What causes a cold or the flu?

The common cold and the flu (influenza) are caused by viruses that infect the upper respiratory system – the nose, mouth, throat, and lungs.

How can I tell if I have a cold or the flu?

Colds and flu have many of the same symptoms. However, cold symptoms are usually milder than flu symptoms and develop more slowly.

Symptoms of Colds and Flu
Symptom Cold Flu
Fever Adults-rare; children- sometimes High fever (100°F and higher; can last 3 to 4 days)
Runny nose Common (Nasal discharge may have a yellow- or green-colored tint) Sometimes
Stuffy nose Common Sometimes
Headache Sometimes (usually mild) Common
Body aches Sometimes (usually mild) Common (can be severe)
Fatigue Sometimes(usually mild) Common (can last up to 2-3 weeks)
Exhaustion Never Common (at the start of the flu)
Chills, sweat No Common (extreme)
Nausea Uncommon Common
Loss of appetite Sometimes Common
Sneezing Common Sometimes
Cough Common Common (can be intense)
Sore throat Common Sometimes
Chest congestion, discomfort Common (mild to moderate) Common (can be severe)
Watery eyes Common Sometimes
What medicines are used to cure colds and flu?

No medicines can "cure" colds and flu. There are many over-the-counter medicines that can ease the discomfort caused by the symptoms of colds and flu. In addition, there are prescription medicines and a vaccine that can treat and prevent the flu.

Note on antibiotics: Antibiotics don't cure viral infections, such as colds and flu, and should not be taken to treat them. Antibiotics are used to treat bacterial infections, such as strep throat and ear, skin, and urinary tract infections. Using antibiotics for infections they are not able to treat makes the antibiotics less effective for infections they are supposed to treat (a situation called antibiotic resistance).

Discomfort from specific symptoms of colds and flu can be eased with the following types of OTC medicines:

  • To reduce fever and pain -- analgesics. Acetaminophen (Tylenol®) is generally preferred. Ibuprofen (Advil®) or naproxen (Naprosyn®) is also commonly used. Aspirin should be avoided due to its risk of developing Reye's syndrome. (Reye's syndrome is a condition that affects all body organs and is most harmful to the brain and liver.) Note on acetaminophen: Read all cold medicine package labels. Do not take more than one drug that contains acetaminophen. Taking too much acetaminophen can damage your liver. Acetaminophen doses should not exceed 4 grams per day. Individuals with liver damage or liver problems should not exceed 2 grams of acetaminophen per day.
    To dry out the nose -- antihistamines. Try an antihistamine, such as diphenhydramine (Benadryl®). Because these products can make you sleepy, avoid driving and other complex tasks while taking these medicines. Loratadine (Claritin®), available over-the-counter (OTC), is a non-drowsy alternative, but may not be as effective as other antihistamines for reducing cold and flu symptoms. Other OTC antihistamines include Allegra®, Zyrtec®, and Xyzal®.
  • To relieve a stuffy, clogged nose -- decongestants. Try an oral decongestant, such as pseudoephedrine (Sudafed®). However, insomnia, nervousness, and irritability can occur when taking these drugs. Those who are pregnant or have uncontrolled high blood pressure should avoid pseudoephedrine products. Often decongestants are combined with other drugs (especially antihistamines) in OTC medicines. A "-D" at the end of a medicine's name means it includes an oral decongestant.
  • To relieve a runny nose or sinus pressure -- nasal steroids. Medications like fluticasone (Flonase®, available without a prescription) or mometasone (Nasonex®; prescription needed) can relieve symptoms. These medicines are also used for seasonal allergies. These are not the same as Afrin® or other OTC nasal preparations. Antihistamines will also help.
  • To make blowing your nose easier or loosening cough/mucus production -- expectorants. Try guaifenesin (Robitussin®, Mucofen®, Humibid LA®, Mucinex®, Humibid E®). These products help thin the thick, discolored drainage coming out of the nose and mouth.
  • To reduce coughing -- antitussives. Dextromethorphan can help suppress cough.
  • To relieve a sore throat: Try throat lozenges (such as Cepacol®) or gargle with warm salt water a few times a day. Analgesics are also helpful.
  • For other symptoms: OTC cold products (for example, Nyquil® or Tylenol Cold & Sinus®) can provide much relief. Be sure to read product labels to find the best cold preparation to match your symptoms and to determine if that medicine is safe for you.

What are other ways to treat and prevent the flu?

Antiviral prescription medicines and an annual flu vaccine are available for treating and preventing the flu.

Prescription anti-flu medicines include amantadine (Symmetrel®), rimantadine (Flumadine®), zanamivir (Relenza®), and oseltamivir (Tamiflu®). These drugs do not cure the flu, but they can make the symptoms milder and make you feel better more quickly. They are only effective when used in the first 48 hours of flu-like symptoms.

These drugs are not needed for healthy people who get the flu. They are usually reserved for people who are very sick with the flu (for example, those who have been hospitalized) or those who are at risk of complications from the flu, such as people with long-term chronic medical conditions (such as diabetes or chronic obstructive lung disease, asthma) or older age.

Flu vaccine (by shot and nasal spray). Although there is currently no vaccine against the common cold, there is a vaccine to prevent the flu. The vaccine is available by both shot and nasal spray. It works by exposing the immune system to the viruses. The body responds by building antibodies (the body's defense system) against the flu. The flu shot contains dead flu viruses. The nasal spray contains live, but weakened, flu viruses. The nasal spray is only approved for healthy children and adults 2 to 49 years old and who are not pregnant.

Who should get an annual flu shot?

The Centers for Disease Control (CDC) recommends the following groups receive an annual flu vaccine shot between November and February (flu season):

  • All people aged 6 months and older

It is especially important for certain individuals at high risk of flu complications and those who come in contact with people at high risk of complications to receive the flu vaccine. These people at high risk include:

  • Residents of nursing homes and other long-term care facilities
  • People who have chronic medical conditions such as asthma, heart disease, diabetes, kidney and liver disorders, and chronic lung diseases
  • People with a weakened immune system, for example, people with cancer, HIV/AIDS, or chronic steroid users
  • Household members and caregivers of patients at risk of complications from the flu
  • Women who are -- or will be -- pregnant during the flu season (regardless of trimester)
  • Healthcare workers who come into close contact with patients in hospitals, nursing homes, long-term care facilities, and other healthcare facilities
  • Infants and children ages 6 months through 18 years who are taking long-term aspirin therapy. This puts these individuals at risk for experiencing Reye syndrome after flu infection.
  • American Indians/Alaska natives
  • People who have close contact with children under 5 years of age -- for example, people who live with children, nannies, and providers of daycare services
  • People who are morbidly obese (body-mass index of 40 or higher)

Can I get the flu from the flu shot or nasal spray?

No, you cannot get the flu from the flu shot or nasal spray. However, some people can still get the flu even though they had the vaccine. In these cases, the flu symptoms are milder compared with unvaccinated people who get the flu.

What are the complications of colds and the flu?

Examples of complications from colds and the flu include:

Complications triggered by the flu can lead to hospitalization, life-threatening situations, and even death.

When should I call my doctor?

Call if you experience any of the following:

  • symptoms that last or get worse after 10 days
  • shortness of breath or trouble breathing
  • high fever (greater than 102°F) for 3 or more days
  • pain or pressure in your chest
  • coughing up blood
  • sudden dizziness or feeling faint
  • severe vomiting
  • confusion
  • severe sinus pain
  • swollen glands in neck or jaw

What can I do to prevent getting colds and the flu?

Wash your hands frequently with soap and water or alcoholic hand wipes. Cold and flu viruses are spread by touching your nose or mouth after touching an infected person, breathing in the air of an infected person's sneeze or cough, or touching objects that have come in contact with the virus and then touching your nose.

Other prevention tips are to eat healthy, exercise, get plenty of sleep, drink plenty of liquids (try to drink eight 8-ounce glasses of fluid/day), and avoid close contact with people who have colds. Also, get an annual flu vaccine.


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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. This document was last reviewed on: 8/1/2016...#13756