How long does it usually take for abdominal muscle strain to heal?

Depends: It will depend on the cause of the strain, the degree of the strain and how you treat it following the strain. What medications you are on may have an effect as well as your general state of health. Usually a strain to an abdominal wall will be healed in 1-3 weeks. Do you have an abdominal wall hernia or oher hernia? This could be a cause of continued pain.

Weeks: The usual time line is 3 to 6 weeks for healing of an abdominal strain. Much longer than that and you may need to be examined for something that could appear to be an abdominal strain but is really something else.