The goal of this clinical trial is to learn whether a histamine- and pseudoallergen-restricted diet can help reduce symptoms in people with chronic urticaria. It will also learn whether this diet changes the need for urticaria medication.

The main questions it aims to answer are:

Does the diet lower urticaria activity, including hives and itching?

Does the diet improve disease control and quality of life?

Does the diet change the need for urticaria medication?

Which clinical or laboratory factors may affect response to the diet?

There is no comparison group. Researchers will compare participants' symptoms before and after the diet.

Participants will:

Follow a structured histamine- and pseudoallergen-restricted diet

Continue their usual urticaria treatment as recommended by their doctor

Record or report their urticaria symptoms during follow-up

Visit the clinic for assessment of symptoms, disease control, quality of life, medication use, and laboratory findings.

Chronic spontaneous urticaria in children is a heterogeneous condition characterized by recurrent wheals, angioedema, or both for more than six weeks without a consistent external trigger. Although second-generation H1-antihistamines are the mainstay of treatment, disease activity may persist in some children despite standard care.

Dietary factors, including histamine-rich foods, histamine-releasing foods, and pseudoallergens such as selected additives, preservatives, colorants, and naturally occurring food components, have been proposed as potential aggravating factors in a subset of patients. However, the clinical value of dietary restriction in pediatric chronic spontaneous urticaria remains uncertain, and better evidence is needed to determine whether a time-limited dietary approach provides additional benefit.

This randomized controlled study will evaluate a structured low-histamine and pseudoallergen-free diet as an adjunct to standard guideline-based care in children with chronic spontaneous urticaria. The comparator group will receive standard care with general age-appropriate healthy eating advice, without specific restriction of histamine-rich or pseudoallergen-containing foods during the primary comparison period.

All participants will continue to receive standard clinical care according to current urticaria management principles. Antihistamine treatment will be permitted according to clinical need. The study will also explore whether baseline clinical and laboratory characteristics, including autologous serum skin test status and routine inflammatory markers, are associated with response to the dietary intervention.

Because this is a pediatric dietary study, the dietary intervention will be standardized, time-limited, and implemented with parental guidance. Unnecessary prolonged dietary restriction will be avoided.

IInclusion Criteria:

Children aged 1 to 18 years Diagnosis of chronic spontaneous urticaria Disease duration of at least 6 weeks Presence of active urticaria symptoms at enrollment Ability of the child and/or parent/caregiver to complete symptom and diet follow-up forms Ability and willingness of the family to follow the assigned dietary recommendation Written informed consent from parent or legal guardian Assent from the child when applicable

Exclusion Criteria:

Pure chronic inducible urticaria Urticaria secondary to an identified trigger IgE-mediated food allergy requiring a specific elimination diet Active infection or parasitic disease Oral corticosteroid use within the previous 4 weeks Current or recent biological treatment for chronic urticaria Coeliac disease Inflammatory bowel disease Known systemic mast cell disease Severe chronic systemic disease affecting diet, growth, or follow-up Significant malnutrition or a medical condition requiring a special diet Pregnancy or lactation in postmenarchal adolescents Inability or unwillingness of the child or family to adhere to the assigned dietary recommendation Incomplete follow-up data

Individual participant data will not be publicly shared because of privacy and ethical restrictions related to pediatric clinical data. De-identified data may be considered upon reasonable request and subject to approval by the study investigators and relevant institutional authorities.

Participants, families, and treating clinicians will not be blinded because of the dietary nature of the intervention. Outcome assessment and/or statistical analysis will be performed blinded to group allocation when feasible.