Next time you're at work, take a quick scan of your office. Notice anyone missing? When flu season is in full swing, there's a good chance that at least a few people are hacking up a lung at home. Hopefully, you can avoid becoming one of them, but it's important to know what early flu symptoms look like. The flu is known for coming on suddenly, but there are early signs if you know what to look for. That way, if you do catch the dreaded influenza, you'll be able to prepare yourself for what's to come. (Spoiler alert: There's a lot of coughing ahead.)
"A sudden feeling of overwhelming fatigue may appear before other symptoms," Niket Sonpal, an NYC-based internist and gastroenterologist, and adjunct assistant professor at Touro College of Osteopathic Medicine, tells Bustle over email. "People may attribute this to working hard, or a tough work out. While fatigue is also a symptom of the common cold, it is usually more severe with the flu. Scratchy or sore throat. In the earliest stages of the flu, your throat may feel irritated, scratchy, or sore. Generally there is just a feeling of 'malaise' that people may attribute to having a bad day and just needing a good night’s sleep."
In the Northern Hemisphere, flu season begins around October and peaks somewhere between December and February. It's no joke — most people recover within two weeks, but some people, including the elderly and very young, are at a greater risk for complications like pneumonia. Every year, according to the Centers for Disease Control (CDC), millions of people come down with the illness, hundreds of thousands are hospitalized, and thousands ultimately pass away.
The main way to prevent contracting the flu is to get your flu shot, if you are able. The vaccine not only helps protect you against seasonal influenza, but it also reduces the spread of the virus. "When more people get vaccinated against the flu, less flu can spread through that community," the CDC explains.
Unfortunately, it's possible (albeit unlikely) to catch the flu even if you get vaccinated, which is why you should know what symptoms to look out for. Read on to find out what early signs suggest you might have the flu.
According to Dr. Sonpal and guidelines from the Mayo Clinic, a high fever — or a fever over 100.4 degrees F — tends to be one of the first symptoms of the flu. This is where Dr. Sonpal notes that there is the most confusion with the flu and the cold, in that their first symptom may present similarly. That said, if it's the flu, it's generally accompanied by other defining symptoms that can indicate that you're dealing with the flu.
Per the CDC, fatigue is a sign that you could be coming down with the flu. The important thing here is to discern the difference between being tired and excessive exhaustion. Being tired is part of the winter blues; sudden, severe exhaustion may be a sign of the flu.
Dr. Sonpal lists "aching muscles" and "fatigue and weakness" as ways this particular symptom manifests; per Harvard Health, this symptom may also be the most persistent one, with feelings of fatigue lasting after other symptoms have faded.
Body aches can be one of the first signs to appear, per the CDC. The CDC distinguishes the type of body ache caused by colds and the type caused by the flu by noting that aches from colds are generally mild, whereas aches from the flu are more common and often more severe.
Headaches and chills are also symptoms to be on alert for if you think you have the flu. "Wrapping yourself in a warm blanket can increase your body temperature and reduce chills," Healthline suggests. "If you have body aches, you can take over-the-counter pain medication."
Dr. Sonpal lists "Dry, persistent cough" as yet another flu symptom; this means that when you cough, it's not accompanied by phlegm or mucus. For most people suffering flu, this is just an inconvenient symptom, but you should also monitor any significant changes in it — particularly because if the flu worsens, it can develop in to pneumonia, bronchitis, and asthma flare-ups, according to the Mayo Clinic.
The Mayo Clinic also lists "sore throat" and "nasal congestion" as two other possible symptoms of the flu; that said, the CDC notes that these two symptoms in particular are "common" with colds, and occur "sometimes" with the flu, so they might not necessarily be the best marker for determining whether or not you have the flu without a doctor's diagnosis.
Vomiting... Or Other Problems
Gastrointestinal problems like vomiting or diarrhea are more common in children, per the CDC, but it is possible for adults to start the flu that way. (Certain strains, like H1N1, are more likely to cause these symptoms than others.) If you find yourself stuck in the bathroom for hours at a time, be sure to stay as hydrated as you're able.
Suddenly Feeling "Off"
Unlike the common cold, the flu comes on suddenly; once someone is infected, symptoms show up between one and four days later. If you felt fine yesterday, but today you feel significantly worse without any other explanation, you may be dealing with the flu — in which case you should plan to stay home, to avoid infecting others, and make sure you're equipped to take care of yourself.
"Most people with the flu have mild illness and do not need medical care or antiviral drugs," Dr. Sonpal tells Bustle. "If you get sick with flu symptoms, in most cases, you should stay home and avoid contact with other people except to get medical care. Treat it and the aches that come with it with over-the-counter medications like acetaminophen, ibuprofen, or naproxen. Ask your doctor which is right for you."
This post was first published on January 23, 2018. It was updated on June 10, 2019.