Colds & flu: Symptoms, treatment, and prevention

What is the difference between a cold and the flu?

While colds and the flu share some characteristics, there are also key differences.

Colds. The common cold (also called viral rhinitis) is an upper respiratory infection that may be caused by one of more than 200 viruses. The most common are rhinoviruses, which generate up to 40% of colds, most often in the early fall and spring. Other viruses that can trigger colds include adenoviruses, respiratory syncytial virus, and seasonal coronaviruses (which should not be confused with SARS-CoV-2, the coronavirus that causes COVID-19). Colds are most often transmitted by contact with germs from the nose and/or mouth via coughing, sneezing, or hand-to-hand contact. Although there is no cure for the common cold, some therapies can help treat and manage symptoms.

Flu. Influenza (known as the flu) is typically caused by either the influenza A or B virus. Most flu outbreaks occur during the winter. The influenza virus is quite contagious and is typically spread through the air or by direct contact with an infected person. Getting an annual flu vaccine at the beginning of flu season in October or November can reduce the chances of getting the flu and transmitting it to others.

Common cold: Symptoms and treatment

Symptoms of the common cold usually affect the nose, throat, head, and chest. They typically peak on the second to fourth days of infection and last about one week. Common cold symptoms include sore throat, stuffy or runny nose, sneezing, and nagging cough. Fatigue and general aches and pain may also occur. People are most infectious during the first 24 hours of the illness and usually remain contagious for as long as they have symptoms.

Up to 25% of people may have lingering or persistent cold symptoms that last for several weeks, but symptoms should get better by 10 days. Call your health care provider if

• symptoms are generally getting worse
• you develop a fever after this time
• your cough is worsening or not improving
• you cough up blood
• you have trouble breathing.

Although there is no cure for the common cold, some therapies can help treat and manage symptoms. These include:

• getting enough rest
• drinking plenty of fluids
• gargling with warm salt water to ease a sore throat
• inhaling steam from a hot shower, vaporizer, or humidifier to help clear nasal congestion.

Over-the-counter medications also can help manage cold symptoms.

Aches and pain. Acetaminophen (Tylenol) can relieve mild to moderate pain. Nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen (Advil, Motrin) and naproxen sodium (Aleve) also help with pain and inflammation.

Congestion. Ingredients like pseudoephedrine (Sudafed, Advil Cold & Sinus, others), phenylephrine (Sudafed PE, Neo-Synephrine, others), and oxymetazoline nasal spray (Afrin) narrow swollen blood vessels in the nose to relieve congestion.

Cough and thick mucus. A cough isn’t always bad, as it helps to loosen and remove excess mucus and phlegm causing chest congestion. But if a cough becomes bothersome or interferes with sleep, try a cough suppressant such as dextromethorphan (Triaminic Cold & Cough, others), an expectorant like guaifenesin (Mucinex, others), or combination medicines (Robitussin Maximum Strength, others). Cough suppressants stifle the urge to cough, while expectorants thin mucus in your airway to make it easier to remove.

Over-the-counter cold medicines that address more than one symptom are an option if you have multiple and/or severe symptoms. Make sure to take only the recommended dosage on the package.

Flu: Symptoms and treatment

Flu season typically begins in October or November and peaks between December and February. However, significant flu activity can last as late as May.

Influenza symptoms and illness severity can vary depending on the virus type, a person’s age, and their overall health. Although it is a respiratory virus, the flu can affect other body systems and make you feel sick all over.

Common symptoms include:

• moderate to high fever (101º to 103º F)
• chills
• muscle and joint aches
• headaches
• fatigue
• cough
• sore throat
• runny nose
• diarrhea
• dizziness.

Influenza symptoms generally last five to seven days after they begin, but can range from 24 hours to a week or longer. As long as you have flu symptoms, you are contagious.

To ease symptoms, you can follow the same treatment protocol as the common cold: plenty of rest and fluids and taking over-the-counter medications to alleviate fever and pain, such as acetaminophen (Tylenol) and nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen (Advil, Motrin) and naproxen (Aleve).

Flu treatment can also include antiviral medications to lessen symptoms and shorten illness duration. Prescription drugs such as oseltamivir (Tamiflu), zanamivir (Relenza), baloxavir marboxil (XOFLUZA), and peramivir (Rapivab) must be started within the first 48 hours of symptoms appearing to be most effective.

Some people develop severe complications from the flu. Pneumonia is the most serious, but other complications include asthma attacks, ear infections, bronchitis, sinusitis, inflammation of the heart or other muscles, and inflammation of the nervous system. Notify your doctor if you experience

• chest pain
• shortness of breath
• ear pain
• fever that does not go away after four days
• a cough that produces blood or thick, foul-smelling mucus.

Many flu symptoms overlap with COVID-19 symptoms. People can get tested at home, their doctor's office, or pharmacy with a combined COVID-19 and flu test.

Should I get a flu shot?

The single best way to prevent influenza is to get a flu vaccine (commonly known as a flu shot) each year. Keep in mind that flu vaccines do not protect you from non-influenza viruses such as colds, COVID-19, or other flulike illnesses.

Children 6 months or older, teenagers, and adults should all be vaccinated from the flu. Vaccination is especially important for people at high risk for serious flu-related complications, and those who live with or care for people at high risk, including:

• children under age 5, especially those under age 2
• children of any age on aspirin therapy
• medical personnel
• pregnant women and women planning to become pregnant during the flu season
• people age 65 and older
• people of any age with anemia, heart disease, diabetes, kidney disease, a compromised immune system, asthma, or other lung diseases
• people who live in a nursing home or other long-term-care facility.

Some people should consult a physician before being vaccinated. They include people who have had allergic reactions to the vaccine, have allergies to any of the vaccine ingredients like eggs, and those who have had Guillain-Barre syndrome, a disease in which the immune system attacks the nerves.

The best time to get vaccinated is at the beginning of flu season in September or October. However, getting it in December or even later can still be beneficial since peak influenza activity can occur as late as February. You can get the vaccine at your doctor’s office and at some workplaces, supermarkets, and drugstores. (For local pharmacies offering vaccines, search Find pharmacies near you.)

You must get a flu vaccine every year to be protected. The vaccine is modified annually based on the strains of the flu viruses that scientists anticipate will circulate that winter. Sometimes an unpredicted strain appears after the vaccine has been made. This is one reason you may still get the flu, even if you’ve been vaccinated. But if this happens, the disease is usually milder because the vaccine provides some protection.

The vaccine is made from an inactivated virus that can’t cause infection. In other words, the flu shot can’t give you the flu. About two weeks after you get vaccinated, your immune system develops proteins called antibodies that protect against infection from flu viruses.

The flu vaccine can also be delivered via a nasal spray. The nasal vaccine contains weakened — not inactivated — virus, and may not be suitable for everyone. Talk to your health care provider to determine whether it is right for you.

In addition to the standard-dose flu shot, other available types of flu vaccines include:

• the high-dose influenza vaccine, which is designed for people ages 65 and older. It contains four times the dose of antigens found in the standard flu shot.
• the adjuvant flu vaccine, which has an added ingredient that produces a stronger immune response in people ages 65 and older.

Common side effects of a flu vaccine are soreness, redness, and swelling at the injection site. Other possible side effects include low-grade fever, fatigue, and aching muscles. These may begin six to 12 hours after vaccination and can last up to two days.