They may also be struck by dizziness, vomiting and diarrhea, pharmacists warn.

The public should not stock up on the flu medications as the government has enough to combat a pandemic, said Iris Chang of the Practising Pharmacists Association of Hong Kong.

Her warning came as queues formed outside pharmacies yesterday as residents, spurred by memories of the deadly SARS virus in 2003, stocked up on medical supplies to counter any potential outbreak.

While there have been no reported cases of the swine flu strain in Hong Kong, housewives and domestic helpers were taking no chances and joined the scramble for masks and anti-flu drugs.

The antiviral medicines are not available over the counter.

"There are serious side effects to taking these drugs that one might not be aware of, " Chang said.

She pointed out that taking Tamiflu unnecessarily might increase resistance to the drug.

If Tamiflu becomes ineffective against the latest strain of flu, powder- form Relenza will also be ineffective since both target the same types of virus, she said.

Meanwhile, pharmacies have united to offer free advice in an attempt to ease public fears.

About 400 pharmacies, or 95 percent of the market, have joined a campaign to advise those seeking quick reassurance that all they are suffering from is the common cold.

Pharmacies will display a sign notifying customers of the service.

The pharmacists' association launched the exercise as an extra measure to encourage calm, educate the public on the differences between a cold and the flu, and to advise on remedies and follow up action.

"The pharmacies will advise individuals whether the symptoms they have reflect a cold or something more serious such as flu," head of Pharmacovigilance Kevin Cheung Kin-man said.

"If the symptoms persist for days, people will be advised to consult a doctor," Cheung said. "In the meantime, in the case of colds, pharmacists will be able to recommend appropriate over-the- counter medication."