Black haw is a shrub with a long history in folk herbalism. Its bark contains relatives of salicin, the compound known from white willow, but modern clinical data is thin. Most modern use is based on that traditional record rather than rigorous trials.
People commonly reach for black haw during menstrual cramping or muscle tightness. Some also use it as a gentle calming herb, though formal research behind these applications is sparse.
You will find black haw sold as dried bark, liquid extracts, and glycerites. Dosing shifts with the form and strength, so follow the label on whatever product you pick.
A firm safety rule: avoid black haw during pregnancy. It may influence uterine activity. If you are nursing or managing a health condition, check with your doctor before taking it.