The goal of this double-blind, Placebo-controlled Randomized Study is to assess if a single dose of betamethasone in children with febrile adenoviral infection works well in achieving an early fever regulation.

The experimentation is conducted to answer this question: "Can betamethasone help reduce fever more quickly in a child with viral adenovirus infection? "The secondary objective is to assess if the child's overall clinical conditions improve more rapidly (reduced sore throat, quicker return to regular eating) and a reduction in the incidence and duration of hospitalizations.

Adenovirus pharyngitis is a highly febrile illness and tends to last for up to 5-7 days if treated only with antipyretics. Currently, there are no evidence-based effective treatments for this infection. The use of single-dose betamethasone is believed to be effective in significantly reducing the hyper-inflammation that the virus can induce in pediatric patients. However, it is an empirical therapeutic practice used variably because positive clinical experience encourages its prescription but lacks experimental evidence.

The main question at hand is whether the single administration of betamethasone at a dosage of 0.1 mg/kg is truly effective in symptomatic adenoviral infection and whether it can, therefore, reduce the overall fever duration and improve the clinical condition of the children. The study does not involve changes to current clinical practice but aims to demonstrate that this clinical practice, mostly used empirically, is actually based on scientific evidence.

Inclusion Criteria:

• Body Temperature measured with an axillary or ear thermometer >= n 37.5°C, persisting for a minimum of 6 hours and a maximum of 5 days.
• Clinical presentation consistent with pharyngo-tonsillar infection by Adenovirus, including At least one of the following symptoms: pharyngodonidae /asthenia/nausea/vomiting/diarrhea/cough/rhinorrhea/abdominal pain/otalgia and at least one of the following signs: pharyngeal hyperemia with or without pharyngo-tonsillar exudate/inflammation of the upper or lower airways/lymphadenopathy/skin rash.-
• Positive result on the antigen test for Adenovirus performed with the "Biosensor" rapid swab.
• Negative result on the swab for Group A Streptococcus (SBEGA), if deemed necessary following McIsaac criteria
• Informed consent form for participation in the study signed by the parent(s) or legal guardian.

Exclusion Criteria:

• Adequate dosage of betamethasone in the 48 hours prior.
• Underlying chronic illness associated with an increased risk of unusual or severe adenoviral infection.
• Inability to tolerate oral medications.
• Documented allergy or any other known contraindication to Bentelan 0.5mg® medication.-Patients on chronic therapy with anticholinesterases, salicylates, nonsteroidal anti-inflammatory drugs, thiazides, furosemide, amphotericin, xanthines (theophylline), antidiabetic drugs, insulin, cyclosporine, ritonavir, ketoconazole, acetylsalicylic acid, phenytoin, phenobarbital, ephedrine, rifampicin, anticoagulants.
• Subacute or chronic conditions requiring a higher equivalent dose of betamethasone or known primary or secondary adrenal insufficiency.
• Transfer to another hospital for any reason.
• Parents who are unable to understand the proposed study or cannot reliably participate in phone follow-up due to significant language barriers.
• Participation in another study involving an experimental drug within the 30 days prior to and during the current study.

All Individual Participant Data requests should be submitted to the corresponding author for consideration. Access to deidentified participant data may be granted following review, after the publication of major results

Data will be available after 6 months from major results publication and for the following 5 years

Data requests should be submitted to the corresponding author for consideration.

The nurse that will prepare and administer the treatment to the patient won't be masked