| Diphenhydramine (Benadryl) | First-generation (nonselective) antihistamine/antiemetic | B | Yes | Possible oxytocin-like effects at high doses |
| Brompheniramine | First-generation (nonselective) antihistamine | C | Not known | Limited data |
| Chlorpheniramine | First-generation (nonselective) antihistamine | C | Not known | Drug of choice |
| Pheniramine | Ophthalmic antihistamine/decongestant (pheniramine 0.3%/naphazoline 0.025%) | C | Not known | Limited data; likely low risk with limited use |
| Cetirizine (Zyrtec) | Second-generation (selective, nonsedating) antihistamine | B | Not known | Acceptable alternative to first-generation agents |
| Loratadine (Claritin) | Second-generation (selective, nonsedating) antihistamine | B | Not known | Acceptable alternative to first-generation agents |
| Fexofenadine (Allegra) | Second-generation (selective, nonsedating) antihistamine | C | Not known | No human data, animal data suggest some risk |
| Phenylephrine | Sympathomimetic decongestant | C | Yes† | Safety not established, should be avoided in first trimester |
| Pseudoephedrine | Sympathomimetic decongestant | C | Not known | Behind-the-counter purchase; possible association with gastroschisis, small intestinal atresia, and hemifacial microsomia; should be avoided in first trimester |
| Guaifenesin | Expectorant | C | Not known | Safety not established, should be avoided in first trimester |
| Dextromethorphan | Nonnarcotic antitussive | C | Not known | Appears to be safe in pregnancy |
