The difference between cold and flu

The common cold is often and easily confused with influenza. This blog is here for you to know what illness you're handling when symptoms arise, and the appropriate immediate actions to promote recovery.  

The flu can be distinguished from a common cold by the severity of symptoms and speed of symptom onset. While cold symptoms are generally mild and develop over several days, flu symptoms are much more severe and grow more rapidly.

Drawing of tissue box- Cold vs Flu

A quick overview of cold and influenza

Typical symptoms of the common cold

Primarily the symptoms are mild with a cold, such as:

  • Nasal swelling and congestion
  • Runny nose 
  • Sore throat
  • Cough 
  • Headache 
  • Low-grade fever 
  • Muscle aches
  • Malaise (general feeling of being unwell)

Influenza signs to look out for

The presence of digestive signs or severe body-wide symptoms, such as fatigue, fever, body aches, shortness of breath and malaise, may indicate an influenza infection:

  • Sudden onset of high fever
  • Fatigue 
  • Head and body aches
  • Cough, congestion 
  • Sore throat

Symptoms: The common cold vs influenza

The characteristic symptoms of the common cold can include nasal congestion and a runny nose. While in the flu, this can be common. A sore throat is a distinctive symptom of the common cold, while it is a potential symptom in influenza. 

A mild to moderate cough is characteristic of the common cold, however, cough symptoms are also typical of influenza, while ranging from severe. 

Headache is a common symptom in both illnesses, although it is usually mild in the common cold. 

Fever, feasible of being high is the tell-tale sign of influenza. Similarly, muscle aches are another characteristic symptom of the flu and can often be severe. However, fever and muscle aches are rare but typically mild in the common cold. 

Malaise (generally feeling unwell) and fatigue are common symptoms of the common cold, however, they are mostly mild. Though, in influenza, these can be severe and are characteristic symptoms.

Shortness of breath and diahorria with vomiting are typically uncommon in the flu. In the common cold, these are non-existent symptoms. 

Likewise, loss of smell (without nasal congestion) or taste is also non-existent for symptoms in both illnesses. Other neurological symptoms are not present in either disease.

Infection: Common cold vs influenza

The flu is a common respiratory infection caused by the influenza virus. Although the flu usually resolves on its own, it may progress to serious problems like pneumonia, especially in older people or people with suppressed immune systems.

The cause is influenza A, B or C, located in the upper and lower tracts. The onset is abrupt and the incubation period lasts from 1-4 days, while the entire duration of the illness ranges from 7 to 14 days. 

The common cold is the most frequent acute infectious illness. The common cold can be caused by more than 200 subtypes of rhinovirus, influenza viruses, and other common viruses. 

The infection occurs in the upper tract and has a gradual onset. The incubation period lasts 1-3 days and the typical duration is 7-10 days.  With the common cold, infection occurs when the virus reaches mucous membranes (eg, eyes, nose, mouth), often via direct contact or respiratory droplets from another infected person. 

When an influenza virus contacts a respiratory epithelial cell, such as those lining the nose or mouth, it binds to specific receptors on the cell surface. This may trigger a process by which the virus gains entry into the cell and releases its genetic material.

The cell is absorbed into generating proteins needed for viral replication. Infected cells in turn produce large amounts of virus that are shed into respiratory secretions, and they facilitate infection spread. 

In addition, they release signalling molecules that activate all types of immune cells and initiate the antiviral immune response. (1,2,3)

The time between initial infection and symptomatic illness called the incubation period, lasts typically one to four days, although viral shedding may begin as early as 12 hours after exposure to the influenza virus. (2) 

Studies indicate that viral replication and shedding likely peak around 48 hours after exposure, last for five to 10 days, and correspond with the severity of the illness. (2,4) 

A longer duration of viral shedding has been particularly observed in children, older adults, those with chronic disease, obese individuals, and those with compromised immune function. (2)

Treatment: Common cold vs influenza

A common cold generally resolves without treatment. Conventional treatments are mostly palliative and aim to shorten the duration of the illness and prevent complications such as a secondary bacterial infection.

Nonetheless, medication treatment is yet known to effectively decrease the duration, severity, or risk of complications. 

Antibiotics should not be taken for a common cold. Gargling (eg, with salt water) and nasal irrigation can help improve symptoms and reduce the duration of the illness. 

Some over-the-counter medications that may help relieve cold symptoms include Analgesics, Decongestants, Antihistamines, and others. The best nutrients to help aid the body's immune response and prevent the common cold are probiotics, vitamin D, and zinc lozenges. 

Contrary to what you may think, taking antibiotics for the flu is a big no-no. Doing so can contribute to the development of drug-resistant bacteria. Over-the-counter drugs (eg, mild analgesics, decongestants, etc.) can provide symptomatic relief for uncomplicated flu cases. 

Antiviral drugs are mainly used to treat patients at high risk of developing flu complications. Currently, only two oral antiviral drugs are being prescribed to treat the flu: Oseltamivir (Tamiflu) and Baloxavir marboxil (Xofluza)

Support: Nutrients for relief

Zinc has proven antiviral effects against several respiratory viruses, promoting their clearance from the surfaces of airways, preventing their entry into cells, and suppressing viral replication. Taking immediate action and using zinc in the form of a lozenge within 24 hours of symptom onset may reduce the duration and severity of a cold. (5,6)

Elderberry: Clinical research indicates elderberry extract, rich in anti-inflammatory and antioxidant polyphenols, may reduce influenza symptoms and shorten the duration of illness once ingestion starts within 48 hours of symptom onset. (7) 

Probiotics:  Multiple randomized controlled trials and several meta-analyses have shown probiotics reduce the risk of acute respiratory tract infections. 

Species of Lactobacillus and Bifidobacterium have been found to reduce the incidence and severity of upper respiratory viral infections, including the flu. (8)

Lactoferrin (as apolactoferrin) is an immune modulator capable of enhancing antimicrobial immune activity while reducing inflammation, has exhibited a broad spectrum of activity against bacteria, fungi, protozoa, and viruses. (9,10) 

Vitamin D: Numerous studies around the world have found correlations between low vitamin D status and increased risk of respiratory viral infections and poor outcomes. (11)

Curcumin: Numerous preclinical studies indicate curcumin may activate antiviral immunity, and it has demonstrated antiviral effects against various respiratory viruses. Curcumin also helps mitigate the inflammation associated with the immune response to infection. (12-16)

Melatonin: In addition to its role in promoting healthy sleep, melatonin is an antioxidant with anti-inflammatory activity. Some researchers have suggested taking 3–10 mg of melatonin at bedtime for respiratory immune health. (17,18) 

N-Acetylcysteine (NAC) inhibits cellular entry and replication of some respiratory viruses, assists in clearing thickened mucous from the airways, and suppresses inflammatory signalling. (19)

Vitamin C: When initiated soon after symptom onset, vitamin C may reduce the duration of influenza-like respiratory illness symptoms such as fever, chills, and body pain. (20-23) 

Selenium has been shown in preclinical studies to reduce the infectivity, replication, and virulence of several respiratory viruses. (24-26)

LicoriceActive constituents of liquorice have demonstrated antiviral effects against viral causes of respiratory infection as well as other viruses. (27-29)

Garlic compounds have demonstrated antiviral activity against respiratory viruses, such as rhinoviruses and influenza viruses, and have broad antimicrobial activity against bacterial and fungal causes of illness. (30) 

Quercetin may inhibit the replication and infectivity of a variety of common viruses that affect the respiratory tract as well as reduce inflammation induced by viral infection. (31-34)

Andrographis: Multiple randomized controlled trials and two meta-analyses have found andrographis extract, alone and in herbal combinations, reduced symptoms of upper respiratory tract infections. They may be especially helpful in alleviating cough and sore throat. (35-40) 

Green tea catechins have demonstrated antiviral actions against influenza and other respiratory viruses. Green tea may help prevent viral respiratory infections and may decrease flu-like symptoms by reducing inflammation. (41,42) 

Ginseng extracts have been shown to activate the antiviral immune response while reducing the inflammatory response, and clinical trials suggest it may lower the risk of the flu and improve the immune response to the flu vaccine. (43,44) 

Echinacea may reduce the incidence of colds and sick days, as well as reduce the risk of recurrent infections. (45,46) 

Beta-glucans: These prebiotic fibres may stimulate the body’s antimicrobial defence, prevent infection, and decrease upper respiratory tract infection symptoms. (47)

Read more


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