| C. diff See Clostridioides difficile infection |
| C. difficile colitis See Pseudomembranous colitis |
| Clostridioides difficile infection |
| Calciphylaxis |
| Calluses and corns See Corns and calluses |
| Cancer |
| Cancer of unknown origin See Carcinoma of unknown primary |
| Cancer, acute lymphocytic leukemia See Acute lymphocytic leukemia |
| Cancer, anal See Anal cancer |
| Cancer, basal cell See Basal cell carcinoma |
| Cancer, bladder See Bladder cancer |
| Cancer, bone See Bone cancer |
| Cancer, breast See Breast cancer |
| Cancer, carcinoid tumors See Carcinoid tumors |
| Cancer, cervical See Cervical cancer |
| Cancer, chronic lymphocytic leukemia See Chronic lymphocytic leukemia |
| Cancer, chronic myelogenous leukemia See Chronic myelogenous leukemia |
| Cancer, colon See Colon cancer |
| Cancer, endometrial See Endometrial cancer |
| Cancer, esophageal See Esophageal cancer |
| Cancer, eye melanoma See Eye melanoma |
| Cancer, floor of the mouth See Floor of the mouth cancer |
| Cancer, gallbladder See Gallbladder cancer |
| Cancer, gastric See Stomach cancer |
| Cancer, hairy cell leukemia See Hairy cell leukemia |
| Cancer, Hodgkin lymphoma See Hodgkin lymphoma (Hodgkin disease) |
| Cancer, Hurthle cell See Hurthle cell cancer |
| Cancer, inflammatory breast See Inflammatory breast cancer |
| Cancer, kidney See Kidney cancer |
| Cancer, leukemia See Leukemia |
| Cancer, liver See Liver cancer |
| Cancer, lung See Lung cancer |
| Cancer, male breast See Breast cancer in men |
| Cancer, Merkel cell See Merkel cell carcinoma |
| Cancer, mesothelioma See Mesothelioma |
| Cancer, multiple myeloma See Multiple myeloma |
| Cancer, nasopharyngeal See Nasopharyngeal carcinoma |
| Cancer, neuroblastoma See Neuroblastoma |
| Cancer, neuroendocrine See Neuroendocrine tumors |
| Cancer, non-Hodgkin lymphoma See Non-Hodgkin lymphoma |
| Cancer, ovarian See Ovarian cancer |
| Cancer, pancreatic See Pancreatic cancer |
| Cancer, paraneoplastic syndromes See Paraneoplastic syndromes of the nervous system |
| Cancer, prostate See Prostate cancer |
| Cancer, retinoblastoma See Retinoblastoma |
| Cancer, skin See Skin cancer |
| Cancer, soft tissue sarcoma See Soft tissue sarcoma |
| Cancer, squamous cell See Squamous cell carcinoma of the skin |
| Cancer, stomach See Stomach cancer |
| Cancer, testicular See Testicular cancer |
| Cancer, throat See Throat cancer |
| Cancer, thyroid See Thyroid cancer |
| Cancer, uterine See Endometrial cancer |
| Cancer, vagina See Vaginal cancer |
| Cancer, vulvar See Vulvar cancer |
| Cancer, Wilms' tumor See Wilms tumor |
| Candidiasis, oral See Oral thrush |
| Candidiasis, vaginal See Yeast infection (vaginal) |
| Canker sore |
| Carbon monoxide poisoning |
| Carbuncles and boils See Boils and carbuncles |
| Carcinoid syndrome |
| Carcinoid tumors |
| Carcinoma of unknown primary |
| Cardiac arrest, sudden See Sudden cardiac arrest |
| Cardiac ischemia See Myocardial ischemia |
| Cardiogenic shock |
| Cardiomegaly See Enlarged heart |
| Cardiomyopathy |
| Cardiomyopathy, dilated See Dilated cardiomyopathy |
| Cardiomyopathy, hypertrophic See Hypertrophic cardiomyopathy |
| Cardiospasm See Achalasia |
| Cardiovascular disease See Heart diseases |
| Carotid artery disease |
| Carotid artery stenosis See Carotid artery disease |
| Carotid insufficiency See Carotid artery disease |
| Carpal tunnel syndrome |
| CAS See Childhood apraxia of speech |
| Castleman disease |
| Cataracts |
| Cavernous malformations |
| Cavities and tooth decay |
| CDG See Chronic granulomatous disease |
| CDH See Congenital diaphragmatic hernia (CDH) |
| Celiac artery compression See Median arcuate ligament syndrome (MALS) |
| Celiac artery compression syndrome See Median arcuate ligament syndrome (MALS) |
| Celiac axis syndrome See Median arcuate ligament syndrome (MALS) |
| Celiac disease |
| Celiac trunk compression syndrome See Median arcuate ligament syndrome (MALS) |
| CELLO See Barrett's esophagus |
| Cellulite |
| Central auditory processing disorder See Auditory processing disorder |
| Central nervous system vascular malformations |
| Central neurofibromatosis See NF2-related schwannomatosis (neurofibromatosis type 2) |
| Central sleep apnea |
| Cercarial dermatitis See Swimmer's itch |
| Cerebral aneurysm See Brain aneurysm |
| Cerebral palsy |
| Cerebrospinal fluid leak See CSF leak (Cerebrospinal fluid leak) |
| Cerebrovascular accident See Stroke |
| Cerumen impaction See Earwax blockage |
| Cervical cancer |
| Cervical dystonia |
| Cervical osteoarthritis See Cervical spondylosis |
| Cervical pain See Neck pain |
| Cervical spondylosis |
| CF See Cystic fibrosis |
| Chagas disease |
| Charcot-Marie-Tooth disease |
| CHD See Hip dysplasia |
| Chemical dependency See Drug addiction (substance use disorder) |
| Chemo brain |
| Chest pain |
| Chest wall pain See Costochondritis |
| Chiari malformation |
| Chickenpox |
| Chilblains |
| Child abuse |
| Child maltreatment See Child abuse |
| Childhood apraxia of speech |
| Childhood obesity |
| Childhood schizophrenia |
| Cholangiocarcinoma (bile duct cancer) |
| Cholangitis, primary sclerosing See Primary sclerosing cholangitis (PSC) |
| Cholecystitis |
| Cholera |
| Chondrosarcoma |
| Chordoma |
| Chorea, Huntington's See Huntington's disease |
| Choroid plexus carcinoma |
| Chronic acid reflux See Gastroesophageal reflux disease (GERD) |
| Chronic adrenal insufficiency See Addison's disease |
| Chronic compartment syndrome See Chronic exertional compartment syndrome |
| Chronic cough |
| Chronic daily headaches |
| Chronic exertional compartment syndrome |
| Chronic fatigue syndrome See Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) |
| Chronic granulomatous disease |
| Chronic hives |
| Chronic kidney disease |
| Chronic kidney failure See Chronic kidney disease |
| Chronic lymphocytic leukemia |
| Chronic lymphocytic thyroiditis See Hashimoto's disease |
| Chronic myelogenous leukemia |
| Chronic obstructive pulmonary disease(COPD) |
| Chronic pelvic pain |
| Chronic renal failure See Chronic kidney disease |
| Chronic rhinosinusitis See Chronic sinusitis |
| Chronic sinusitis |
| Chronic traumatic encephalopathy |
| Chronic vulvar pain See Vulvodynia |
| Churg-Strauss syndrome |
| Cirrhosis |
| CJD See Creutzfeldt-Jakob disease |
| CKD See Chronic kidney disease |
| Claudication |
| Cleft lip and cleft palate |
| Click-murmur syndrome See Mitral valve prolapse |
| Clinical depression See Depression (major depressive disorder) |
| CLL See Chronic lymphocytic leukemia |
| Clostridioides difficile infection |
| Clostridium difficile infection See Clostridioides difficile infection |
| Clubfoot |
| Cluster headache |
| Coccidioidomycosis See Valley fever |
| Cold allergy See Cold urticaria |
| Cold exposure See Hypothermia |
| Cold sore |
| Cold urticaria |
| Cold, common See Common cold |
| Colic |
| Colitis, ischemic See Ischemic colitis |
| Colitis, microscopic See Microscopic colitis |
| Colitis, pseudomembranous See Pseudomembranous colitis |
| Colitis, ulcerative See Ulcerative colitis |
| Collapsed lung See Atelectasis |
| Collapsed lung See Pneumothorax |
| Colon cancer |
| Colon polyps |
| Colonic ischemia See Ischemic colitis |
| Color blindness |
| Colorectal cancer See Colon cancer |
| Columnar epithelium lined lower esophagus See Barrett's esophagus |
| Coma |
| Common cold |
| Common cold in babies |
| Common variable immunodeficiency |
| Complex regional pain syndrome |
| Complicated bereavement See Complicated grief |
| Complicated grief |
| Compressed nerve See Pinched nerve |
| Compulsive gambling |
| Compulsive hoarding syndrome See Hoarding disorder |
| Compulsive overeating See Binge-eating disorder |
| Compulsive sexual behavior |
| Compulsive stealing See Kleptomania |
| Concussion |
| Condylomata acuminata See Genital warts |
| Congenital adrenal hyperplasia |
| Congenital biliary atresia See Biliary atresia |
| Congenital diaphragmatic hernia (CDH) |
| Congenital heart defects in children |
| Congenital hip dislocation See Hip dysplasia |
| Congenital megacolon See Hirschsprung's disease |
| Congenital mitral valve anomalies |
| Congenital myasthenic syndromes |
| Congenital plagiocephaly See Craniosynostosis |
| Congestive heart failure See Heart failure |
| Conjoined twins |
| Conjunctivitis See Pink eye (conjunctivitis) |
| Constipation |
| Constipation in children |
| Contact dermatitis |
| Conversion disorder See Functional neurologic disorder/conversion disorder |
| Cooley's anemia See Thalassemia |
| COPD |
| Corns and calluses |
| Coronary artery disease |
| Coronary microvascular disease See Small vessel disease |
| Coronavirus disease 2019 (COVID-19) |
| Corticobasal degeneration (corticobasal syndrome) |
| Costochondritis |
| Costosternal chondrodynia See Costochondritis |
| Costosternal syndrome See Costochondritis |
| Cough headaches |
| Cough, chronic See Chronic cough |
| COVID-19 See Coronavirus disease 2019 (COVID-19) |
| COVID-19-associated multisystem inflammatory syndrome in children See Multisystem inflammatory syndrome in children (MIS-C) |
| Crabs See Pubic lice (crabs) |
| Cradle cap |
| Cramp, muscle See Muscle cramp |
| Cranial arteritis See Giant cell arteritis |
| Craniopharyngioma |
| Craniosynostosis |
| Creutzfeldt-Jakob disease |
| Crib death See Sudden infant death syndrome (SIDS) |
| Crohn's disease |
| Croup |
| CRPS See Complex regional pain syndrome |
| Cryptorchidism See Undescended testicle |
| CSF leak (Cerebrospinal fluid leak) |
| CTCL See Cutaneous T-cell lymphoma |
| Curvature of the penis See Peyronie's disease |
| Curvature of the spine See Scoliosis |
| Cushing syndrome |
| Cutaneous B-cell lymphoma |
| Cutaneous T-cell lymphoma |
| Cutting/self-injury See Self-injury/cutting |
| CVA See Stroke |
| CVID See Common variable immunodeficiency |
| Cyclic vomiting syndrome |
| Cyclothymia (cyclothymic disorder) |
| Cyclothymic disorder See Cyclothymia (cyclothymic disorder) |
| Cyst, Bartholin's See Bartholin's cyst |
| Cyst, ganglion See Ganglion cyst |
| Cyst, ovarian See Ovarian cysts |
| Cyst, pancreatic See Pancreatic cysts |
| Cyst, pilonidal See Pilonidal cyst |
| Cyst, spermatic See Spermatocele |
| Cystic fibrosis |
| Cystitis |
| Cystitis, interstitial See Interstitial cystitis |
| Cystocele See Anterior vaginal prolapse (cystocele) |
| Cysts, epidermoid See Epidermoid cysts |
| Cysts, sebaceous See Epidermoid cysts |
| Cytomegalovirus (CMV) infection |
| Cytomegalovirus infection See Cytomegalovirus (CMV) infection |
