a sign for flu vaccines and Tamiflu on a city sidewalk
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When Is It Too Late To Take Tamiflu? Um, Call Your Doc Now

You’re shaking and rocking a 101 degree fever, and you feel like a minivan rolled right over your body. Chances are you might have the flu, momma. So in an attempt to get yourself back to wellness (and back to caring for your kiddos), you schedule an appointment with your doctor to cure what’s been ailing you. In the meantime, you wonder: When is it too late to take Tamiflu?

If you’re looking for something to relieve the chills and body ache, Oseltamivir is it. Commonly known by the brand name Tamiflu, it’s often prescribed by doctors to treat Influenza A and B. “Tamiflu is used to treat the symptoms of the flu virus,” Robert Williams M.D., a family medicine doctor, tells Romper. “These symptoms include stuffy nose, cough, sore throat, fever/chills, aches and malaise.” Tamiflu, which is prescribed by a health care professional, works by inhibiting enzymes that help the virus to spread to other cells in the body, the U.S. Food & Drug Administration reported. And once the meds begin to slow the spread of the virus, your white blood cells fight to bring you back to health.

So when is it too late to take Tamiflu? “In general, it's best to begin taking Tamiflu as early into the infection process as possible,” Taylor Graber M.D., an anesthesiologist, tells Romper. “Studies show it is most effective when started within the first 48 hours, and even more effective when started within 24-30 hours.” When taken early enough, it can shorten the duration of influenza symptoms by up to one day, the Cleveland Clinic reported. Not only can that reduce the severity of the illness, but it can also decrease your chances of having complications that could require hospitalization. Says Dr. Graber: “It is not a cure, but it prevents further spread of the virus once the infection has started.”

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Unfortunately, if you try to take Tamiflu after that 48-hour window, the medication might not work. “For normal, healthy adults and children with normal immune systems, the medication will be of little benefit if started after 48 hours,” says Dr. Graber. “Taking the medication at this point does not decrease the duration of the illness, but does begin to increase the risk of anti-viral resistance.” And that’s a problem, because if pop a Tamiflu 48 hours into your illness, you might actually be doing more potential damage. “There’s the risk of the virus becoming resistant to the medication and becoming less effective over time,” advises Dr. Graber. “This is why you should only take Tamiflu when needed, and only when it would be helpful.” And since Tamiflu is for the flu (and the flu only), you shouldn't take it even if you have a horrible head cold.

What happens, then, if you realize that you have the flu and more than two days have passed? Although it might be too late to take Tamiflu, you can always try to soothe some of the symptoms by taking Tylenol or ibuprofen to treat the pain and fever. “Staying hydrated is also key, since dehydration can worsen the symptoms of the illness,” advises Dr. Graber.

Although Tamiflu can’t stop the flu entirely, it can help shorten the duration and severity of your aches and pains. Like everything else, though, early diagnosis is key, so seek medical help if you’re starting to feel sick, and you’ll be back to the grind in no time.

Experts used:

Dr. Taylor Graber MD, , an anesthesiologist in San Diego, CA

Dr. Robert Williams, MD, a family medicine doctor in Lakewood, CO