There are a few ATMs available on Langkawi; however, like ATMs on any popular island, they can run out of cash. The most reliable ATMs are found in the airport and Pantai Cenang. Stock up on Malaysian ringgit before leaving the mainland or use the ATM at the airport upon arrival. If the ATM network isn't working, you can exchange currency in many shops. You should also know how to exchange money and learn the current exchange rates for Malaysia.
The cheapest duty-free shopping can be found in Kuah rather than at tourist beaches. Even with no tax, Langkawi is still a tourist island—many items for purchase can be found cheaper in Kuala Lumpur. Visitors must stay a minimum of 48 hours on Langkawi to legally avoid paying tax on purchased goods.
Because Langkawi enjoys a duty-free status, alcohol is significantly cheaper on the island. Airport prices are the worst, so it's best to wait to purchase spirits from smaller shops. Even with discounted drinks, Langkawi isn't really rowdy—consider going to the Perhentian Islands if you want to party. If flying from Langkawi to Singapore, remember that you'll have to pay a steep duty on any alcohol or tobacco taken into Singapore.
Water and Electricity
As with the rest of Malaysia, you should stick to drinking bottled water while visiting Langkawi. As for electricity, 240 volts / 50 Hz with the square-pronged, British-standard power outlets (BS-1363). The electricity on Langkawi is mostly stable; however, power sags and surges do sometimes occur when work is being done.
Lots of green space and mangrove forests cause mosquitoes to be a real nuisance on Langkawi. Dengue fever is also a risk from daytime bites. Try to take precautions to avoid mosquito bites.