MANILA -- The Department of Health (DOH) warned Friday that a home remedy being pushed by the Cebu provincial government against COVID-19 might end up spreading the new coronavirus.

"Tuob," a type of steam inhalation using hot water infused with herbal properties, can "aerosolize" the virus and "may lead to further transmission of the disease," said Health Undersecretary Maria Rosario Vergeire.

• DOH: 'Tuob' does not cure, prevent COVID-19

A Cebu provincial memo earlier "enjoined" employees to practice steam inhalation twice daily at their work areas as part of a wellness program against COVID-19.

"Buti kung nangyayari lang sa bahay-bahay. Ang sinasabi natin, [No problem is we're just practicing it at home. What we're saying is] let's be careful kasi [because] we are also having other people affected with what we do," Vergeire said in an online press briefing.

Vergeire said the public should be responsible to make sure "we are not going to be the cause of further transmission" of the virus.

• 'Tuob' does not cure, prevent COVID-19: expert

A joint statement by several medical societies warned that steam inhalation could be "precarious, if done by infected individuals, as it may facilitate spread if done communally."

"Because steam inhalation does not kill the virus and may cause potential harm, we cannot, in good conscience, endorse its use as preventive or curative measure," they said.

Cebu Gov. Gwen Garcia earlier came under fire for publicly shaming doctors, who had criticized her steam inhalation remedy as cases continued to rise, particularly in Cebu City, which is administered independently.

As of Thursday, the city had 4,289 cases, 3,808 of which were considered "active." The province had 950 cases, of which 888 were active. Both areas have a combined death toll of 104, mostly in Cebu City.

The national government has deployed more than a hundred members of the elite police Special Action Force to enforce the coronavirus lockdown in Cebu City, whose residents and officials had been blamed for their supposed "complacency."

Vergeire said the DOH was looking into how the city practiced minimum health standards, such as physical distancing, after shifting to a more relaxed general community quarantine.

Health authorities are also checking if the surge in infections was driven by "imported cases" or local community transmission, she said, citing also certain mass gatherings that might have spread the virus.