Symptoms of digitalis poisoning include nausea, vomiting, severe headache, dilated pupils, problems with eyesight, and convulsions at the worst level of toxicity.

The plant commonly forms a single, upright, more or less uniformly leafy stem that is partly ascending at the base.

[7] The leaves are moderately green in colour, woolly, veined, and covered with white hairs on the underside.

[7] The flowers are tubular and bell shaped, pale yellow to whitish with brown or violet lines (ferruginous reticulated markings),[8] and the centre lobe of the lower lip is 8 to 13 mm long.

[7] It is native to Anatolia and the Balkans, where it is found in Albania, Bulgaria, Croatia, Greece, Thrace (European Turkey), Hungary, Serbia, Kosovo and Romania,[6] eastwards to northern Moldova.

The state of Minnesota considers it a noxious weed,[5][10] and it is an invasive species of grasslands and woodlands in Wisconsin,[11] and Kansas.

[4] It has also naturalised in the US states of Connecticut, Indiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Nebraska, New Hampshire, New Jersey, New York, Ohio, Pennsylvania, Vermont and West Virginia.

[14] More than 70 bitter glycosides with cardiac activity, with five different aglyconees digitoxigenin, gitoxigenin, digoxigenin, diginatigenin and gitaloxigenin in the leaves act as a protection against herbivores.

[20] William Withering is credited as the first to clinically investigate the plant as a therapy for dropsy, writing a book in 1785 about the potential medical uses of D. purpurea extracts after his human trials.

[22] However, it is becoming less frequently used[21] due to the narrow therapeutic margin[19] and high potential for severe side effects.

[20] Digoxin is being replaced by newer drugs[21] including beta blockers, angiotensin-converting enzyme inhibitors, and the calcium channel blocking agents.

[25] The commercial production of digoxin from D. lanata involves growing the plant from seed for two years, harvesting and drying it in a silo, then the leaves are crushed into a powder, and the compound is extracted and purified using chemical processes.

[26] Digoxigenin (DIG) is a steroid found in the flowers and leaves of Digitalis species, and is extracted from D. lanata.

Once hybridisation occurs, RNA with the incorporated DIG-U can be detected with anti-DIG antibodies conjugated to alkaline phosphatase.