Drug fever usually occurs in association with medication use as an undesirable side effect. However, in some cases, drug fever is a desirable side effect with therapeutic benefits. An elevated body temperature caused by certain drugs is usually registered up to ten days after the start of therapy. Depending on the triggering drug, drug fever may also occur earlier or later.
What is drug fever?
Drug fever – also called medication fever – is defined as an increase in temperature as a result of taking a medication. The reason for the febrile reaction to the drug is often thought to be an intolerance or allergy to one or more components of the drug. However, the drug can also have an effect on the body’s thermoregulation. This effect may even be intentional in the case of cytostatic drugs. There may also be a thermal effect in drug fever that was triggered by one of the substances contained. In drug fever, allergic or intolerance reactions must be distinguished from substance-related effects. The latter may occur in a dose-dependent manner. If necessary, the drug must be replaced or lowered in dose in drug fever.
Causes
The causes of drug fever may lie in the patient or in the prescribed drug. If the patient is allergic, drug fever can potentially occur in response to any prescribed medication. Drug fever may be a sign of an intolerance reaction, a true allergy, or anaphylactic shock. In the latter case, the drug must be discontinued immediately. If necessary, medical countermeasures must be initiated. In addition, increased sensitivity to (certain) drugs may be congenital. Other causes of drug fever may be due to the drug itself. For example, it may affect thermoregulation and trigger febrile episodes. In the case of a substance-related reaction, the drug does not always have to be discontinued. It is often sufficient to reduce the dose in the case of drug fever. However, it is also possible that the fever has an independent cause and was triggered by an inflammation. If the drug fever does not subside after dosing down or discontinuation of the prescribed preparation, differential diagnostic investigations are necessary. It may then not be drug fever.
Symptoms, complaints, and signs
Typical symptoms and signs of drug fever include elevated body temperature. This occurs with delay after a week or later. Mild fever is possible, but severe febrile effects are also possible. Drug fever may be accompanied by other symptoms and complaints. Depending on the type and trigger of drug fever, there may be a stuffy or runny nose. Spotted fever may be accompanied by sneezing attacks. Drug fever may trigger profuse sweating and unusual pallor of the skin in the patient. There may be noticeable house rashes (exanthema) or hives (urticaria) with corresponding itching and red wheals due to the medication. Dangerous symptoms may be present in mucosal swelling, shortness of breath and asthma-like cough. The digestive tract and intestinal flora can also be attacked by the active drug ingredients. There is occasionally diarrhea, vomiting or colic in addition to drug fever, or a general immune deficiency.
Complications
Possible complications of drug fever include Quincke syndrome. This is an allergic reaction to certain ingredients in the drug. Quincke’s edema is classified as a life-threatening acute case. Typical characteristics of Quincke’s edema are noticeably swollen lips, swollen eyelids and breathing difficulties due to increasing swelling of the airways. This causes asthma-like breathing difficulties in addition to drug fever. Quick action is necessary to prevent the patient from dying. Another emergency that can occur in addition to drug fever is circulatory collapse. Circulatory collapse in drug fever can be signs of anaphylactic shock. The signs are striking pallor, sudden drop in blood pressure, and a significant increase in pulse rate. Again, immediate action is essential. A rather rarely occurring complication is hypersensitivity syndrome (HSS).In medicine, it is also described as “Drug Rash with Eosinophilia and Systemic Symptoms” (DRESS) or “Drug Induced Delayed Multi Organ Hypersensitivity Syndrome” (DIDMOHS). The problem is that the symptoms of hypersensitivity syndrome may not appear until several weeks after the onset of therapy. In addition to drug fever, there is often lymph node swelling and skin rashes all over the body. Severe pharyngitis with ulceration and swelling of the face may occur. Additionally, this condition can take a dramatic course due to organ damage. Due to the rarity of this complication, no one can currently say how often it occurs. Without immediate action, the affected patient will die as a result of liver inflammation. This usually entails liver and kidney failure.
When should you go to the doctor?
Anyone who notices unusual symptoms after taking medication should always go to the attending physician or family doctor. Only they can assess whether the symptoms will pass or whether the drug must be discontinued. It is not advisable to stop taking the prescribed medication on your own. The package inserts of the prescribed medications list the possible side effects and interactions that medications can have. There is often an increased risk of adverse effects such as drug fever in certain patient groups. The treating physicians often do not sufficiently inquire which other preparations the patient regularly takes. As a result, they are often unable to assess what the risks are for drug fever or other adverse reactions. In addition, the patient may be allergic to certain ingredients without his or her knowledge. If slightly elevated body temperature without further symptoms occurs after taking a medication, the affected person should observe the fever. As soon as further symptoms such as skin rashes, respiratory problems, swelling or falling blood pressure are noticed, the doctor must be called. If necessary, the emergency physician should be notified. This may be a crisis requiring treatment or an emergency. Drug fevers are not to be trifled with. The primary care physician/emergency room physician needs to know which drug caused the symptoms.
Diagnosis
Simple medical diagnostic tests include taking blood pressure and temperature. If body temperature is elevated, it depends on how high it is. If the fever is mild, no action may be necessary. But for rising fever levels above 38, it does. In addition to temperature monitoring, questioning and physical examination of the affected person is essential. It must be determined whether or not it is actually drug fever. Other causes for the elevated temperature are conceivable. A blood test provides information on various parameters. In the case of drug fever due to immunologically induced drug intolerance, neutropenia or destruction of white blood cells (agranulocytosis) may occur. In this case, there is high fever. As a result of the lack of white blood cells, a defense weakness develops. This can lead to acute tonsillitis, mouth sores or dangerous blood poisoning. Therefore, after determining the body temperature and the present complaints, all diagnostic means that are useful should be used. Only the attending physician can judge whether the symptoms that have occurred are dangerous or temporary. In any case, close monitoring of the patient is advised in cases of more severe drug fever.
Treatment and therapy
Treatment of drug fever is symptom-based. Mild fever is unlikely to require medical intervention. If necessary, the drug may need to be discontinued or exchanged for a better-tolerated drug. In severe drug fever, a more complex approach is required. It is important to reduce the fever by appropriate measures. The different procedure for the treatment of drug fever applies in particular if further symptoms and complaints are observed. Here, the triggering drug should be discontinued if possible, if it is not vital. It may become problematic to prescribe a substitute drug in the presence of severe drug fever. This could result in further medical problems. If necessary, a clinical stay is advisable in order to monitor the patient closely. This measure is particularly advisable if complications occur.Otherwise, treatment depends on the symptoms present. Whether antihistamines or other measures against allergic reactions must be used is decided by the situation. In the case of dramatic developments, transfer to the intensive care unit becomes necessary. Here, organ functions can be monitored. The patient can be ventilated if necessary. In severe allergic reactions and anaphylactic shock, high doses of epinephrine, antihistamines or corticosteroids are administered to save the patient. Rapid response is crucial. Self-treatment with oral antihistamines endangers the patient’s life because of inadequate dosing.
Outlook and prognosis
If mild, with no other symptoms or complaints, drug fever poses no further danger. If mild drug fever does not resolve on its own after a few days, the physician should be consulted. In general, the prognosis for mild fever is good. The situation may be different if severe drug fever occurs. In particular, if allergic or organic symptoms occur, the prognosis looks much worse. It worsens even more if the person concerned stops taking the drug on his or her own authority, carries out improper self-treatment or does not go to the doctor immediately. If it is suspected that the patient has drug-induced fever, medical advice is indispensable. It improves the prognosis and ensures that drug fever is treated quickly and professionally. In case of high fever levels due to thermal regulation problems, the organism is irreversibly damaged. If the triggering drug cannot be discontinued immediately, the fever is lowered by antipyretic analgesics. Paracetamol or acetylsalicylic acid preparations are suitable. However, it would be better to replace the triggering drug with a drug from another group of active ingredients. The more severe the crisis and the longer it lasts, the worse the cure rate. The mortality rate in anaphylactic shock is alarmingly high. The prognosis for Quincke’s edema can also be very poor if it is not recognized and treated immediately. The same is true for the rarely occurring hypersensitivity syndrome (HSS).
Prevention
One of the important preventive measures against drug fever is to inform the attending physician of any intolerances or allergies that are already known. If an intolerance to certain medications has already occurred, this should be reported. It is also important to inform the attending physician of all medications taken regularly. In this way, possible interactions with other preparations can be ruled out or their effects can at least be observed. Reading and internalizing the package insert is an equally important measure. Here, the patient is informed about what known reactions to the prescribed medication have already occurred and how often they occur. Armed with this information, the patient can begin vigilant self-observation. If some of the side effects and interactions mentioned apply to the patient, the physician must be informed of this. The patient should refrain from unauthorized discontinuation of the preparation due to drug fever. Also, the patient should not arbitrarily stop taking the preparation because of reactions described in the package insert. If there are concerns about certain interactions or side effects, he or she should again consult with the practitioner. It is important to respond immediately to any unusual symptoms. If drug fever occurs, the doctor should be informed immediately.
Follow-up
Medications are used to stop symptoms and bring about recovery. However, sometimes complications such as drug fever occur. Aftercare aims to stop the typical accompanying symptoms. Allergies and intolerances usually cause the elevated temperature. In rare cases, they take on dangerous proportions. Doctors usually diagnose drug fever by taking a temperature. They sometimes also order a blood test. The cause is also investigated during a consultation. If the suspicion is confirmed, the medication is discontinued immediately and replaced by another if necessary. Sometimes, instead of discontinuation, fibers-lowering agents must be administered. The physician documents his diagnosis and informs the patient which drugs he should avoid in the future. The affected person incorporates this fact into his knowledge.The extent to which further scheduled testing becomes necessary depends on the intensity of the drug fever. In practice, further follow-up is usually not required. Patients can only counteract the recurrence of drug fever by not taking certain medications. The substances involved are determined on the basis of the initial diagnosis. In practice, the patient is obliged to cooperate. Before treatment, doctors ask whether there are any problems with medications. Here, possible dangers must be pointed out as a preventive measure.
What you can do yourself
Only in mild courses of drug fever can the affected person take remedial action with his own measures. If there is a suspicion that a particular medication has triggered the fever, consultation with the doctor should be held to be on the safe side. At higher temperatures, trivializing the fever can be dangerous. A healthy lifestyle and diet as well as an intact immune system are good prerequisites for surviving a mild form of drug fever well. People with pre-damaged organs, an intestine contaminated with pathogenic germs or known allergies should strive to monitor their symptoms as closely as possible and have them treated if necessary. Permanent damage from years of alcoholism, drug addiction and other dependencies can make a drug binge much more difficult – even if the addiction itself has already been conquered. It is helpful to strive for a generally healthy lifestyle.
