2026 data ClinicalTrials.gov official source

Conditions: C

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

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

2,954 conditions starting with "C"

Showing 1,651–1,700 of 2,954

Condition	Trials	Recruiting
Circadian Rhythm	10	9
Circadian Rhythm Disorders	8	2
Circadian Rhythm Sleep Disorder	1	-
Circadian Rhythm Sleep Disorder of Shift Work Type	2	2
Circadian Rhythm Sleep Disorder, Shift Work Type	3	-
Circadian Rhythm Sleep Disorder, Unspecified	1	1
Circadian Rhythm Sleep Disorders	1	-
Circadian Rhythm Sleep-Wake Disorders, Shift Work Type	1	1
Circadian Rhythms	3	3
Circulating Biomarkers	2	1
Circulating Tumor Cells	3	1
Circulating Tumor DNA	2	1
Circulatory Stress	1	-
Circumcision	1	-
Circumcision, Male	1	-
Circumference Reduction	1	-
Cirrhosis	54	29
Cirrhosis Advanced	2	1
Cirrhosis Alcoholic	2	1
Cirrhosis Cryptogenic	1	-
Cirrhosis Due to Hepatitis B	2	1
Cirrhosis Due to Hepatitis C	2	1
Cirrhosis Early	2	1
Cirrhosis Infectious	2	1
Cirrhosis of the Liver	1	-
Cirrhosis, Biliary	1	-
Cirrhosis, Liver	35	21
Citrin Deficiency	1	-
Citrullinemia 1	2	2
CJD (Creutzfeldt Jakob Disease)	1	1
CKD	5	1
CKD Associated With Type 1 Diabetes	1	-
CKD Stage 3	1	1
CKD Stage 3/4	1	-
CKD Stage 4	1	1
CKD Stage 5	1	-
CKD-MBD	1	1
CLARITHROMYCIN/DILTIAZEM [VA Drug Interaction]	1	-
Class IV Angina	1	-
Class V Non-carious Cervical Dental Lesions	1	-
Classic Congenital Adrenal Hyperplasia	3	3
Classic Congenital Mesoblastic Nephroma	1	-
Classic Follicular Lymphoma	2	1
Classic Hodgkin Lymphoma	10	3
Classical Hodgkin Lymphoma	9	4
Classical Hodgkin Lymphoma Recurrent	1	-
Classical Hodgkin Lymphoma Refractory	1	-
Classical Hodgkin's Lymphoma	1	-
Claudication	5	4
Claudication, Intermittent	3	3

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