Does dong quai work alone or only in combination?
Tested alone, results are mixed and generally unimpressive; in combination formulas -- how it's traditionally used -- studies show significantly better results for hot flashes and night sweats.
The short answer
Dong quai, called "female ginseng" in Traditional Chinese Medicine, is almost never used alone traditionally -- it typically appears in soups (like dong quai chicken soup) or classical formulas like Si Wu Tang alongside other herbs. That context matters: tested by itself, dong quai's modern trial results are weak and mixed, but studies using it within combination formulas -- paired with red clover, black cohosh, chamomile, or classical TCM blends like Er-Xian Decoction -- found significantly better results for hot flashes and night sweats. The evidence itself suggests "standalone" may simply be the wrong framing for this particular herb.