A woman died after drinking a poisonous herbal tea bought at a San Francisco Chinatown shop.

Yu-Ping Xie, 56, died at California Pacific Medical Center's Pacific campus on Saturday after being hospitalized for almost two weeks, according to the San Francisco Department of Public Health.

In a separate incident, another city resident, a man in his 30s, was hospitalized after drinking a different blend of herbal tea bought from the same herbalist, Sun Wing Wo Trading Co at 1105 Grant Avenue in Chinatown.

He was discharged from the hospital on March 12 after doctors determined he had recovered.

The public health authority said the two people became critically ill within an hour of drinking tea made from leaves supplied by the herbalist. Each quickly developed weakness, and then life-threatening abnormal heart rhythms, requiring resuscitation and intensive hospital care.

A plant-based toxin, aconite was found in lab tests of the patients and the tea samples they provided, according to the health department, which has removed the products containing aconite from the shelves.

The shop remains open for business but declined to talk about the incidents.

Aconite, commonly called monkshood, wolf's bane or fuzi in Chinese, is used in Asian herbal medicine to treat pain, bruises and other conditions. Raw aconite roots are generally toxic, and are used only after adequate processing. There is no antidote for aconite poisoning.

Once it is consumed, symptoms occur within a few minutes or up to a couple hours, depending on the amount ingested.

These include numbness or tingling of the face, mouth or limbs; weakness in the limbs; paralysis; low blood pressure; irregular heartbeat; chest pain; slow or fast heartbeat; nausea; vomiting; and abdominal pain and diarrhea, according to the public health department.

The department urges people who have purchased tea from the shop to throw it away immediately.

According to Liu Yuankai, president of the Chinese Herb Trade Association of Northern California (CHTANC), the tea prescriptions for the two victims didn't contain aconite.

Liu told local Chinese media that he has been assisting in the investigation.

The authorities haven't determined the source of the poison. Liu said chances were that shop assistants mistook the ingredient containing aconite for other ingredients; or the herbal suppliers shipped the poisonous ingredients to the shop, or the victims took the poisonous herbal somewhere else.

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