Not many. When Methotrexate is used to treat ectopic pregnancy, usually only one dose needs to be given. Therefore, most women will do well without any side effects. If they do have side effects, it will be mild and temporary. They include nausea, abdominal pain, sores in the mouth, dizziness, etc.
Not much. Because it is used for such a brief period of time in this situation, side effects are relatively rare.
Mucositis. (mouth throat sores) nausea, vomiting diarrhea.