Red dead-nettle is an annual with one to several stems ascending or spreading from the base up to 10-40 cm long. The herbage is inconspicuously hairy. The small leaves are opposite on the square (cross-section) stems. They are heart-shaped with rounded teeth on the margins. The venation is prominent, with raised areas between the veins. The leaves are petiolate, and they become reduced in size upwards on the stem.
The inflorescence is a tightly spaced series of whorls of pink or lavender flowers. The inflorescence resembles a 4-sided pagoda, with the pinkish flowers partially hidden by the larger leaves above them. The calyx is 5-6 mm long. The corolla is pink-purple and from 10-15 mm long. The upper lip is hooded, while the lower lip is prominent and two-lobed.
Red dead-nettle may be found in moist, disturbed places, including yards, gardens and fields.
Red dead-nettle may be found across much of North America. It originated in Eurasia.
In the Columbia River Gorge, it may be found at approximately 100' elevation from the western entrance to the gorge east to about Starvation Creek.
All parts of red dead-nettle are edible, and may be used in salads. Plants should be washed before use, and care must be taken to collect plants which have not been exposed to herbicides or insecticides. Poultices of the fresh plant may help reduce swelling and speed the healing of stings, small wounds, and minor burns. The leaves were used as a tea to reduce both internal or external bleeding, and to relieve diarrhea.