drug reaction

Pt was scheduled in the morning for leg pain. Doc gave pt a prescription for pain. Pt came back in the afternoon due to drug reaction. Do I have to bill the 2nd visit on the same day?

re: drug reaction

Medicare: "Contractors may not pay two E/M office visits billed by a physician (or physician of the same specialty from the same group practice) for the same beneficiary on the same day unless the physician documents that the visits were for unrelated problems in the office or outpatient setting which could not be provided during the same encounter (e.g., office visit for blood pressure medication evaluation, followed five hours later by a visit for evaluation of leg pain following an accident)".
The key is "unrelated" otherwise, only one visit code to cover both encounters. An adverse reaction is an "E" code and that can only be billed as a secondary code. The first code is the manifestation, ex, hives. Many payors would consider this related to initial visit. Code the level to include both visits, in that case.