Drugs and chemicals are one of the most common causes of non-megaloblastic macrocytic anemia. Occasionally, certain drugs can also cause megaloblastic anemias, by affecting either B12 or folate metabolism. Table 3 shows a partial list of drugs and chemicals that cause both types of anemia.
Table 3. Drugs and Chemicals that Cause Macrocytic Anemia.| Drugs Causing Non-Megaloblastic Macrocytic Anemia | Drugs Causing Folate Related Changes | Drugs Causing B12 Related Changes |
| Methotrexate | Oral contraceptives | Proton pump inhibitors (e.g., Omeprazole) |
| Acyclovir | Methotrexate | H2 blockers (e.g., Ranitidine) |
| Zidovudine (Retrovir) | Phenytoin (Dilantin) | Metformin (Glucophage) |
| Hydroxyurea | Sulfamethoxazole | Colchecine |
| Cyclophosphamide | Trimethoprim | Nitrous oxide |
| Busulfan | Zidovudine |
|
