- Caffeine
- Calcifediol
- Calcitonin-Salmon
- Calcitriol
- Camphor
- Candesartan Cilexetil
- Capreomycin
- Captopril
- Carbachol
- Carbamazepine
- Carbarsone
- Carbenicillin
- Carbidopa
- Carbimazole
- Carbinoxamine
- Carisoprodol
- Carphenazine
- Carteolol
- Carvedilol
- Casanthranol
- Cascara Sagrada
- Cefaclor
- Cefadroxil
- Cefamandole
- Cefatrizine
- Cefazolin
- Cefdinir
- Cefepime
- Cefixime
- Cefmetazole
- Cefonicid
- Cefoperazone
- Ceforanide
- Cefotaxime
- Cefotetan
- Cefoxitin
- Cefpodoxime
- Cefprozil
- Ceftazidime
- Ceftibuten
- Ceftizoxime
- Ceftriaxone
- Cefuroxime
- Celecoxib
- Celiprolol
- Cephalexin
- Cephalothin
- Cephapirin
- Cephradine
- Cerivastatin
- Cetirizine
- Cevimeline
- Chenodiol
- Chloral Hydrate
- Chlorambucil
- Chloramphenicol
- Chlorcyclizine
- Chlordiazepoxide
- Chlorhexidine
- Chloroquine
- Chlorothiazide
- Chlorotrianisene
- Chlorpheniramine
- Chlorpromazine
- Chlorpropamide
- Chlorprothixene
- Chlortetracycline
- Chlorthalidone
- Chlorzoxazone
- Cholecalciferol
- Cholestyramine
- Ciclopirox
- Cidofovir
- Ciguatoxin
- Cilostazol
- Cimetidine
- Cinnarizine
- Cinoxacin
- Ciprofloxacin
- Cisapride
- Cisplatin
- Citalopram
- Clarithromycin
- Clavulanate Potassium
- Clemastine
- Clidinium
- Clindamycin
- Clofazimine
- Clofibrate
- Clomiphene
- Clomipramine
- Clomocycline
- Clonazepam
- Clonidine
- Clorazepate
- Clotrimazole
- Cloxacillin
- Clozapine
- Cocaine
- Codeine
- Colchicine
- Colesevelam
- Colestipol
- Colistimethate
- Corticotropin/Cosyntropin
- Cortisone
- Coumarin Derivatives
- Cromolyn Sodium
- Cyclacillin
- Cyclamate
- Cyclandelate
- Cyclazocine
- Cyclizine
- Cyclobenzaprine
- Cyclopenthiazide
- Cyclophosphamide
- Cycloserine
- Cyclosporine
- Cyclothiazide
- Cycrimine
- Cyproheptadine
- Cytarabine
