European shares briefly turned positive on Tuesday, with drugmakers amongst the best performers, as investors shifted money in the defensive sectors after Standard & Poor's warned it may downgrade 15 euro zone countries.

The STOXX Europe 600 Health Care index <.SXDP> was up 0.2 percent, while the STOXX Europe 600 Banks index <.SX7P> fell 0.4 percent.

(Reporting by Joanne Frearson)