Not All Teas are Created Equal
I can say with pretty full confidence that tea is a voice's best friend. It's soothing, it's healing, it's rejuvenating. It's comforting both on a physical and emotional level. As a singer, I don't think I could live without it.
There's only one problem I see with tea: there's just SO much of it. There are so many different variations, and lumping them all together in one category can be dangerous from a voice perspective. So I want to take a minute to shed some light on some of the different types of teas you might find out in the world, and how they can help (or hinder) you from a voice perspective.
When people who don't know tea talk about tea, they're usually talking about black tea. Think Lipton, Earl Grey, English Breakfast. It's dark in color (hence its name), has a robust flavor, and has high levels of caffeine, about half of that of a cup of coffee.
As a vocalist: STAY AWAY! Caffeine is dehydrating, and that can hurt your voice long term. It can also cause your vocal cords to swell. There are other ways to get energy that don't involve caffeine. So my advice: don't do black tea.
Green teas are lighter in color and milder in taste, but if you steep it for too long it gets more bitter in taste. It has a small amount of caffeine, about half that of black tea.
As a vocalist: proceed with caution. Personally, I stay away from these too when I can, purely because of the caffeine - but it's still a better choice than black. Green teas have good body soothing properties, which can be helpful as a full body recovery. But I would advise doing green tea AFTER a performance/rehearsal as opposed to before - the dangers of caffeine are worse when you sing on it.
Herbal teas can be any blend of herbs and spices. Generally, they don't have caffeine, and depending on the ingredients, they can have different medicinal properties. For example: peppermint or ginger are great for nausea, chamomile or lavender are great for relaxation, hibiscus and echinacea have good immunity building properties.
As a vocalist: have at it! Herbal teas are great, there's something to fit every need. You can get natural sources of energy without ruining your voice. And there are even some herbal teas that have throat healing properties that are excellent for the voice. My personal favorites: Throat Coat, which uses the natural healing power of slippery elm. I lost my voice before a recital once and Throat Coat helped me get it back in time to sing. I also love Take a Sec Tea, which is part of my Essential Vocal Health Bundle. It's a mix of lavender and chamomile, which is soothing for the body and the voice. I find it to be the perfect recovery from a long performance.
Other Notable Mentions
Rooibos Tea, also known as red tea. Caffeine free, technically an herbal tea, but more robust in flavor like a black tea. Highly recommend.
White Tea. Trace amounts of caffeine, so it's generally safe for the singer. It's got great immunity building properties, so definitely a great choice on a day off.
Purple Tea. Similar to white tea, it is low in caffeine and high in antioxidants. It's only been on the market for a few years, and they have a mellow flavor.
There are many more teas than what I've mentioned, but this should serve as a quick guide for the vocalist. When in doubt, check caffeine levels. And then focus on whether you need something to energize you or calm you down. Add in additional health benefits and your tea can accomplish more than you can imagine - both with your voice and your body as a whole!