open-label trial

{{Short description|Research study in which both the researcher and the participant know which treatment is being used}}

An open-label trial, or open trial, is a type of clinical trial in which information is not withheld from trial participants.{{cite web

|url=https://www.cancer.gov/publications/dictionaries/cancer-terms/def/open-label-study

|title=Open label study|publisher=National Cancer Institute, US National Institutes of Health|date=2020|access-date=20 November 2020}} In particular, both the researchers and participants know which treatment is being administered. This contrasts with a double-blinded trial, where information is withheld both from the researchers and the participants to reduce bias.{{cite web |title=Double-blind (trial) |url=https://www.merriam-webster.com/dictionary/double-blind |publisher=Merriam-Webster Medical Dictionary |access-date=20 November 2020 |date=2020}}{{cite web |title=Double-blind study |url=https://clinicalinfo.hiv.gov/en/glossary/double-blind-study |publisher=HIV.gov, Office of AIDS Research, US National Institutes of Health |access-date=20 November 2020 |date=2020}}

Open-label trials may be appropriate for comparing two similar treatments to determine which is most effective, such as a comparison of different prescription anticoagulants,{{cite journal | last1=Beyer-Westendorf | first1=J. | last2=Buller| first2=H. | title=External and internal validity of open label or double-blind trials in oral anticoagulation: better, worse or just different? | journal=Journal of Thrombosis and Haemostasis | volume=9 | issue=11 | year=2011 | issn=1538-7933 | doi=10.1111/j.1538-7836.2011.04507.x | pages=2153–2158| pmid=21920015 | doi-access=free }} or possible relief from symptoms of some disorders when a placebo is given.{{cite journal | last1=Ballou | first1=Sarah | last2=Kaptchuk | first2=Ted J. | last3=Hirsch | first3=William | last4=Nee | first4=Judy | last5=Iturrino | first5=Johanna | last6=Hall | first6=Kathryn T. | last7=Kelley | first7=John M. | last8=Cheng | first8=Vivian | last9=Kirsch | first9=Irving | last10=Jacobson | first10=Eric | last11=Conboy | first11=Lisa | last12=Lembo | first12=Anthony | last13=Davis | first13=Roger B. | title=Open-label versus double-blind placebo treatment in irritable bowel syndrome: study protocol for a randomized controlled trial | journal=Trials | volume=18 | issue=1 | date=25 May 2017 | page=234 | issn=1745-6215 | doi=10.1186/s13063-017-1964-x | pmid=28545508 | pmc=5445390 | doi-access=free }}

An open-label trial may still be randomized. Open-label trials may also be uncontrolled (without a placebo group), with all participants receiving the same treatment.