* The prevalence of AA in the United States, between 1971 and 1974, varied from 0.1% to 0.2% of the population.9 Some works have estimated that about 1.7% of the population presents at least one episode of AA during their life. [http://www.scielo.br/pdf/abd/v80n1/en_v80n01a09.pdf Source]
==Clinical and drug Drug trials=====Clinical Trials==The format for each of the following is:* The name of the trial,* followed by whether the trial is recruiting patients,** The trial may not have started and not yet recruiting, or the trial may have started and do not need any more recruitements, or the trial may be completed.**Note**: Please follow the link to determine the current trial status.* followed by a list of drug/s, if any, used in the trial
* [http://clinicaltrials.gov/ct/show/NCT00069589 Alopecia Areata Registry] - This study is currently recruiting patients (Current: 23 Nov 2006)
* [http://clinicaltrials.gov/ct/show/NCT00176969 Response of Topical Capsaicin in Alopecia Areata] - This study has been completed (Current: 23 Nov 2006) - Capsaicin
* [http://clinicaltrials.gov/ct/show/NCT00177021 Aldara for the Treatment of Extensive Alopecia Areata] - This study has been completed (Current: 23 Nov 2006) - Aldara Cream 5%
* [http://clinicaltrials.gov/ct/show/NCT00177073 Alopecia Areata Registry and Immunogenetic Mechanisms] - This study is currently recruiting patients (Current: 23 Nov 2006) ---- ===Drug Trials=== The format for each of the following is:* The drug,* followed by the name of the trial,* followed by whether the trial is recruiting patients,** The trial may not have started and not yet recruiting, or the trial may have started and do not need any more recruitements, or the trial may be completed.** Note**: Please follow the link to determine the current trial status. '''ClinicalTrials.gov has listed the following drugs in trials for Alopecia Areata:''' <nowiki>*</nowiki> Aldara Cream 5% - [http://clinicaltrials.gov/ct/show/NCT00177021 Aldara for the Treatment of Extensive Alopecia Areata] - This study has been completed (Current: 23 Nov 2006) <nowiki>*</nowiki> Aldara Cream 5% - [http://clinicaltrials.gov/ct/show/NCT00176943 Characteristics of T Cells From Alopecia Areata Scalp Skin Before and After Treatment With Aldara 5%] - This study has been completed (Current: 23 Nov 2006) <nowiki>*</nowiki> Alefacept - [http://clinicaltrials.gov/ct/show/NCT00167102 Alefacept in Patients With Severe Scalp Alopecia Areata] - This study is currently recruiting patients (Current: 23 Nov 2006) <nowiki>*</nowiki> Bimatoprost (Lumigan) - [http://clinicaltrials.gov/ct/show/NCT00187577 Efficacy Study of Latanoprost and Bimatoprost Solutions in Promoting Eyelash Growth in Patients With Alopecia Areata] - This study is no longer recruiting patients (Current: 23 Nov 2006) <nowiki>*</nowiki> Capsaicin - [http://clinicaltrials.gov/ct/show/NCT00176969 Response of Topical Capsaicin in Alopecia Areata] - This study has been completed (Current: 23 Nov 2006) <nowiki>*</nowiki> Hydroxychloroquine - [http://clinicaltrials.gov/ct/show/NCT00176982 Plaquenil for Alopecia Areata, Alopecia Totalis] - This study is currently recruiting patients (Current: 23 Nov 2006) <nowiki>*</nowiki> Latanoprost (Xalatan) - [http://clinicaltrials.gov/ct/show/NCT00187577 Efficacy Study of Latanoprost and Bimatoprost Solutions in Promoting Eyelash Growth in Patients With Alopecia Areata] - This study is no longer recruiting patients (Current: 23 Nov 2006) <nowiki>*</nowiki> Targretin Gel 1% - [http://clinicaltrials.gov/ct/show/NCT00063076 Phase II Randomized Bilateral Comparison of Topical Targretin Gel 1% in Alopecia Areata] - This study is currently recruiting patients (Current: 23 Nov 2006)
==Treatment Approaches==