Drug Fever
A fever caused by a medication, not an infection
Quick Facts
- Type: Adverse drug reaction
- Cause: A medication, not infection
- Key clue: Fever with no clear infection source
- Main treatment: Stopping the responsible drug
Overview
Drug fever is a rise in body temperature caused by a medication rather than by an infection or other illness. It is a recognized but easily missed adverse drug reaction, because fever is so often assumed to mean infection. In drug fever, the temperature is linked to taking a particular medicine and typically settles once that medicine is stopped.
Drug fever can occur with many different medications and may appear on its own or alongside other signs of a drug reaction, such as a rash. Recognizing it matters because, if it is not identified, people may undergo extra tests or receive more medicines while the real cause continues. The key step is to consider medications as a possible source of an unexplained fever. This can be especially tricky in the hospital, where someone may be receiving several medicines and also being treated for an infection, making it hard to tell whether a continuing fever is from the illness or from a drug. Keeping drug fever in mind helps avoid unnecessary testing and lets the real cause be addressed.
Symptoms
The main feature is fever, which can be low-grade or high. Other symptoms may or may not be present.
- Fever, sometimes with chills or sweats
- Often feeling relatively well despite the fever
- Sometimes a skin rash
- Headache or muscle aches in some cases
- No clear source of infection on evaluation
A helpful clue is fever that appears after starting a new medication and has no obvious infectious cause. However, fever can be serious, so high fever, confusion, difficulty breathing, a spreading rash with blistering, or feeling very unwell should be evaluated urgently to rule out infection or a severe reaction.
Causes
Many medicines can cause drug fever through several mechanisms, such as an immune reaction or a direct effect of the drug.
- Antibiotics: A number of antibiotics are recognized causes.
- Seizure medicines and certain other drugs: Some can trigger fever, at times with a rash.
- Heart and blood pressure medicines: Certain ones are associated with fever.
- Other medications: Including some used for gout, infections, and other conditions.
Drug fever can begin days to weeks after starting a medicine, and sometimes after a person has been taking it for a long time, which can make the link harder to spot.
Risk Factors
- Starting a new medication, especially antibiotics
- Taking several medications at once
- A previous drug reaction
- Being in the hospital, where many medicines may be given
Diagnosis
Drug fever is largely a diagnosis of exclusion, made after other causes of fever are ruled out.
- Careful history: Reviewing all medications and their timing in relation to the fever.
- Tests for infection: Blood tests, urine tests, cultures, and imaging to look for an infectious or other cause.
- Looking for other reaction signs: Such as a rash or changes in blood test results.
- Response to stopping the drug: The fever usually resolves within a few days of stopping the responsible medicine, which strongly supports the diagnosis.
Treatment
The main treatment is identifying and stopping the responsible medication, under medical guidance.
- Stopping the drug: The fever typically clears within a few days after the medicine is discontinued.
- Switching medicines: When the medication is still needed, a doctor chooses a suitable alternative.
- Supportive care: Fluids, rest, and fever-reducing measures as advised.
- Monitoring: Watching for other signs of a drug reaction and confirming the fever resolves.
It is important to record the responsible medicine so it can be avoided in the future, since fever may return more quickly if the drug is taken again.
Prevention
- Keep an up-to-date list of all your medications and supplements
- Tell your healthcare providers about any past drug reaction and which medicine caused it
- Avoid the specific medicine that previously caused a reaction
- Report any new fever after starting a medication so it can be assessed promptly
When to See a Doctor
See a doctor if you develop a fever after starting a new medication, especially if there is no obvious infection. Do not stop prescribed medicines without advice. Seek urgent or emergency care if you have:
- A very high fever
- Confusion, severe headache, or a stiff neck
- Difficulty breathing
- A spreading rash with blistering or peeling skin
- Feeling very unwell or faint
These can signal a serious infection or a severe drug reaction that needs prompt treatment.
Frequently Asked Questions
What is drug fever?
Drug fever is a fever caused by a medication rather than an infection. It is linked to taking a particular medicine and usually resolves within a few days after that medicine is stopped. It is easily missed because fever is often assumed to mean infection.
How do doctors know a fever is from a drug?
Drug fever is mainly a diagnosis of exclusion. Doctors review all medicines and their timing, run tests to rule out infection and other causes, and look for other signs of a drug reaction. The fever resolving after stopping the suspected drug strongly supports it.
Which medications commonly cause drug fever?
Many medicines can, including certain antibiotics, some seizure medicines, and certain heart, blood pressure, and gout medicines. Drug fever can begin days to weeks after starting a medication, and sometimes after long-term use.
How is drug fever treated?
The main treatment is stopping the responsible medication under medical guidance, after which the fever usually clears within a few days. If the medicine is still needed, a doctor chooses a suitable alternative. Supportive care helps in the meantime.
Should I stop my medication if I think it is causing a fever?
Do not stop a prescribed medicine on your own. Contact your doctor, who can assess whether the fever is from infection, the drug, or another cause, and decide safely whether to stop or switch the medication.
References
- MedlinePlus, U.S. National Library of Medicine. Fever.
- National Library of Medicine, StatPearls. Drug Fever.
- Mayo Clinic. Drug allergy and adverse drug reactions.
- Centers for Disease Control and Prevention (CDC). Antibiotic use and side effects.