Irritable Bowel Syndrome (IBS): This condition often presents with constipation and can be associated with skin manifestations like urticaria due to the gut-skin axis, where alterations in gut function can lead to skin symptoms.

Food Allergies or Intolerances: Certain foods can cause both gastrointestinal symptoms like constipation and skin reactions such as urticaria. Common culprits include dairy, gluten, and high FODMAP foods.
Inflammatory Bowel Disease (IBD): Conditions like Crohn's disease and ulcerative colitis can cause constipation (especially if the disease is localized to the colon) and may be associated with extraintestinal manifestations, including skin lesions like urticaria.
Thyroid Disorders: Hypothyroidism is known to cause constipation and can also be associated with skin manifestations, including urticaria, though this is less common.

Systemic Mastocytosis: A condition characterized by the accumulation of mast cells in various tissues, which can lead to both gastrointestinal symptoms (like constipation) and skin manifestations (like urticaria) due to the release of histamine and other mediators.
Eosinophilic Gastroenteritis: A rare condition involving eosinophilic infiltration of the gastrointestinal tract, which can cause constipation among other symptoms, and may also be associated with urticaria due to the systemic nature of eosinophilic disorders.
Parasitic Infections: Certain parasites can cause both gastrointestinal and skin symptoms. For example, giardiasis can lead to constipation and, in some cases, urticaria.

Ehlers-Danlos Syndrome: A group of disorders that affect connective tissues supporting the skin, bones, blood vessels, and many other organs and tissues. While primarily known for skin hyperextensibility and joint hypermobility, gastrointestinal symptoms and urticaria can occur in some subtypes.
Mast Cell Activation Syndrome: A condition characterized by excessive mast cell activity, which can lead to a wide range of symptoms, including gastrointestinal issues like constipation and skin symptoms like urticaria.
Autoimmune Disorders: Certain autoimmune conditions, such as lupus or scleroderma, can present with a wide range of symptoms, including constipation and urticaria, though these would be part of a broader constellation of symptoms.