Glow sticks are a popular night time product. The sticks are very safe and although they look harmful, the chemicals used are quite mild. Although it should never be ingested, the worst it could give you is an upset stomach similar to as if you had drank washing liquid. There is however a glass vial inside which cracks to allow the two chemicals to mix and begin glowing. For this reason, it is recommended to throw out a leaking glowstick.