An R isomer can be either dextrorotatory or levorotatory, depending on its exact substituents.
From the en.wikipedia.org
The levorotatory form, called levomethamphetamine, is an over-the-counter drug used in inhalers for nasal decongestion.
From the en.wikipedia.org
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Levorotary: rotating to the left
Dextrorotation and levorotation (also spelled laevorotation)The first word component ' comes from Latin word for dexter "right (as opposed to left)". Laevo or levo comes from the Latin for laevus, "left side. ...
That rotates the plane of polarized light to the left, or anticlockwise
LEV-oh-ROTE-tuh-tore-ee/ Rotating a plane of polarized light counterclockwise (said of a chemical compound). Compare: dextrorotatory