They operate, more or less, on the same concept aromatherapy relies upon. However, instead of releasing enjoyable scents that reduce tension, mosquito coils release odors that repel mosquitoes. ... Mosquitoes are repelled by these ingredients when the materials are burned.

What does mosquito coil do to mosquitoes?

Mosquito coils work in one of two ways. Those that contain insecticides will kill (or at least “knock down”) mosquitoes, while those that contain aromatic substances (such as citronella) will repel mosquitoes or reduce the likelihood they'll bite.

Is mosquito coil really effective?

Mosquito coils are effective at deterring mosquitoes and reducing mosquito bites. However, just because they're effective doesn't mean that they're safe. Since the coils produce smoke, you should only use them outdoors or in spaces with great ventilation to prevent smoke inhalation.