Hedge woundwort is an erect perennial plant with slender underground runners and grows to a height of about 30 to 100 cm (12 to 39 in). The stem branches occasionally and is squarish and hairy, with glandular hairs on the upper part of the plant. The nodes are widely spaced and the mid-green, stalked leaves are in opposite pairs. The leaf blades are hairy, have a cordate base and are ovate with a blunt tip and with regular large teeth on the margin. The inflorescence forms a dense terminal spike and is composed of dense whorls of purple flowers with white markings. The calyx has five lobes and the corolla forms a two-lipped flower about 12 to 18 mm (0.47 to 0.71 in) long with a fused tube. The upper lip of each flower is convex with dense, glandular hairs and the lower lip is three-lobed, the central lobe being the largest. There are four stamens, two long and two short, the gynoecium has two fused carpels and the fruit is a four-chambered schizocarp. The plant has a slightly unpleasant smell.