My grandmother said it's okay to rub honey on my cousin's 6 month old baby who is teething. But I thought honey should be ingested by babies under the age of one. Any thoughts on this?

No. It's not ok. This is because honey may contain spores of bacteria that can cause botulism. These bacteria are harmless to adults and children over 1. But it can make babies, whose digestive and immune systems are less developed, seriously (and possibly fatally) sick. http://www.parents.com/advice/babies/feeding/when-can-my-baby-eat-honey/