This box of tea has an expiration date which has passed but I would like to know if I can still use it. What do you think?
Tea bags will be fine for at least a year in the pantry, but even long after that, they're still safe to consume. They just might change colour or flavour.
If your tea has an expiration date then it's just for best quality, not safety. I've personally found tea bags sitting at the back of the pantry that were more than 3 years old, the packaging had even started to fade, and the tea was still fine. I just had to steep it for a little longer.
Yes, it should be fine. I am drinking Japanese green tea right now which has been stored in a tight tin. It was expired in 2009. I heard that green tea is OK to dring after its expired when I was in Japan. However, flavour is definitely not the greatest if you know the real taste. They suggest to keep them in FREEZER if you can.
It's funny to see westerners asking "when does tea go off"? Answer --- it doesn't.
Here in Asia, many people drink tea that is years old, including the Chinese who have a tea that is more than 20 years old and is highly desired and very expensive to buy.
Tea does not 'go off'. It is dried, so like any dried herb. Like someone else said, you may have to steep it a little longer but it will never hurt you.
Stop believing all this hype about 'sell bye' dates. It's why so much food is wasted in the west. For sheer profit. Nothing more.
Similar to the comments above about "freshness" tea loses it's medicinal qualities as it ages. If you're looking to drink green tea for it's health benefits the quality matters. Green tea that is more than 6 months old has a significant decrease in the amount of beneficial antioxidants the body can absorb. Personally I'm a big fan of loose leaf but if you're going to drink any brand of bagged teas my vote is for Mighty Leaf. They're big on flavor and high in quality.
If you're looking for creative ideas on how to use old tea I've heard they make good fertilizers and also have heard of people using them as air fresheners in their sock drawers.
Generally tea, like other dry herbs, doesn't really expire, but may loose flavor and aroma. So while your tea bag may not taste great, it should still be ok to consume, if the tea bag hasn't come in touch with too much humidity. Only with excessive humidity, the dry leaves may absorb it and develop mold.
Green tea, fresh white tea
Green tea and fresh white teas may deteriorate faster. This is because it contains more water relative to other teas, and therefore the leaves will oxidate and change color. Green tea should ideally be consumed within 6 months. If you can't, I recommend to split it in several bags. Then leave one bag in the cabinet and store the rest in the freezer to preserve the flavor for up to two years.
Black tea, oolong tea
On the other hand, teas like black tea, have very little water content left, and will therefore last longer. When stored in an airtight jar, you'll probably be able to keep the taste fresh for two years.
White tea, pu erh tea
Pu erh tea (and other dark teas) as well as aged white teas doesn't really expire, but improve in flavor due to its aging ability. For pu erh, the older the better, while for aged white tea, it's supposed to be the best around 7 years of aging. This, however, will depend on the specific storage conditions.
If you're interested in all the factors which are important for storing tea, you may read my guide: how to store loose leaf tea. It's about storage for loose leaf tea, but the same principles in fact apply for tea bags as well.