The sudden death of a woman in Beijing who had been taking healthcare products from a direct-selling company to treat fever has raised questions about China's direct-sales industry.

Lin Li, a pseudonym, caught fever on Feb 26 and drank nothing but bottled fruit juice in an attempted detox.

She died five days later at 34 years old due to severe lung infection, Beijing Youth Daily have reported.

She had been drinking packaged fruit juice and taking capsule pills from Nu Skin, a direct-selling company, for more than a year whenever she felt sick, according to her friend and husband who both recently spoke with Beijing Youth Daily.

Lin was since 2016 employed by Nu Skin, a global company selling healthcare products and dietary supplements that entered the Chinese mainland in 2003 and obtained permits for direct sales in 2006, according to its official website.

Her husband said Lin had been persuading family members and friends to use the company's products and frequently engaged in promotional campaigns for the brand.

Her habit escalated in 2017 when she began refusing to vaccinate her child from fear of harming the child's health.

By this stage she was taking 16 pills and two packets of juice powder each morning.

The company said in an online statement Monday that it has established a team to investgate the matter.

"If our distributors are found to make misleading or exaggerating claims, the company will not avert its responsibilities," it said.

China allows direct sales under limited conditions but bans pyramid schemes, which use income generated from new members to pay off senior members.

The State Administration for Market Regulation launched a campaign in January to crack down on irregularities in the sale of healthcare products.

Many of these investigations have targeted direct-selling firms accused of deceiving consumers.

The campaign has been marked by several high-profile cases, including the death of a seven-year-old girl who used products from a direct-selling company as part of her cancer treatment.