What medications are used to treat hives and itching in an emergency room setting?

From the Guidelines

In an emergency room setting, the first-line treatment for hives and itching typically involves the administration of epinephrine for severe cases, followed by adjunctive therapy with H1 antihistamines such as diphenhydramine 25-50mg IV or orally, and corticosteroids like methylprednisolone 125mg IV or prednisone 40-60mg orally to reduce inflammation. The choice of medication depends on the severity of the symptoms and the presence of any underlying conditions. According to the most recent guidelines, antihistamines and glucocorticoids should not be administered before, or in place of, epinephrine in cases of anaphylaxis 1.

Treatment Options

• H1 antihistamines: diphenhydramine (Benadryl) 25-50mg IV or orally, or second-generation antihistamines like cetirizine 10mg or loratadine 10mg orally for less sedating effects
• Corticosteroids: methylprednisolone 125mg IV or prednisone 40-60mg orally to reduce inflammation
• Epinephrine: 0.3-0.5mg IM (1:1000 solution) for anaphylaxis or severe angioedema
• H2 blockers: famotidine 20mg IV or ranitidine 50mg IV as adjunctive therapy

Rationale

The use of antihistamines and glucocorticoids in the treatment of anaphylaxis is supported by the fact that they can help alleviate cutaneous signs and symptoms, such as pruritus, flushing, and urticaria 1. However, epinephrine remains the first-line treatment for anaphylaxis due to its rapid onset of action and ability to reverse life-threatening symptoms. The addition of antihistamines and glucocorticoids can help reduce the risk of symptom recurrence and improve patient outcomes. It is essential to note that the use of glucocorticoids in the acute management of anaphylaxis is limited due to their slow onset of action, and their benefits are more pronounced in reducing the length of hospital stay rather than preventing return visits to the ED 1.

Monitoring and Follow-up

Patients should be monitored for drowsiness with diphenhydramine and may need a short course of oral antihistamines (3-5 days) after discharge to prevent symptom recurrence. Education on avoidance of allergens and follow-up with a primary care physician or allergist is also crucial in managing patients with hives and itching 1.

From the FDA Drug Label

INDICATIONS AND USAGE: Diphenhydramine hydrochloride in the injectable form is effective in adults and pediatric patients, other than premature infants and neonates, for the following conditions when diphenhydramine hydrochloride in the oral form is impractical Antihistaminic For amelioration of allergic reactions to blood or plasma, in anaphylaxis as an adjunct to epinephrine and other standard measures after the acute symptoms have been controlled, and for other uncomplicated allergic conditions of the immediate type when oral therapy is impossible or contraindicated. ADRENALIN (epinephrine injection) 1 mg/mL, for intramuscular and subcutaneous use Initial U. S. Approval: 1939 RECENT MAJOR CHANGES Indications and Usage, Mydriasis (1) Removed 09/2016 Dosage and Administration (2) 05/2016,09/2016 Warnings and Precautions (5.1,5. 2) 05/2016,09/2016 INDICATIONS AND USAGE Adrenalin® is a non-selective alpha and beta adrenergic agonist indicated for: Emergency treatment of allergic reactions (Type 1), including anaphylaxis ( 1)

The medications used to treat hives and itching in an emergency room setting are:

• Diphenhydramine (IV): an antihistamine used for the amelioration of allergic reactions, including anaphylaxis, as an adjunct to epinephrine and other standard measures 2
• Epinephrine (IM): a non-selective alpha and beta adrenergic agonist indicated for emergency treatment of allergic reactions, including anaphylaxis 3

From the Research

Medications for Hives and Itching in Emergency Room Settings

Medications used to treat hives and itching in emergency room settings include:

• Antihistamines, such as diphenhydramine and cetirizine, which are commonly used to relieve symptoms of acute urticaria and allergic reactions 4, 5, 6
• Corticosteroids, which may be used in combination with antihistamines to treat anaphylaxis and other severe allergic reactions 7
• Epinephrine, which is the first-line treatment for anaphylaxis and is often administered in emergency room settings 7

Comparison of Medications

Studies have compared the efficacy of different medications for treating hives and itching, including:

• A study that found intravenous cetirizine to be an effective alternative to intravenous diphenhydramine for treating acute urticaria, with benefits of less sedation and fewer adverse events 4
• A study that found diphenhydramine to be more effective than cimetidine for treating pruritus from acute allergic reactions, while the combination of cimetidine and diphenhydramine was more effective for treating acute urticaria 5
• A study that found oral fexofenadine to have a similar onset of action to oral and intramuscular diphenhydramine for reducing histamine-induced wheal-and-flare responses, despite its perceived slower onset of action 6

H2-Receptor Antagonists for Urticaria

H2-receptor antagonists, such as ranitidine and cimetidine, have been studied as potential treatments for urticaria, with some evidence suggesting that they may be effective in combination with antihistamines:

• A review of four studies found that a combination of ranitidine with diphenhydramine was more effective at improving the resolution of urticaria than diphenhydramine alone, while cimetidine provided no statistically significant greater overall improvement in symptoms of urticaria when compared to diphenhydramine 8