Diphenhydramine efficacy in treating urticaria
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Diphenhydramine Efficacy in Treating Urticaria
Diphenhydramine for Acute Urticaria: Symptom Relief and Patient Satisfaction
Diphenhydramine, a first-generation H1-antihistamine, is commonly used to treat acute urticaria. Studies show that it provides significant relief from itching and reduces the intensity of hives in patients with acute urticaria, with most patients reporting improvement after treatment 36. In direct patient feedback, those treated with diphenhydramine reported the highest satisfaction compared to other oral agents, with 86% indicating they would use it again . However, sedation and drowsiness are frequent side effects, occurring in about 43% of patients .
Comparison with Other Antihistamines and Combination Therapies
When compared to H2-antihistamines like cimetidine and famotidine, diphenhydramine is generally as effective or slightly less effective in some measures. For example, cimetidine provided a higher overall perception of improvement (87% vs. 76% for diphenhydramine) and caused less sedation . Famotidine was found to be comparable to diphenhydramine in reducing pruritus and urticaria severity, but diphenhydramine tended to be more effective for itch relief, while famotidine reduced the affected skin area more .
Combining diphenhydramine with H2-antihistamines (such as cimetidine or ranitidine) has been shown to be more effective than diphenhydramine alone for resolving urticaria symptoms in some studies 247. The combination therapy led to greater relief of urticaria, though not necessarily of pruritus, and did not significantly increase sedation compared to diphenhydramine alone 27.
Diphenhydramine Versus Second-Generation Antihistamines
A recent trial comparing intravenous diphenhydramine to intravenous cetirizine (a second-generation antihistamine) found that cetirizine was at least as effective as diphenhydramine for acute urticaria. Cetirizine had advantages of less sedation, fewer adverse events, shorter treatment center stays, and lower rates of return visits . This suggests that while diphenhydramine is effective, second-generation antihistamines may offer similar efficacy with a better side effect profile.
Efficacy in Chronic Urticaria
For chronic urticaria, diphenhydramine appears less effective than some alternatives. In a double-blind crossover study, only 5% of patients achieved total clearing of symptoms with diphenhydramine, compared to 43% with doxepin, a tricyclic antidepressant with antihistaminic properties 110. Partial or total control of symptoms was also much lower with diphenhydramine (10%) than with doxepin (74%) 110. Sedation was more common with diphenhydramine than with doxepin .
Role in Combination and Alternative Therapies
In studies comparing diphenhydramine with other treatments for chronic urticaria, such as levocetirizine or acupoint catgut embedding therapy, diphenhydramine was part of the control regimen and showed similar effectiveness and adverse reaction rates to these alternatives, but with a higher recurrence rate . This suggests that while diphenhydramine can be effective, other therapies may provide longer-lasting benefits.
Conclusion
Diphenhydramine is effective in providing rapid relief of itching and hives in acute urticaria, with high patient satisfaction but frequent sedation. It is less effective for chronic urticaria compared to agents like doxepin. Combination therapy with H2-antihistamines can enhance efficacy for acute urticaria. Second-generation antihistamines like cetirizine may offer similar or better efficacy with fewer side effects, making them a preferable option for many patients.
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