To use cold tea bags as a compress, soak a tea bag in clean water and then place in the refrigerator for 30 minutes. Then, place the tea bags on your eyes. Leave for 10 minutes or so twice daily before removing and rinsing the area with warm water. Source.
September to October is the rainy season in Langkawi and this is the period which most tourists like to avoid. But the fact is even during the rainy season, it rains only for about 2 hours a day but usually in the late afternoon and at night.
Conversely there is no guarantee that during the dry season the weather will be dry. Just last week we had three days in a row of overcast weather and daily rain in central Bali. March can be great, April a bit better. Far fewer tourists are here during March and April and one can bargain great deals at hotels.