Realgar, α-As4S4, is an arsenic sulfide mineral, also known as “ruby sulphur” or “ruby of arsenic”. It is a soft, sectile mineral occurring in monoclinic crystals, or in granular, compact, or powdery form, often in association with the related mineral, orpiment (As2S3).
In Traditional Chinese Medicine (TCM), realgar is often used in combination with herbs. An investigation found a total of 191 different, realgar-containing traditional Chinese patent medicines, and about 87% of them were for oral application. Realgar is said to:
counteract toxic pathogen both externally and internally. For abscess swelling and sores, it can be used singly or in compound prescription for external application mostly. When taken internally, it is combined with blood-activating and abscess-curing herbs to obtain the action of activating blood to relieve swelling, removing toxicity to cure sores. For example, it is combined with Ru Xiang, Mo Yao and She Xiang in Xing Xiao Wan from Wai Ke Quan Sheng Ji. For itching of skin due to scabies and ringworm, it is often combined with dampness-astringing and itching-relieving herbs to obtain actions of killing parasites and curing ringworm, astringing dampness and relieving itching. For instance, it is combined with the same dose of Bai Fan in powder mixed with clear tea for external application in Er Wei Ba Du San from Yi Zong Jin Jian. For poisonous insect bite, it is mixed with sesame oil and then applied on the afflicted sites.
This herb can kill parasites so it is indicated for intestine track parasites. For roundworm induced abdominal pain, it is often combined with other roundworm-killing herbs to reinforce action. For instance, it is combined with Qian Niu Zi and Bing Lang, etc. in Qian Niu Wan from Shen Shi Zun Sheng Shu. For anus pruritus caused by pinworm, it can be made into gauze strip by mixing with vaseline, and then inserted into the anus.
In addition, according to some ancient formulas, this herb can dispel phlegm and check malaria for internal application, so it can also be indicated for epilepsy, asthma and malaria.
Longtime topical over-dose or oral intake of realgar can cause chronic arsenic poisoning and even death. Chinese authors recently published the case of a 35-year-old Chinese man, who was diagnosed with severe psoriasis and died of fatal acute arsenic poisoning after he applied a local folk prescription ointment containing mainly realgar to the affected skin for about 4 days. The autopsy showed multiple punctate haemorrhages over the limbs, pleural effusion, oedematous lungs with consolidation, mild myocardial hypertrophy and normal-looking kidneys. The histopathological examination of renal tissue showed severe degeneration, necrosis and desquamation of renal tubular epithelial cells, presence of protein cast and a widened oedematous interstitium with interstitial fibrosis. The presence of arsenic in large amount in the ointment (about 6%), in blood (1.76 μg/mL), and in skin (4.71 μg/g), were confirmed analytically. The authors also review 7 similar cases in literature.
My advice is that, when you see recommendations by TCM practitioners like this one
the typical internal dose of realgar is between 0.2 and 0.4 grams, decocted in water and taken up to two times per day. Some practitioners may recommend slightly higher doses (0.3-0.9 grams). Larger doses of realgar may be used if it is being applied topically
you think again and consider that TCM really is not a form of healthcare that can be trusted to be safe.