What should you know about cat hives?

Hives, also called urticaria, appear as raised bumps or plaques that may be pink, pale, or difficult to see beneath fur. They can develop after an insect bite, medicine, food exposure, contact irritant, or another trigger, although the cause is not always obvious. Individual welts may fade and reappear while new ones form. [Itchy Skin](/symptoms/itchy-skin/), [Skin Rash](/symptoms/skin-rash/), and [Skin Swelling](/symptoms/skin-swelling/) are useful descriptions, but they do not establish the cause. A veterinarian will assess the timing, distribution, and overall condition.

Remove access to a suspected new food, product, plant, or medication and note when the welts appeared. Do not give a human antihistamine or pain medicine without veterinary instructions. A clinician may recommend an [Antihistamine Treatment](/treatments/medical-dermatology/oral-antihistamine-therapy/) or another option based on the cat’s weight, health, and trigger. Keep the cat from scratching if possible, and take a photograph because welts may change before the appointment. Avoid bathing with fragranced products while the skin is reactive.

Seek emergency veterinary help if hives occur with swelling of the face, lips, tongue, or throat; noisy or difficult breathing; repeated vomiting; collapse; pale gums; or extreme weakness. These signs can indicate a severe allergic reaction and should not be monitored at home. Prompt assessment is also appropriate when welts persist, recur, or follow a new medicine. [Angioedema](/conditions/angioedema/) describes deeper swelling that can accompany an allergic reaction.

Ask what exposures could fit the timing, whether the medicine or food list should change, and which signs require immediate return. Confirm the correct dose and formulation of any treatment, and ask whether a follow-up examination is needed if the welts recur.