Considering the severity of this year’s flu season, it’s tempting to think every cough, muscle ache, and hint of a fever is a sign you caught the flu.
The confusion is totally understandable: There are a ton of other illnesses with copy-cat flu-like symptoms.
The only way to know for sure you have the flu is to get tested–but there are subtle clues to help you distinguish between influenza and something else. Here are a few of the many conditions that can cause flu-like symptoms.
Both colds and influenza are viral illnesses, they both tend to occur in the same seasons, and they have many overlapping symptoms, like a sore throat and a stuffy nose.
The flu and strep throat share many symptoms, but there are two you may find in the flu but never in strep: cough and nasal congestion.
Strep throat may also bring swollen lymph nodes, swollen tonsils, a skin rash, or white blotches on the tonsils. None of these is typical of the flu.
Pneumonia can come separately from the flu or it can be a secondary complication of getting sick. You may even look like you’re over the flu and then bang–you’re stricken with another infection. “People are getting the flu and maybe even riding it out, and a week or so later, they’re coming in with pneumonia,” Weston says.
Pneumonia that’s not related to the flu is often viral; viral pneumonia is also typically milder than the bacterial kind. You may also have some congestion, coughing, and fatigue, all of which could point to the flu–but in this case, they’re simply flu-like symptoms.
Doctors can listen for telltale signs of pneumonia by putting a stethoscope to your chest, says Dr. Peterson.
Mono is also called the “kissing disease” because it can be passed through saliva (along with coughing, sneezing, and sharing utensils).
Mono also drags on longer than the flu, often lasting two to four weeks–but sometimes six months or longer.
Meningitis is inflammation of the membranes (meninges) that cover the brain and spinal cord.
Viral meningitis is like colds and the flu in that most people recover on their own in a week or so. Bacterial meningitis, however, can cause brain damage and even death if it’s not treated promptly with antibiotics.
Acute bronchitis not only has cold- and flu-like symptoms, it’s even caused by many of the same viruses.
There’s no test for bronchitis like there is for the flu, so doctors usually diagnose it by asking about symptoms and examining you. Bronchitis treatment consists of rest, drinking lots of fluids, and taking meds that can relieve symptoms.
Respiratory syncytial virus
Respiratory syncytial virus or RSV has symptoms that can also be mistaken for the flu (or a cold). “It can cause runny nose and cough,” says Afif El-Hasan, MD, a spokesperson for the American Lung Association and a pediatrician with Kaiser Permanente.
When to contact your doctor
This year’s flu is so bad that more people are going to the doctor for flu-like symptoms than usual–and rightly so. “If you suspect you have the flu, then you should see the doctor within 48 hours because [antiviral] medicine has to be taken very quickly,” Dr. Peterson says. “Err on the side of caution.”
Most viral infections, including the flu, tend to go away on their own. But be on the alert for signs of trouble such as shortness of breath, chest or abdominal pain, dizziness, or dehydration. If you’re experiencing any of these in addition to your flu-like symptoms, call your doctor or head to an emergency room.