Major = Do not use combination; contraindicated; strongly discourage patients from using this combination; a serious adverse outcome could occur.

Moderate = Use cautiously or avoid combination; warn patients that a significant interaction or adverse outcome could occur.

Minor = Be aware that there is a chance of an interaction; advise patients to watch for warning signs of a potential interaction.

Likelihood of Occurrence
Likely = Well-controlled human studies have demonstrated existence of this interaction.

Probable = Interaction has not been documented in well-controlled studies, however interaction has been demonstrated in human studies or in controlled animal studies plus multiple case reports.

Possible = Interaction has been documented in animal or in vitro research, or interaction has been documented in humans but is limited to case reports or conflicting clinical research.

Unlikely = Interaction has been demonstrated in animal or in vitro research but has been shown not to occur in humans.

Severity
High = Life threatening or requires medical intervention to prevent a serious adverse event.

Moderate = Worsened clinical status and/or requires medication adjustment.

Mild = May cause minor clinical side effects. Unlikely to require medication adjustment.

Insignificant = Drug or supplement levels may be affected but will not cause clinical effects.