2026 data ClinicalTrials.gov official source

Conditions: O

Compiled by PlainTrial Editorial, Clinical Trial Intelligence Editorial Team · January 1, 2026

Every condition beginning with O that has a registered US clinical trial, with how many studies cover each.

829 conditions starting with "O"

Showing 201–250 of 829

Condition	Trials	Recruiting
Oligometastatic Prostate Adenocarcinoma	1	1
Oligometastatic Prostate Cancer	1	1
Oligometastatic Prostate Cancer (OMPC)	2	2
Oligometastatic Prostate Carcinoma	7	5
Oligometastatic Renal Cell Carcinoma	2	1
Oligoprogressive	4	4
OligoProgressive Metastatic Disease	2	2
Oligoprogressive Nodal Metastases	1	1
Oligoprogressive Renal Cell Carcinoma	1	-
Oligorecurrence	1	1
Oligospermia	1	1
Oligosymptomatic PSP (oPSP)	1	1
Oligosymptomatic/Variant Progressive Supranuclear Palsy (o/vPSP)	1	-
Olipop	1	1
Olivopontocerebellar Atrophies	1	1
Omega 3 Fatty Acids	2	2
Omega 3 Index	1	-
Omenn's Syndrome	1	-
Onabotulinumtoxin A	1	1
Onchocerciasis	1	1
Oncofertility	1	1
Oncologic Complications and Emergencies	1	1
Oncologic Disease	1	-
Oncologic Surgery	1	1
Oncological Outcomes	1	1
Oncology	25	15
Oncology Patients	3	1
One Eye Blindness	1	-
Oneida Nation Members	2	1
Ongoing or Significant Medical Condition	1	-
Online Intervention	1	1
Online Training for Therapists	1	-
Onychomycosis	12	-
Onychomycosis Due to Trichophyton Mentagrophytes	1	-
Onychomycosis Due to Trichophyton Rubrum	1	-
Onychomycosis of Toenail	2	1
Onychomycosis/Onycholysis and Tinea Pedis	1	-
Oocyte Competence	1	1
Oocyte Cryopreservation	1	1
Oocyte Retrieval and Post Operative Pain Control	1	1
Oophorectomy	1	-
Open Abdomen	1	-
Open Abdominal Surgery	1	1
Open Angle Glaucoma	30	8
Open Angle Glaucoma (OAG)	6	5
Open Angle or Ocular Hypertension	1	-
Open Appendicular Fracture	1	-
Open Bite	1	1
Open Burn Pit Exposure	1	1
Open Dislocation of Ankle	1	1

Data sourced from official public datasets. See our methodology for details.