Drug Fever
All the glitters is not gold
All who wander are not lost
All who are febrile are not infected.
–ancient Elvis saying.
Fever, fever fever. 780.6.
Why does the patient have a fever?
This week, one of the patients had a fever due to drugs. She came in infected, the infection resolved, the white count decreased, she felt better and, after a period of time, the fever returned. Routine work up was negative so they called me.
I didn’t find any infection to account for either, so I looked at the drug list. Could it be drug fever?
Vancomycin and Zosin were the only drugs to worry about.
When do you worry about drug fever? The patient has a fever and they are on a drug. hence the name. There are other hints. Continuous fever, where it temperature does not fall to normal, is an inconsistent finding. Eosinophilia is another. It can be any drug, any time, first dose or the hundredth.
You have to play the odds: antibiotics are common causes, and vancomycin, which, due to MRSA, I have had to use by the bucketful, seems very common, as are beta lactams and sulfa. Of the unimportant (ie non antibiotics drugs) H2 blockers and anti seizure drugs lead the list.
In the end you have to stop the drug and see if the fever goes away, usually in about four half-lives of the drug. The only way to prove it is drug fever is to re-challenge, which, since it is not an allergic reaction, you can do safely, but is rarely needed. The rare time there is re-challenge has occurred when there is a change of housestaff and they inadvertently restart the medication. Oops.
After stopping the antibiotics her fever curve drifted down over 48 hours. Probably the vancomycin. He shoots. He scores. No fever for 48 hours, then, just to piss me off, she has a fever. Just one, that doesn’t recur. It was a mustache on the Mona Lisa of my diagnosis.
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Drug fever. Infect Dis Clin North Am. 1996 Mar;10(1):85-91. Review.
PMID: 8698996
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