What are antipyretics?
Antipyretic is defined as any active ingredient capable of reducing body temperature during feverish states.
When to use them?
We recall that fever is a physiopathological condition characterized by an abnormal increase in body temperature, independent of any changes in external climatic conditions.
Fever can be interpreted as an adaptive system triggered by the body to reduce microbial multiplication and stimulate the immune response.
| Classification | Value in ° C |
|---|---|
| subfebbrile | 37 - 37.4 |
| low-grade fever | 37.5 - 37.9 |
| moderate fever | 38 - 38.9 |
| high fever | 39 - 39.9 |
| hyperpyrexia | > 40 |
Also for this reason, antipyretics must be used with criterion, reserving the assumption to cases of real necessity. In general, the abuse or misuse of antipyretic drugs can trigger allergic reactions, cause problems in the stomach or liver, conceal unclear symptoms and stifle a mechanism that is still useful for decreasing the virulence of certain pathogens and stimulating the immunological response.
Generally, the use of antipyretics is recommended when the body temperature exceeds 39-40 ° C, possibly accompanying it to physical means: sponging with cold water, for example, have shown a fairly good antipyretic activity.
Antipyretic drugs
In-depth articles: drugs for child's fever - high fever
Paracetamol
The antipyretic drug par excellence is paracetamol (or acetaminophen), an active ingredient in medicinal products registered as Tachipirina ® and Efferalgan ® . Although belonging to the category of NSAIDs (non-steroidal anti-inflammatory drugs), paracetamol: it has a minimal anti-inflammatory effect; has a good antipyretic and analgesic effect; it can also be used by children (under 14 the use of aspirin is instead contraindicated for the risk of Reye's syndrome); has a low risk of drug interactions: it is optimally tolerated at the gastric level.
The antipyretic effect of paracetamol is due to the inhibition of the enzyme cyclooxygenase, with a consequent decrease in the synthesis of PGE2 (a prostaglandin that increases body temperature).
- Especially in children, paracetamol is the first choice antipyretic drug, immediately followed by ibuprofen.
Paracetamol should be used with extreme caution in the presence of liver problems (see details).
NSAIDs as antipyretics
Many other non-steroidal anti-inflammatory drugs, such as ibuprofen, aspirin, nimesulide, ketoprofen, flurbiprofen and niflumic acid belong to the antipyretic category. However, while paracetamol inhibits the cyclooxygenase enzyme only centrally, these medicines are also active at the systemic level; therefore, alongside the antipyretic activity an important anti-inflammatory action. Generally, their use can cause gastro-intestinal disorders (bleeding and ulcers).
Precautions and Side Effects
As anticipated, the use of aspirin for anti-pyretic purposes - in addition to the serious interference with the coagulation mechanisms (attention in case of concomitant use of anticoagulants, or in the presence of coagulation disorders) - is not recommended for under 14 years for the risk of Reye's syndrome (a very serious neurological disease). Also not recommended in the presence of gastritis, peptic ulcer and gastroesophageal reflux disease. There is a greater risk of allergic phenomena and sensitization than using paracetamol (see allergy to salicylates). Not recommended even in the presence of thyrotoxicosis hyperthermia or associated with hyperthyroidism.
| Drug | dosage * |
|---|---|
| Paracetamol | 7-15 mg / kg per os every 4-6 h (2400 mg / day) |
| Ibuprofen | 5-10 mg / kg each day 6-8 h (400-600 mg / day) |
| Acetylsalicylic acid | 6.5 mg / kg / day orally every 6 h (1.5-2 g / day) |
| * general dosage in adults. For the treatment of fever in the child consult the specific article within the site. | |
The same side effects, except for the Rye Syndrome risk, are roughly attributable also to other NSAIDs; propionic acid derivatives (especially Ibuprofen, but also Naproxen and Ketoprofen) are the best tolerated, often used for antipyretic purposes.
Recall that in the case of chicken pox should be avoided taking all non-steroidal anti-inflammatory drugs, with the exception of paracetamol.
The category of antipyretics also includes the so-called pyrazolonics, such as aminophenazone, metamizole (or dipyrone) and propiphenazone, which are less used today because they can produce undesirable effects such as anaphylaxis and blood disorders.
Other antipyretics and combinations
Quinine, the famous active ingredient of cinchona, also has important anti-pyretic properties alongside the known antimalarial action.
There are various medicinal products on the market that combine two or more antipyretic active ingredients; however, it is inadvisable to associate aspirin with another NSAID or to combine two anti-inflammatories. As a rule, doctors tend to advise against these associations, as it makes little sense to use two substances that have the same purpose together at a reduced dosage, also because these communions have not shown a particular therapeutic utility.
Natural antipyretics
In the world of phytotherapy, in addition to plants with an antipyretic effect due to the presence of salicylates (such as the spirea olmaria and willow ), the use of so-called diaphoretics is noted: these are natural remedies capable of stimulating sweating, increasing dispersion thermal with reduced body temperature: this is the case of elderflower and linden flowers.
