Both cold and flu are respiratory infections caused by viruses. Both are contagious, and both occur during the cold season. They share similar symptoms, and it can be difficult at times to tell the difference between them. While a doctor is best to provide the correct diagnosis, you can also get an idea if you have a cold rather than flu, if you look at the differences between them. So what are the differences between cold and flu?
The signs and symptoms
Symptoms start gradually in case of a common cold, while the onset is abrupt in case of the flu. Fever and chills are rarely associated with the common cold but are usually seen in cases of flu. Muscle aches, headaches, weakness, and fatigue are rarely experienced and typically mild in case of a common cold, but fairly common signs and symptoms associated with flu. Stuffy nose and sore throat are highly suggestive of a cold and are rarely seen in cases of flu. Chest discomfort and cough can occur in both common cold and flu, but these symptoms are more likely seen in individuals who get the flu. Overall, the common cold is a milder version of the flu, while the flu is more likely to cause complications. The main clue that you may have the flu and not a cold is that the symptoms come seemingly out of the blue and are quite severe. The main clue that you have a common cold rather than the flu is a scratchy throat that lasts a day or two, followed by sneezing, runny nose, and cough by the fourth and fifth day. A common cold usually lasts up to a week, while the flu can persist longer.
Make sure you have a thermometer at home, as another clue to differentiate these two conditions is your body’s temperature. The common cold rarely causes a fever over 101 degrees, while it is a common finding with flu.
The complications
The flu is more likely to cause severe symptoms and complications, particularly bronchitis (chest old), pneumonia with a secondary bacterial infection, as well as sinus infections and ear infections. Flu can worsen pre-existing conditions like heart failure, asthma, and diabetes, causing muscle inflammation and inflammation around the heart (pericarditis). Complications of the common cold typically include sinus infections and middle ear infections. Bronchitis and pneumonia can also develop after a common cold but are more likely to follow the flu. Again, it is important to notice if the symptoms change, because secondary bacterial infections need treatment with antibiotics.
- Productive cough with greenish or yellow mucus, fever, chills, extreme fatigue, loss of appetite, severe chest pain, fast breathing and heartbeats suggest pneumonia after a flu.
- Sinusitis develops when viruses cause inflammation of the sinuses, creating the perfect environment for bacteria to grow. Signs and symptoms suggesting sinusitis include headache, fever, stuffy nose, yellow or greenish music, toothaches, pain in the sinus areas, cough and bad breath.
- Bronchitis or chest cold is another possible complication, causing a persistent productive cough (lasting 2-3 weeks) with a yellow greenish or clear mucus.
- Ear infections cause pressure or fullness in the ears, ear pain, muffled hearing and sometimes fluid is seen drawing from the ears. One or both ears can be affected.
- A high fever (over 102 F), associated with sudden severe face pain, vision problems, confusion, stiff neck and difficulty breathing are possible signs of meningitis secondary to a cold or a flu, and require immediate medical attention.
The treatment
In both cases, it is important to get adequate rest, stay well hydrated, and drink hot teas. Saline solutions (neti Pot) and menthol ointments can be applied to the chest. The common cold is usually responsible for milder symptoms and can improve on its own. Decongestants and expectorants can be used to manage a stuffy and runny nose. In case of the flu, pain and fever relievers such as acetaminophen and ibuprofen can help relieve the symptoms. Be careful with the over-the-counter drugs, as many formulas contain multiple ingredients and it is easy to overdose when you use single drugs and combinations at the same time. Always read the label.
For flu, there are both over-the-counter and prescription antiviral drugs. The prescription drugs are recommended for flu only, in case of severe symptoms or for those at risk to develop complications. Bacterial infections which follow the flu or a cold are treated with antibiotics.
Preventive therapies in the form of vaccines are available for flu, but not for the common cold. Vaccines are available also for pneumococcus to prevent pneumonia, and meningococcus to prevent meningitis.
Flu is caused by influenza viruses, while common cold can be caused by over 200 hundred different viruses, especially rhinoviruses and common coronaviruses (not to be confused with the new SARS-COV-2 coronavirus which is responsible for COVID-19). Talk to the doctor when in doubt, as COVID-19 causes flu-like symptoms, and additional investigations like testing will be recommended.
