharmacies, which can help reduce the burden on other primary care providers and emergency departments. A systematic approach to each consultation should be implemented to ensure a consistent high-level of care to each patient presenting with cold and flu symptoms. A patientcentred approach should be followed in community pharmacy. All pharmacy staff should be fully trained and competent in conducting OTC consultations. There is a great importance in tailoring each consultation to reflect the different role, responsibility and knowledge of the staff members. Pharmacy staff should know when to refer to the pharmacist when carrying out each consultation.
Effective consultations between pharmacy staff and patients are fundamental to ensure appropriate recommendations are made and desired patient outcomes are achieved. Optimal management of these consultations require effective information gathering from the patient, with proper use of a framework essential for retrieving information. Who is the patient, What are the symptoms, How long has the patient had the symptoms, Action to date and other existing Medication being taken (WWHAM) is the most common framework used in information gathering. Effective communication skills are necessary to counsel each patient and communication style may be required to be tailored to each patient. Pharmacists should oversee consultations to ensure correct treatment options are selected or patients are referred if necessary.
Prevention
Prevention is key in reducing the burden of cold and flu in society. Pharmacists are trusted healthcare professionals and therefore can reshape patient perceptions and reinforce the messaging around prevention of infection. Vaccination is an important preventative measure against influenza. Unfortunately, due to many different serotypes of the common cold, it is not possible to vaccinate against this illness. Simple measures including
regular handwashing with soap, avoiding touching the face and cleaning surfaces that people regularly touch can help prevent spread of respiratory viruses. Covering coughs and sneezes with a tissue and discarding the tissue immediately after use, improving ventilation in buildings and avoiding close contact with other people when symptomatic are all also practical measures that patients can be counselled on to reduce spread of common cold and flu.
Vaccination
Vaccination is the best method of protection against flu. Vaccines contain weakened or inactive parts of a pathogen that triggers an immune response in the body, that will produce antibodies and offer protection if exposed to the pathogen later. The flu vaccine should be administered annually as the antibodies reduce over time, as well as the fact that flu strains can change from year to year. The vaccine is generally available from October to April, but it is ideal to get it as early as possible, before the commencement of flu season. Vaccination generally reduces the risk of getting flu by 40% to 60% and can also reduce intensity and duration of symptoms.
There are usually two vaccines available in Ireland; the quadrivalent influenza vaccine (QIV) which is generally used for over 18 years old and the live attenuated influenza vaccine (LAIV) which is used for those aged 2 to 17 years old. The preferred administration site for the QIV is in the deltoid muscle via intramuscular injection. The LAIV is administered nasally, with half of the dose administered via a spray in both nostrils. Mild side effects are possible and can include fever, fatigue, soreness or swelling at injection site, body aches and headaches. Nasal congestion is also common with nasal administration of the vaccine. These are generally self-limiting and will resolve within 48 hours. Taking paracetamol and resting are advised if these side effects are experienced. More serious side effects are rare and should be reported to the HPRA.
Pharmacists have been providing a seasonal influenza vaccination service in community pharmacies since 2011. Flu vaccination service in community pharmacies has been reported to improve uptake of the vaccine. Recommendations from healthcare workers have also shown to greatly improve
vaccination rates. As patients visit their community pharmacy much more often than their primary care physician, pharmacists have a very important role in this. Pharmacist can counsel patients on the benefits of vaccination, risks of not getting vaccinated and ease patient concerns regarding potential side effects.
Diagnosis
The diagnosis of common cold and flu is generally based on symptoms and physical examination. As these illnesses are usually self-limiting, symptoms can be examined by a physician and a diagnosis made without need for further diagnostic tools. Rapid influenza diagnostic tests (RIDTs) can be used to diagnose influenza by detecting antigens that stimulate an immune response. Molecular assays that detect genetic material of influenza can be used and are more accurate than RIDTs. Both tests take less than 20 minutes to perform. Specialised laboratory tests such as polymerase chain reaction (PCR) tests can be used for diagnosing influenza. These tests are usually not required but can be useful in differential diagnosis between common cold, influenza and other respiratory infections including Covid-19. Reliability can be an issue for all these methods of diagnosing. Therefore, diagnostic tools are not very useful, and treatment can be initiated if required based on clinical symptoms, patient history and physical examination.
Treatment
Treating based on symptoms that a patient exhibits is the mainstay of treating common cold and flu. Getting a full knowledge of clinical symptoms and patient history is important in selecting an appropriate treatment option. OTC analgesic options including paracetamol and ibuprofen are useful in treating aches and pains, as well as lowering fever associated with the viral infection.
Antihistamines
First-generation antihistamines such as brompheniramine and chlorpheniramine have been shown to provide some symptomatic relief. This involves a reduction in symptoms such as sneezing and nasal discharge, as well as a reducing the duration of symptoms. Side effects associated with diphenhydramine include drowsiness, dry mouth and blurred vision. Second-generation antihistamines are ineffective in treating symptoms of cold and flu.
Decongestants
Decongestants have been shown to have clinical effectiveness in reducing symptoms of rhinorrhoea, nasal congestion and sneezing. Pseudoephedrine and Phenylephrine are two decongestants that are licensed for OTC use in those aged 12 years and older in Ireland. Potential side effects can include agitation, hypertension, tachycardia, nausea and dysrhythmia. Decongestants can also be used in combination with a first-generation oral antihistamine. Xylometazoline is a decongestant that can be used topically to reduce nasal symptoms. Side effects of nasal decongestants can include irritation of nasal membranes, rebound congestion and nosebleeds.
Non-pharmacological treatment
Daily administration of zinc has effectiveness in reducing the number of colds per year, particularly in children. Other supplements such as vitamin C, vitamin D and garlic have mixed results, with studies showing no benefit versus placebo. Natural products including ginseng and echinacea showed no clear evidence of benefit. Homeopathy also does not have a positive effect on preventing or treating the common cold or flu. Honey may be useful in treating nighttime cough in children but should not be used in children under 12 months due to the risk of infant botulism. Bulb suction with saline drops can be useful in relieving nasal symptoms in children. Vapour rub containing ingredients such as eucalyptus, camphor and levomenthol may provide symptomatic relief in children over 2 years old.
Pharmacists and pharmacy staff should carry out a structured approach to each consultation to ensure each patient receives appropriate counselling, treatment and referral if necessary. Prevention is important in reducing the spread of flu, with vaccination the best approach in preventing and reducing severity of symptoms. Hand hygiene and other measures can also be effective in reducing transmission of respiratory viruses. The diagnosis of cold and flu is generally based on symptoms and physical examination, with laboratory tests used only if necessary. Antibiotics are not effective in treating cold and flu, and their use can lead to the development of antimicrobial resistance.
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