| Clivers herb | | Herbal remedies | 1 |
| Clobutinol hydrochloride | 14860-49-2 | Antitussives | 1 |
| Clofibrate | 637-07-0 | Fibrates | 1 |
| Clopamide | 636-54-4 | Diuretics | 1 |
| Clopidogrel bisulfate (Form-2) | 135046-48-9 | | 1 |
| Clorsulon | 60200-06-8 | | 1 |
| Closantel Sodium | 61438-64-0 | | 1 |
| Clostebol | 1093-58-9 | Androgens | 1 |
| Clove tree | | Herbal remedies | 1 |
| Cloxazolam | 24166-13-0 | Anxiolytics | 1 |
| Clubmoss herb | | Herbal remedies | 1 |
| Coal tar | | Coal tar preparations | 1 |
| Cocamidopropyl betaine | 61789-40-0 | Dermatological Agents | 1 |
| Cocarboxylase Chloride | 67-52-7 | | 1 |
| Cocoa peels | | Herbal remedies | 1 |
| Colesevelam Hydrochloride | 182815-44-7 | | 1 |
| Colesevelam-Hydrochloride | 182815-44-7 | Bile acid sequestrants | 1 |
| Colestipol Hydrochloride | 37296-80-3 | | 1 |
| Colistin Sulfate | 1264-72-8 | Antibacterials | 1 |
| Collagenase clostridium histolyticum | 9001-12-1 | Enzyme Replacements/modifiers | 1 |
| Collodion 4% | 9004-70-0 | Dermatics | 1 |
| Colloidal Silver Solution | 9007-35-6 | Antimicrobial agents | 1 |
| Colloidal silica | 7631-86-9 | Disinfectants | 1 |
| Coltsfoot leaf | | Herbal remedies | 1 |
| Coluracetam | 1393477-72-9 | | 1 |
| Comfrey | | Herbal remedies | 1 |
| Common mallow flower | | Herbal remedies | 1 |
| Common thyme herb | | Herbal remedies | 1 |
| Condurango cortex | | Herbal remedies | 1 |
| Coneflower tincture | | Herbal remedies | 1 |
| Conestat alfa | 80295-38-1 | Hemostatics | 1 |
| Conjugated Estrogen | 12126-59-9 | | 1 |
| Copper (II) carbonate basic | 12069-69-1 | Minerals and electrolytes | 1 |
| Copper (II) oxide | 1317-38-0 | Minerals and electrolytes | 1 |
| Copper gluconate | 527-09-3 | | 1 |
| Copper tetraMIBI tetrafluoroborate | 103694-84-4 | | 1 |
| Copper(II) chloride dihydrate | 10125-13-0 | | 1 |
| Coriander | | Herbal remedies | 1 |
| Couch grass | | Herbal remedies | 1 |
| Cowslip flower | | Herbal remedies | 1 |