Mosquito patches and repellents have been flying off the shelves, but retailers have assured the public that they are taking steps to ensure stocks remain available.
Supermarkets and pharmacies that The Straits Times contacted reported a surge in demand islandwide, since news of the first locally transmitted case of the Zika virus broke last Saturday.
Demand has been particularly strong in outlets in Aljunied Crescent and Sims Drive, where 77 people have been detected with Zika.
NTUC FairPrice said the sale of mosquito repellents, patches and insecticide across its branches has doubled. "We carry three types of house-brand insecticides, which have also seen a spike in sales this past week," said its senior director for purchasing and merchandising, Mrs Mui-Kok Kah Wei.
A check on the supermarket website yesterday evening showed that the Baygon Multi Insect Killer was temporarily out of stock. The spray product, which costs $6.20, promises "maximum killing power" against mosquitoes, cockroaches and flies.
By the end of yesterday, several pictures of empty shelves across the island were circulating on the Internet, though stores maintain that they have sufficient supply.
Stock replenishments are under way at four Watsons outlets in the Aljunied Crescent and Sims Drive clusters, said general manager Dominic Wong.
Supermarket chain Sheng Siong saw between 25 per cent and 30 per cent growth in sales of anti-mosquito patches, coils, sprays and clip-on repellents, with a "substantial" increase in outlets in the north and east.
A spokesman said: "For mosquito patches, it is the ease and convenience in usage... As for mosquito coils, affordability and efficiency are reasons for their demand."
Sheng Siong will be stocking up around two to three months' worth of supplies to ensure stock availability during this period.
Mosquito patches were the most popular insect repellent item at Cold Storage, Giant and Guardian outlets here, said a spokesman.
A Guardian pharmacy spokesman reported a twofold increase in sales of these items as compared with last week, while sales at its five stores in the affected Aljunied area have soared four times.
"Emergency deliveries to key stores have been arranged to ensure that we can replenish the stocks as fast as possible," the spokesman added.
Ms Mary Gan, deputy director of merchandising at Unity Pharmacy, said sales of mosquito repellent items, such as sprays, patches, bracelets, lotions, wipes and clip-ons, have tripled at its 59 outlets here. She added that the pharmacy is "well stocked".