Temperature in allergies

Can there be a temperature with an allergy? And if so, what is the reason for the increase in temperature, because an allergy is not an infectious inflammation, but an immune response of the body.

As part of the immune response to a particular trigger antigen, this reaction is caused by the accumulation of IgE antibodies on the membranes of sensitized mast cells and basophils and an increased release from them of an immunostimulating nitrogenous compound - the tissue mediator histamine, which binds to the G protein of histamine H1 receptors.

Causes allergy fever

Researchers have concluded that the causes of fever due to allergies are rooted in histamine.

Although the key role of this biogenic amine is as a mediator of pruritus (skin itching), in fact it is present in all cells of the body and participates in more than two dozen different physiological functions, including the inflammatory response. By increasing the permeability of capillaries for leukocytes and phagocytes, histamine enables them to enter the inflammation site and begin neutralizing pathogenic bacteria in infected tissues.

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Risk factors

The main risk factors for fever during allergies are the addition of an infection of any localization and the parallel development of an infectious inflammatory process. This is especially common for fever during allergies in children. Therefore, you should pay attention to the symptoms that appear simultaneously and are not typical for allergic diseases: possible nausea, abdominal pain below the navel or in the hypochondrium, dry mouth, dizziness, etc. It should also be borne in mind that in young children, fever can be caused by an allergy to insect bites, to the introduction of vaccines during preventive vaccinations.

According to allergists, high temperature in adults with allergies is often associated with the consumption of products (food allergies, including products with sodium glutamate and food colorings) or the intake of certain medications that suppress the activity of enzymes that ensure the cyclic biotransformation of histamine. The fact is that in a healthy person, histamine is constantly broken down by the enzymes diamine oxidase and histamine-N-methyltransferase. Diamine oxidase is synthesized by the cells of the intestinal mucosa, and if the functions of the intestine are impaired by taking some medication, then the metabolism of histamine by oxidative deamination is disrupted. In particular, an increase in temperature due to an increase in the amount of unsplit histamine can be caused by an allergy to aspirin, acetylcysteine, ambroxol, beta-lactam antibiotics of the cephalosporin group, diazepam (Valium), verapamil, naproxen, radiocontrast agents, etc.

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Pathogenesis

The pathogenesis of fever in allergies is explained by the fact that histamine also acts as a neurotransmitter of the central nervous system, and neurons containing histamine are concentrated in the tubermammillary nuclei of the hypothalamus. This ensures the participation of histamine in the sleep-wake cycle (it is responsible for wakefulness), regulation of nociceptive sensitivity (physical pain) and appetite, endocrine homeostasis and body temperature (through the hypothalamic thermoregulation centers).

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Symptoms

The symptoms caused by increased histamine levels depend on where it is released and what receptors it binds to. Thus, histamine promotes increased capillary permeability, causing tissues to become overdried with fluid and swell. And histamine-associated sensory stimulation of the nerve endings of the mucous membranes leads to classic symptoms of an allergic reaction - sneezing, runny nose and watery eyes. So, subfebrile temperature during allergies can appear briefly during pollinosis, that is, hay fever or seasonal allergies. Most often, a change in temperature towards an increase occurs at the height of an allergy to poplar fluff or blooming ragweed.

Low temperature due to allergies

A low temperature is also possible with allergies. The release of histamine by endothelial cells (the inner lining of blood vessels) with allergies leads to an increase in nitric oxide levels, hyperpolarization of endothelial cell membranes, and vasodilation - relaxation of the muscle fibers of the vascular walls and dilation of blood vessels. As a result, blood pressure drops sharply (by 30% below standard values), and these may be the first signs of developing anaphylactic shock, which also includes symptoms such as increased or decreased heart rate, shortness of breath (the result of bronchospasm), wheezing and stridor (whistling breathing), swelling of the tongue and throat, pale skin (with cyanosis), cold sweat, dizziness, loss of consciousness.

Diagnostics allergy fever

If the patient suffers from allergies, the diagnosis of temperature in allergies should be carried out by his attending allergist. If a person doubts whether he has an allergy, he should still go to an allergist.

See more about how Allergy Diagnostics is performed, as well as How to get tested for allergies

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Differential diagnosis

It is difficult to overestimate the responsibility of the doctor who carries out differential diagnostics of temperature in case of an allergic reaction of the body and temperature, the increase of which is associated with an inflammatory process of bacterial etiology. Therefore, additional examination of the patient with the involvement of specialists in infectious diseases, an otolaryngologist, a phthisiologist, a gastroenterologist, as well as instrumental diagnostics (X-ray, ultrasound, etc.) may be required.

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Treatment allergy fever

Once again, we emphasize that any treatment, including treatment for fever due to allergies, is prescribed by a doctor.

Considering that the allergic reaction is caused by the activity of histamine, most often prescribed drugs are antihistamines, which block the binding of histamine to H1 receptors.

Loratadine (Claritin, Clargotil, Lotaren and other trade names) acts quickly, and its therapeutic effect lasts for 24 hours. Therefore, the dose for adults and children aged 12 years and older is 10 mg once a day (i.e. one tablet), and children under this age weighing less than 30 kg should be given half a tablet per day. It is better to give a child under two years of age the drug in the form of syrup.

Side effects include a feeling of dry mouth and, in rare cases, vomiting. It is not advisable for pregnant women to use antihistamines, and they are contraindicated in the first trimester.

Hifenadine (Fenkarol) in tablets of 25 mg is prescribed to adults one or two tablets three times a day; children over 12 years old - one tablet up to three times a day; children 7-12 years old - half a tablet, 3-7 years old - 20 mg per day (divided into two doses). Side effects and contraindications are identical to Loratadine.

Cetirizine (Cetrin, Zyrtec) is available in tablets (10 mg) - for adult patients and children 12 years and older. You can take one tablet once a day or ½ a tablet twice a day (with an interval of 8-9 hours). For children 2-6 years old, there are drops that are taken once a day (10 drops). In addition to dry mouth, there may be side effects in the form of headache, dizziness, increased drowsiness or excitability. In addition to pregnancy, the list of contraindications for Cetirizine includes renal failure.

Levocetirizine (Glenzet, Cetrilev, Aleron) - 10 mg tablets - like Loratadine, should be taken once a day (one tablet). This medicine is not prescribed to children under six years of age, with kidney problems and during pregnancy and breastfeeding. The use of this drug can lead to nausea and vomiting, dry mouth and itchy skin, increased appetite and abdominal pain.

In cases where inflammation of an infectious nature is diagnosed (causing an increase in temperature in the presence of allergies in patients), treatment is carried out by the appropriate specialist with the prescription of the necessary medications.

Complications and consequences

Allergy-related anaphylactic shock (ICD-10 code T78.2), a rapid systemic reaction to bee, wasp, triatomine bug stings, or idiopathic anaphylactic shock is a life-threatening condition with serious consequences and complications. Anaphylaxis requires emergency medical care, including resuscitation. The lifetime risk of recurrence of such a reaction is 0.05-2%. Anaphylaxis caused by pharmacological drugs is most often fatal.

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Prevention

Prevention of fever due to allergies is not covered in medical literature: obviously, such methods simply do not exist today.

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Forecast

The prognosis (excluding the risk of developing anaphylactic shock) will depend on the timely detection of the allergy, its correct treatment and the elimination of the allergen's effect on the body.