How long does antihistamine treatment take to work for angioedema?

Angioedema is swelling in deeper skin or tissue, often around the lips, eyelids, hands, or feet. Antihistamines are more useful when histamine is driving the episode, especially when hives and itching occur too. Other mechanisms may respond differently, so ongoing or repeated swelling needs medical assessment rather than repeated self-treatment.

Use the antihistamine and dose advised by a clinician or pharmacist, and check whether it can cause drowsiness before driving. Avoid a suspected trigger when it is clear, and record foods, medicines, stings, or infections around the episode. Do not combine products containing the same ingredient or borrow another person’s prescription.

Call emergency services immediately for swelling of the tongue or throat, trouble breathing, wheezing, difficulty swallowing, faintness, or a rapidly worsening episode. Do not wait to see whether an antihistamine works. Seek prompt medical review for persistent swelling, abdominal pain with vomiting, or episodes that recur without an obvious trigger.

Ask what type of angioedema is suspected, which medicine and dose are appropriate, what emergency plan to follow, and whether any current medicine could be contributing. Ask how to distinguish a mild flare from airway involvement.