An antipyretic (/ˌæntipaɪˈrɛtɪk/, from anti- 'against' and pyretic 'feverish') is a substance that reduces
fever.[1] Antipyretics cause the
hypothalamus to override a
prostaglandin-induced increase in
temperature. The body then works to lower the temperature, which results in a reduction in fever.
Most antipyretic medications have other purposes. The most common antipyretics in the US are usually
ibuprofen and
aspirin, which are
nonsteroidal anti-inflammatory drugs (NSAIDs) used primarily as
anti-inflammatories and
analgesics (pain relievers), but which also have antipyretic properties; and
paracetamol (acetaminophen), an analgesic without anti-inflammatory properties.[2]
There is some debate over the appropriate use of such medications, since fever is part of the body's
immune response to infection.[3][4] A study published by the
Royal Society claims that fever suppression causes at least 1% more
influenza deaths in the United States, or 700 extra deaths per year.[5]
Non-pharmacological treatment
Bathing or sponging with lukewarm or cool water can effectively reduce body temperature in those with
heat illness, but not usually in those with fever.[6] The use of alcohol baths is not an appropriate cooling method, because there have been reported adverse events associated with systemic absorption of alcohol.[7]
Medications
The list of medications with antipyretic effects includes many common drugs that also have analgesic and anti-inflammatory activity, several of which are commonly sold
over-the-counter (OTC).
NSAIDs (non-steroidal anti-inflammatory drugs), a broad class of medications that in addition to their defining effect of reducing inflammation, also tend to be potent analgesics and antipyretics. The majority work by inhibiting the activity of the
cyclooxygenase (COX) family of enzymes in the body.
Phenazone-like drugs (
pyrazolones), many of which have been largely phased out of used owing to safety concerns in most countries (including
metamizole, banned in over 30 countries for causing
agranulocytosis), but remain available in some locations or for specific purposes such as for treating
otitis media in the form of
ear drops.
Paracetamol (acetaminophen) class antipyretics, which have negligible anti-inflammatory activity. Apart from paracetamol itself, the medications in this class are mainly previously marketed drugs which were withdrawn owing to safety concerns, one example of this being
phenacetin.
A few other medications have antipyretic effects of varying strength. While these medications tend to have too weak fever reducing effects or too many adverse effects to use primarily as antipyretics, their antipyretic effect may occasionally be useful. For example, there are theoretical reasons to believe,[10] as well as slight evidence from one human trial,[11] that
α2-adrenergic agonists, and particularly
clonidine (a common drug used to treat
high blood pressure,
ADHD,
spasticity and several other conditions), may have antipyretic effects, which if verified could potentially be useful in patients with
septic shock or
acute respiratory distress syndrome.[12]
Use in children
The U.S.
Food and Drug Administration (FDA) notes that improper dosing is one of the biggest problems in giving
acetaminophen (paracetamol) to children.[13] The effectiveness of acetaminophen alone as an antipyretic in children is uncertain, with some evidence showing it is no better than physical methods.[14] Therapies involving alternating doses of acetaminophen and
ibuprofen have shown greater antipyretic effect than either drug alone.[15] One meta-analysis indicated that ibuprofen is more effective than acetaminophen in children at similar doses when both are given alone.[16]
Due to concerns about
Reye syndrome, it is recommended that aspirin and
combination products that contain aspirin not be given to children or teenagers during episodes of fever-causing illnesses.[17][18]
Traditional medicine
Traditional use of
vascular plants with antipyretic properties is a common worldwide feature of many
ethnobotanical cultures. In ethnobotany, a plant with naturally occurring antipyretic properties is commonly referred to as a febrifuge.[19]
^Mokhtari M, Sistanizad M, Farasatinasab M (January 2017). "Antipyretic Effect of Clonidine in Intensive Care Unit Patients: A Nested Observational Study". J Clin Pharmacol. 57 (1): 48–51.
doi:
10.1002/jcph.776.
PMID27264198.
S2CID3741978.
^Kauffman, Ralph; Sawyer, L.A.; Scheinbaum, M.L. (1992). "Antipyretic Efficacy of Ibuprofen vs Acetaminophen". American Journal of Diseases of Children. 146 (5): 622–625.
doi:
10.1001/archpedi.1992.02160170102024.
PMID1621668.
^Schultes, Richard Evans; Raffauf, Robert F. (1994). "De Plantis Toxicariis e Mundo Novo Tropicale Commentationes XXXIX Febrifuges of northwest Amazonia". Harvard Papers in Botany. 1 (5): 52–68.
ISSN1043-4534.
JSTOR41761491.
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