Medical experts are calling for a broader public understanding of psoriasis, a chronic skin disorder, warning sufferers not to blindly seek treatment that may lead to health risks.

The warning comes after a recent incident of medication misuse in Shanghai.

A 26-year-old woman who is a psoriasis patient was diagnosed with serious silver poisoning after taking a remedy called colloidal silver she bought from an overseas website.

Colloidal silver is a suspension of tiny metallic silver particles in a colloidal base. It has been used to kill bacteria and viruses.

But long-term use of colloidal silver can lead to argyria, a condition in which silver salts accumulate in the skin, eyes and internal organs with the skin becoming blue-gray, experts say.

The young woman developed an ashen face, a typical symptom of argyria. Doctors found 25 times more silver in her body than healthy people.

So far, doctors are carrying out treatment on the woman.

Psoriasis is an immune-mediated disease that affects the skin. It is characterized by red skin with flaky, silver-white patches on the elbows, knees, trunk and other parts of the body. Psoriasis is not contagious, but typically a lifelong condition.

"Although there's no cure, various treatments can help control its symptoms," says Zheng Jie, dermatology expert from Shanghai Ruijin Hospital, who has worked in this field for decades.

For psoriasis sufferers, the first step is a good daily skin cleaning and then maintenance work. With both externally applied medicine and regular ultraviolet-light therapy, the symptoms will be significantly controlled, Zheng says.

Manufacturers of colloidal-silver products often claim that such silver-containing products can cure ailments, boost immune system, fight bacteria and viruses, and treat cancer, HIV/AIDS, shingles, eye ailments and prostatitis.

But there are no scientific studies on such health claims in reputable peer-reviewed medical journals.

Recently, these silver-containing products have become easily accessible for Chinese consumers, especially online. At the country's popular online shopping platform Taobao.com, imported colloidal-silver products are sold under the category of health supplements with prices ranging from 100 yuan ($16) to 600 yuan.

"Colloidal silver isn't considered safe or effective for any of the health claims manufacturers make," says Brent Bauer, an internist at the US Mayo Clinic.

"Silver has no known purpose in the body. Nor is it an essential mineral, as some sellers of silver products claim," he writes in an article about the safety and effectiveness of colloidal silver on the clinic's website.

Zheng notes that patients are often desperate to try anything and everything. "The so-called cure on the market is a fraud," he says.

"Doctors, health authorities and media should provide more guidance for the public," he says. "Government should strengthen the supervision of imported health tonics and supplements sold online to guarantee the products' safety."

Contact the writer at wanghongyi@chinadaily.com.cn.