Colds, flus and other respiratory illnesses are often more common in colder months. People are indoors more often, allowing viruses to pass more easily from one person to another. And the cold, dry air may weaken resistance.

If you’re coughing and sneezing this winter, how do you know if you have a cold or something more serious? Do you need antibiotics? Are you contagious?

Michael Albert, M.D., a concierge physician with Johns Hopkins Personalized Care, suggests this quick guide to help diagnose and treat what’s ailing you.

Common Cold

What is it? Your nose and throat are infected. Your ears may also be infected.

How did I get it? Somebody coughed or sneezed near you, or you touched a contaminated surface, like a doorknob. More than 200 viruses can cause colds. The most common is the rhinovirus.

How I feel: Yucky. You probably have a runny nose, scratchy throat, low-grade fever, fatigue, chills and aches. And you probably are sneezing and coughing.

What should I do? You probably know that there’s no cure for the common cold. Decongestants, cough drops and antihistamines can help with symptoms. Rest and liquids may speed your recovery.

How long will it last? A few days to several weeks.

When can I go back to work? Most people are contagious for about a week, starting the day before they have symptoms. If you feel well enough to continue working, or if you go back within a day or two, wash your hands frequently and avoid close contact with others until you’re done coughing and sneezing.

How common is it? Very. Of all illnesses, common colds are blamed for the most days off work or school and the most visits to health care practitioners.

See a doctor if: Symptoms linger beyond a few days or get worse, or if new symptoms develop.

Learn more about common colds.

Flu

What is it? Your upper respiratory tract (nose, throat, and upper airways) is infected.

How did I get it? You got the influenza (flu) virus from airborne droplets sneezed or coughed, or by touching contaminated surfaces. Flu viruses keep evolving, which is why influenza vaccines are updated every year.

How I feel: Generally, terrible! You’re exhausted, and you may have a fever, headache and body aches. You’re likely sneezing and coughing, and your throat may be sore.

What should I do? Relieve symptoms with rest, fluids and medicines. In severe cases, or for individuals at high risk for complications, antiviral medications like oseltamivir (Tamiflu) may be prescribed. Antivirals are most effective when started within 48 hours to reduce the flu’s duration, severity and risk of complications.

How long will it last? The worst of it — fever and aches — is often over in three to five days. The coughing and general fatigue can linger two weeks or more.

When can I go back to work? Wait at least five days after onset of symptoms and 24 hours after your fever breaks.

How common is it? Every year, between 5% and 20% of Americans get the flu, sending many to the hospital with severe complications.

See a doctor if: Symptoms get worse, particularly a worsening cough after the first week, or if you have a condition or situation that makes you vulnerable to flu complications.

Learn more about the flu.

COVID-19

What is it? Your upper respiratory tract (nose, throat and upper airways) is infected.

How did I get it? You got COVID-19 from close person-to-person contact, or through airborne droplets released by an infected person speaking, coughing or sneezing.

Staying up to date on vaccinations, washing your hands, covering your mouth when you sneeze or cough and wearing a mask if you are sick help avoid getting — or spreading — COVID, which can be dangerous, particularly to those with a weakened immune system.

How I feel: It depends. While some people with COVID have few or no symptoms, others have a sore throat, congestion and cough, or runny nose and fever or chills. You may lose your sense of smell or taste, and experience shortness of breath or body aches. Upset stomach, diarrhea or vomiting are also possible.

What should I do? Isolate, and notify your doctor. You can treat most cases at home. Get plenty of rest, drink fluids and take over-the-counter fever reducers to address symptoms. In severe COVID infection, or in people at risk, your doctor may prescribe Paxlovid to reduce the virus’ duration, severity and risk of complications.

How long will it last? Acute COVID can hang on for a week or two for mild or moderate cases, longer for severe infections. Post-COVID symptoms, such as lingering cough, on-and-off fever, fatigue, memory issues and changes to your senses of smell or taste, can persist for weeks or even months.

When can I go back to work? Once you have been feeling better and fever-free for 24 hours, you may return to work. Wearing a mask while you have symptoms can help protect others around you. If you are a health care worker, check with your employer for specific guidance.

How common is it? COVID is contagious and common. COVID outbreaks tend to occur in waves, often associated with new variants of the coronavirus and sometimes the fall and winter months when people gather indoors.

See a doctor if: You have difficulty breathing, persistent pain or pressure in the chest, new confusion, inability to wake up or stay awake, or bluish lips or face.

Learn more about COVID-19.

RSV (Respiratory Syncytial Virus)

What is it? RSV is a viral infection that can lead to inflammation of the respiratory tract and lungs. In children younger than 1 year, RSV is the most common respiratory cause for hospital admissions.

Who is most at risk of severe RSV infection? Infants (especially those born premature), children, older adults, people with heart and/or lung problems, and people with weakened immune systems.

How long does it last? Most children and adults with RSV will recover in one to two weeks.

How common is it? Very. Among infants, 97% get RSV by age 2, and 60,000 to 160,000 older adults in the U.S. are hospitalized with RSV every year.

How might my child get it? Your child could become infected by contacting fluids from an infected friend’s nose or mouth. Outbreaks often occur in classrooms, community centers and child care centers.

How will my child feel? Your child will feel like they have a cold. They may experience a runny nose, coughing, sneezing, wheezing, a decreased appetite and low fever.

How should I care for my child? Provide general supportive care: Ensure your child gets enough rest and drinks plenty of fluids. Monitor their breathing. If needed, provide them with over-the-counter children’s acetaminophen to ease symptoms. RSV vaccines approved by the Food and Drug Administration are available for children under age 2, adults age 60 and over, and people in the third trimester of pregnancy.

When can my child go back to day care or school? Your child can return to day care or school about three to eight days after their first exposure to the virus. However, if an infant or someone with a weak immune system contracts the disease, they may be contagious for up to four weeks.

See a doctor if: Your child experiences a high fever, a bad cough, wheezing, labored breathing and/or decreased appetite.

Learn more about RSV.

Acute Bronchitis

What is it? Inflamed bronchi (the big tubes that bring air to the lungs) result in too much mucus.

How did I get it? Probably from a cold or flu virus — so getting a flu shot lowers your risk — or you might have inhaled bacteria. You’re particularly susceptible if you smoke or have allergies, sinusitis, or enlarged tonsils or adenoids.

How I feel: Like you can’t stop coughing. You probably started with a dry cough that soon became mucus-producing. You may also have aches and pains, chills, headache, runny nose, sore throat, shortness of breath, watery eyes and wheezing.

What should I do? Not much. It will clear up on its own — unless it progresses to pneumonia, which can be treated with antibiotics. Meanwhile, a humidifier, cough medicine and pain relievers can ease your symptoms.

How long will it last? About two weeks for most symptoms, though the cough can linger for a couple of months.

When can I go back to work? Bronchitis is not contagious once the initial viral phase subsides after a few days, so return to work when you feel strong enough.

How common is it? About 5% of adults and 6% of children are diagnosed with acute bronchitis in the U.S. each year.

See a doctor if: Symptoms don’t improve, or if they get worse.

Learn more about acute bronchitis.

Chronic Bronchitis

What is it? Inflamed bronchi (the big tubes that bring air to the lungs) result in overproduction of mucus. Bronchitis is considered chronic if you have a mucus-producing cough at least three months per year, two years in a row.

How did I get it? Probably from smoking, but irritants like air pollution may also be to blame.

How I feel: You have a persistent cough, plus chest discomfort and difficulty breathing.

What should I do? The goal of treatment is to reduce symptoms so you can breathe more easily. If you smoke, quitting is recommended. Oral or inhaled medications can open your airways. In severe cases, you might consider lung reduction surgery or a lung transplant.

How long will it last? Chronic bronchitis may ebb and flow, but it’s not going away.

When can I go back to work? Chronic bronchitis is not contagious, so work if you are able.

How common is it? Each year, about 9 million Americans are diagnosed with chronic bronchitis.

See a doctor if: You have a cough that lasts more than three weeks, produces bloody or discolored mucus, or is paired with a fever. Err on the side of caution and see a doctor even if you only suspect you have bronchitis — early treatment decreases the risk of lung damage.

Learn more about chronic bronchitis.

Pneumonia

What is it? Your lungs are infected, causing air sacs to fill with pus and other liquids.

How did I get it? Viruses are responsible for about one-third of cases. The rest are caused by bacteria or fungi that are inhaled, particularly by people weakened by surgery, illness, age or smoking.

How I feel: Symptom severity ranges from mild to life-threatening and can include confusion, fever, a cough that produces mucus, heavy sweating, shaking chills, lack of appetite, rapid breathing and pulse, shortness of breath that gets worse with activity, and stabbing pain in the chest that’s worse with coughing or deep breathing.

What should I do? If you have viral pneumonia, rest, eat well and drink plenty of fluids. Bacterial pneumonia can be treated with antibiotics. In both cases, medications can ease your fever and cough.

How long will it last? Most people respond well to treatment and recover in one to three weeks, but pneumonia can be very serious and even deadly.

When can I go back to work? If you have bacterial pneumonia, the risk of infecting others drops sharply two days after taking antibiotics. Viral pneumonia is less contagious, but avoid others if you have a fever. You’ll get better sooner if you don’t rush back to work before you’re ready.

How common is it? About 3 million people in the U.S. are diagnosed with pneumonia each year, and about 50,000 die because of it.

See a doctor if: Your cough gets worse or doesn’t improve, you cough up pus, you have a persistent fever higher than 102 degrees, you have shaking chills, or breathing makes your chest hurt. Don’t delay seeing a doctor if you have underlying health conditions, such as heart or lung problems.

Learn more about pneumonia.

Whooping Cough

What is it? Also known as pertussis, whooping cough is a serious and very contagious bacterial infection that mainly affects infants and young children.

How did I get it? A bacterium called Bordetella pertussis, which is spread by coughing, sneezing and even breathing, causes whooping cough.

How I feel: It starts like a common cold, and progresses to include coughing spells that end with a whooping sound as you gulp for air. Other symptoms include fever, sneezing, runny nose and watery eyes.

What should I do? Your best bet is early treatment with antibiotics, which may reduce the infection and will make you less contagious. Stay warm, drink lots of fluids and limit exposure to things that make you cough, like smoke or dust.

How long will it last? Up to 10 weeks. It can lead to pneumonia and other complications.

When can I go back to work? Avoid contact with others until you have been treated with antibiotics for five days.

How common is it? Whooping cough is on the rise, because fewer children are getting vaccinations and then boosters every 10 years. In recent years, between 10,000 and 40,000 cases have been reported annually nationwide.

See a doctor if: You suspect you have whooping cough. Also, ask your primary care physician if you are up to date on your Tdap booster, which can help prevent the infection.

Learn more about whooping cough.