Fever that begins after taking a medication or receiving an immunization

Some medications can cause a fever. Medications that are most likely to cause a fever include:

• Amphetamines, such as Ritalin.
• Antibiotics, such as sulfonamides, penicillins, cephalosporins, or tetracyclines.
• Antidepressants, such as monoamine oxidase inhibitors (MAOIs).
• Antifungals, such as Lotrimin.
• Antihistamines, such as Benadryl.
• Antipsychotics, such as phenothiazine.
• Barbiturates, such as phenobarbital.
• Chemotherapy medications.
• Heart medications, such as methyldopa, procainamide, or quinidine.
• Iodines.
• Seizure medications, such as Dilantin.

Sometimes a fever occurs within a week after you start taking a new medication. A rash may or may not occur with the fever. If a fever occurs following the start of a new medication, call your health professional to discuss your symptoms before taking your next dose. The medication may need to be stopped or changed, or the dose may need to be adjusted.

A rash and hives that develop without fever after you start taking a new medication may indicate that you are having an allergic reaction to the medication. Report your symptoms to your health professional before taking your next dose.

Some immunizations may cause a fever within 3 weeks of the immunization. If your health professional has given you instructions on how to treat your fever after an immunization, follow those instructions. If your fever continues despite home treatment, report your symptoms to your health professional.

If a fever occurs after you take a nonprescription medication, stop taking it. If you feel you need to continue taking the medication, call your health professional to discuss it.