What is the common cold?

The majority of the population suffer two to three colds every year (children as many as eight) and we are all familiar with the symptoms which include sneezing, a blocked or runny nose, sore throat, headache, lack of energy and raised temperature. Despite the ubiquity and prevalence of the common cold there is surprisingly little research published on the condition. This is perhaps due to the fact that it is a self-limiting illness and rarely fatal but nevertheless has a significant financial burden through loss of productivity and absence from education and the workplace.

Although named the common cold and despite more occurring in the winter months it is not the cold weather per se that accounts for the increased incidence at these times of year.  The viruses causing the common cold are spread by droplets in the air and hand to hand contact. People spend more time inside in the winter with less ventilation so transmission of the viruses is more likely.

A number of other terms are sometimes used to describe the common cold including:

·       Head cold

·       Upper respiratory tract infection

·       Acute coryza

·       Nasopharyngitis

·       Rhinopharyngitis

·       Flu – an incorrect use, see below

 

What causes the common cold?

The common cold is caused by many different viruses and is the reason why antibiotics will not treat the common cold. About half of common colds are caused by rhinoviruses of which there are over a 100. The other common cold viruses are coronaviruses, influenza and parainfluenza viruses, respiratory syncytial virus (RSV) and metapneumovirus. After infection with one virus immunity will be developed  but because there are so many viruses and that they mutate further colds can be caught in the same season.

 

What actually happens to the body in a cold?

The viruses enter the body via the mucous membranes of the nose, mouth or eyes. The viruses enter the epithelial cells that line these membranes and then begin to replicate. The innate (non-specific) part of the immune system is triggered. This is largely an acute inflammation releasing chemicals (including prostaglandins and bradykinin) and the white blood cells called neutrophils. Pelargonium extract has been shown to prevent viruses entering our cells.

Blood flow in the area is increased and the blood vessels become leaky, so the tissues swell with the extra fluid (oedema). Increased mucus production leads to nasal discharge. The inflammatory chemicals also increase the sensitivity of the nerve endings which can cause sneezing.

These inflammatory chemicals circulating in the body give rise to other symptoms including increase in temperature, headaches, muscle aches and malaise (general unwell feeling).

Next the specific (adaptive) immune system takes over. Cells known as dendritic cells or antigen presenting cells process the viral proteins and present them to the body’s T-cells. The T-cells are white blood cells also known as lymphocytes that mature in the thymus (hence the T) that are key players in coordinating the body’s immune response to infections and cancer. Small numbers of them remain after the infection has cleared to help mount a faster response if the same virus is encountered again (known as memory T-cells).

The T-cells also activate another white blood cell (lymphocyte), the B-cells, to make antibodies against the virus. A small number of these also remain as memory B-cells to respond more rapidly when the virus is next encountered.

Much of the immune system control takes place in the lymph nodes which are distributed around the body and why these often become enlarged and tender when an infection is present. Pelargonium extract has been shown to stimulate a number of cells involved in the innate and specific immune responses.

 

Could I have something other than a common cold?

The symptoms of the common cold may include any or all of the following:

·        Blocked or runny nose

·        Sneezing

·       Sore throat

·        Cough

·        Headache

·        Generally feeling unwell (malaise)

·        Fever

Some, or all of these symptoms can be a manifestation of other conditions. Key signs and symptoms to look out for to suggest you have more than the common cold are:

·       A significantly increased temperature (over 38° C/100.4° F) is more likely to be influenza (flu) especially if it began suddenly with fever and /or chills and severe muscle aches.

·       COVID-19 symptoms can be very similar to the common cold, but a higher fever, muscle aches and loss of taste or smell are more likely with COVID.

·       Sneezing with a runny nose (rhinitis) that has been present for over 14 days could be allergic rhinitis especially in warmer weather conditions which could be hay fever.

·       Chest pain, especially on breathing, coughing or sneezing with cold symptoms could indicate pneumonia.

·       Enlarged red tonsils are often seen with the common cold but if there is yellow or green pus on them it could be group A streptococcal tonsillitis (a bacterial infection) especially in children. Unlike the viral cold, tonsillitis might require antibiotics. Doctors use the Centor criteria to help decide if antibiotics are required.

If you ever have more than the classic cold symptoms then you should consult with a health care professional.

 

What treatments can be recommended for the common cold?

There is no cure. It is self-limiting and symptoms typically last a week to 10 days. The over the counter cold and flu market is huge and many people have their favourites. They are all aimed at symptom relief.

Paracetamol

Paracetamol, known as acetaminophen in the USA and Japan, can be used to help with pain and fever. It is one of the most commonly used agents. Many proprietary cold and flu remedies contain paracetamol combined with a decongestant or antihistamine. Always check the label of such remedies before taking additional paracetamol tablets.

Non-steroidal anti-inflammatory drugs (NSAIDs)

These include aspirin and ibuprofen which can be taken to relieve the pain and fever of the common cold. These drugs must be avoided in those with gastric issues such as reflux or stomach ulcers and some asthmatics. Aspirin must not be given to children under the age of 16 years because of the risk of Reye’s syndrome.

Over the counter cold remedies

Many formulations containing decongestants and/or antihistamines often combined with paracetamol.  Decongestants work by causing constriction of the blood vessels in the nose. Oxymetazoline is s commonly used decongestant which can be used for a maximum of seven days because longer use may cause rebound nasal congestion when eventually stopped.

Pseudoephedrine and is still available as a pharmacy only medicine but they can be associated with the rare and potentially life-threatening complications of posterior reversible encephalopathy (PRES) and reversible cerebral vasoconstrictor syndrome (RCVS).

Honey

In studies honey was shown to be more effective to relieve cough than no treatment, placebo or diphenhydramine (an antihistamine).

Pholcodine

All medications containing pholcodine have been withdrawn from the market in the UK and Europe. It was used to treat cough (anti-tussive) but a risk of serious allergy (anaphylaxis) to neuromuscular blocking agents used in general anaesthesia was identified in those who had used pholcodine in the last 12 months.

Antibiotics

Antibiotics only work against bacteria not viruses. The common cold and it’s associated symptoms are caused by viruses so antibiotics will not work.

Indeed, taking antibiotic inappropriately may cause more harm both to the individual in the form of side effects (nausea, diarrhoea, allergy) and to the population as a whole in the form of antibiotic resistance.

Pelargonium

Pelargonium sidoides and/or Pelargonium renifome root extract has been licensed under the traditional herbal registration scheme in the UK for the symptomatic relief of upper respiratory tract symptoms. It has been used for over a 100 years in South Africa. Laboratory (in vitro) research has shown that it prevents viruses from entering our cells and enhances the body’s immune response to help fight infections.

 

What about preventing the common cold?

Primary prevention including measures such as regular washing of hands and avoiding touching the mouth, nose and eyes with the fingers can help prevent you from ingesting viruses found on surfaces.

Physical activity, exercise and diet are important in helping to maintain health and prevent diseases including diabetes, cardiovascular disease and some cancers. Regular exercise does not prevent the common cold but does reduce the severity and duration of the illness.

Similar to the cold remedy market, there are many supplements available with the promise of preventing the common cold.

Zinc

The mineral zinc is one of the most important in the human body and is the second most prevalent in the body after iron. Zinc has many functions including in the immune system, protein synthesis, wound healing and enzyme activation. The highest levels of zinc are found in oysters but other foods are rich in zinc including seeds and nuts, legumes and grains, meat and poultry and dairy products.

A recent Cocrane review concluded that zinc supplements have little or no effect on common cold prevention but may reduce the duration of the illness. The review did suggest that zinc supplement use could be associated with an increase in adverse events including aberrations of taste, gastrointestinal discomfort, oral, nasal and pharyngeal dryness and headaches.

Vitamin C

Ascorbic acid or vitamin C is water soluble and is a powerful antioxidant to protect cells from damage as well as a critical role in the immune system and in wound healing. Vitamin C can be obtained in the diet from fruits and vegetables. Vitamin C is easily destroyed by heat so the highest amounts can be obtained from raw fruit and vegetables; steaming is less destructive than boiling.

Research suggests that Vitamin C does not prevent the common cold but does reduce the severity and duration of the illness.

Vitamin E is another antioxidant that is important in the immune response. Unlike vitamin C it is fat soluble so can be stored in the body. There are far fewer trials examining the effect of vitamin E on prevention of common cold and the results are mixed so conclusions are difficult to draw.

Vitamin D

It is well known that vitamin D is crucial in the metabolism of calcium in the body to keep bones healthy but it also plays a role in the immune system. The effect of vitamin D in the incidence and severity of the common cold remains inconclusive.