Symptoms & treatment

Flu symptoms are usually more severe than cold symptoms and tend to come on suddenly. Flu-related illness can range from mild to severe, and in some cases may require hospitalization. Here are flu symptoms to look out for:

Most common

• Fever
• Cough
• Sore throat
• Runny or stuffy nose
• Muscle and body aches
• Headaches
• Fatigue

Less common

• Vomiting
• Diarrhea

To learn more about flu symptoms, visit our health encyclopedia.

RSV (respiratory syncytial virus) symptoms are usually mild and appear within 4 to 6 days after infection. In some cases, RSV can develop into a more severe illness like pneumonia. Very young children and older adults are more likely to develop life-threatening symptoms.

More common

• Congested or runny nose
• Decreased appetite
• Coughing
• Sneezing
• Fever
• Moderate wheezing

Less common — call your doctor²

• Extreme tiredness
• Refusal to drink liquids, breastfeed, or chestfeed
• Decreased number of wet diapers

Rare — call 911³

• Severe wheezing
• Rapid or labored breathing
• Bluish skin or fingernails

Symptoms of a COVID-19 infection can range from mild (like the common cold) to severe (like the flu). This can make it difficult to tell what virus is making you ill.

However, there are some common and uncommon COVID-19 symptoms to keep an eye out for:

Most common

• Fever
• Cough
• Shortness of breath

Less common

• Loss of taste and smell
• Diarrhea
• Sore throat
• Headache
• Repeated shaking with chills
• Muscle pain

Looking for more information on COVID-19? Visit kp.org/coronavirus.

Colds are less serious than the flu and typically come on gradually. They also generally don’t result in serious health problems or complications. Here are common and uncommon cold symptoms:

Most common

• Runny or stuffy nose
• Sore throat
• Sneezing

Less common

• Cough
• Fatigue

Rare

• Fevers over 100 degrees
• Headaches.  

Prescription medications called antiviral drugs can be used to treat the flu. But most people with the flu don’t need these. You should recover from the flu on your own within 7 to 10 days.

If you’re very sick or at high risk for flu complications, your doctor may recommend antiviral drugs. Flu antiviral drugs work best when started 1 to 2 days after your flu symptoms begin.

Your doctor won’t prescribe an antibiotic for the flu. Antibiotics don’t work for viruses. But sometimes people get bacterial infections, like ear infections, along with the flu. Your doctor may prescribe antibiotics in these cases.

You can take other steps to feel better while recovering at home. Learn more about home treatments and over-the-counter medicines for adults and children with the flu. 

Most people recover from the flu in 7 to 10 days without needing medical care. Stay home, avoid contact with others, and get plenty of rest and fluids. Learn more about home treatments and over-the-counter medicines for adults and children with the flu.

If a child or adult has severe flu or is at high risk for flu complications, a doctor may recommend antiviral drugs. Flu antiviral drugs work best when started 1 to 2 days after flu symptoms begin. 

Most people recover from the flu in 7 to 10 days without needing medical care. Stay home, avoid contact with others, and get plenty of rest and fluids. You can use self-care measures and over-the-counter medicines to treat fever, sore throat, congestion, and cough. 

Children with the flu usually get better in 7 to 10 days without needing medical care. Keep them home and away from others and encourage them to get plenty of rest and fluids. Learn more about home treatment for a child with the flu — and when you should call for help.