Four small heaps of loose-leaf tea on a pale linen cloth, dark twisted black leaves, flat green leaves, rolled oolong balls and silvery white buds, beside an open tin and a glass cup of amber tea

Does Loose-Leaf Tea Go Bad? How to Store It and How Long It Keeps

September 15, 2026

A tin of good tea gets bought with intentions, opened once a month, and then sits through a year at the back of a cupboard until somebody wonders whether it is still worth the kettle. The answer depends on which tea it is and how the tin was kept. The loose-leaf versus tea bags guide covers why the leaf is worth the trouble in the first place, and the From Leaf to Tin guide to how tea is made explains the processing behind the differences below.

Does loose-leaf tea go bad?

What storage research measures in dry tea is gradual change: the compounds that give the cup its character shift on the shelf. A study of eight commercial green teas, sold as tea bags and stored at 20°C, found a progressive decrease in total catechins over six months. A 2024 study of seven green teas stored at room temperature found the quality of every one declining as the leaves aged. A separate 2024 study of Congou black tea that had been given an aroma-enhancing heat treatment found soluble sugars and amino acids falling during room-temperature storage while organic acids rose, and the infusion grew more acidic.

Damp is a different matter. Throw out tea that has gotten damp, smells musty or shows mold.

What the storage studies found

Study	Tea	Storage	What changed
Friedman and colleagues, 2009	Eight commercial green teas sold as tea bags	20°C for six months	Total catechins fell progressively
Zhou and colleagues, 2024	Seven green teas processed in different ways	Room temperature	Quality fell in all seven; leaf-rolled teas deteriorated less than straight, unrolled ones
Xie and colleagues, 2024	Congou black tea given an aroma-enhancing heat treatment	Room temperature	Soluble sugars and amino acids fell, organic acids rose, the infusion grew more acidic

Read together, the three studies point the same way: the teas they measured changed in storage, and green tea measurably changed within six months at 20°C. The Zhou study adds one detail: the leaf-rolled green teas showed less deterioration in storage than the straight, unrolled ones. None of the three compared green tea with black, so they do not say which keeps longer. The practical rule is to buy green tea in amounts that will be finished in a few months and to treat every tin as something to drink rather than to keep. The black tea buying guide covers grades and cut sizes.

How to store loose-leaf tea

The UK Tea and Infusions Association's storage advice fits in one sentence: keep tea in a cool, dry place and away from strongly flavored or perfumed foods. Following it means keeping tea away from the coffee, the spice drawer and anything perfumed, and keeping scented teas in their own tins.

Do	Do not
Keep it in a tin with a tight lid	Leave the lid loose
Keep the tin in a cool cupboard on an interior wall	Keep it above or beside the stove, or on a warm windowsill
Buy in amounts that will be finished in a few months, especially green tea	Buy far more green tea than will be drunk in a season
Use a dry spoon every time	Scoop with a spoon that has been near the sink
Keep flavored teas in their own tins	Store a jasmine or an Earl Grey in the same caddy as an unflavored tea

A tin with a tight lid in a cool cupboard meets all of that advice, and it costs nothing. The pantry storage guide covers the rest of the shelf, and the spice shelf-life guide applies the same cool, dry, sealed logic to the jars beside the tea.

Should tea go in the refrigerator or freezer?

No. The Tea and Infusions Association does not address the refrigerator directly, but its advice is a cool, dry place away from strong smells, and a refrigerator is neither dry nor odor-free. A cold tin brought into a warm kitchen can also gather condensation, and damp is what ruins dry leaf. Keep the tin in the cupboard.

How much caffeine is in a cup?

Beverage, 8 ounces	Typical caffeine	Note
Brewed coffee	About 95 mg	For comparison
Black tea	About 47 mg	Roughly half a cup of coffee
Green tea	About 28 mg	Brewed cup
Decaffeinated tea	About 2 mg	Decaffeination removes most, not all, of the caffeine

Those are Harvard's typical figures, and they hide the more useful fact. A 2016 analysis of commercial teas found caffeine similar across types: brewed identically (1 gram in 80°C water for three minutes), white, green, oolong and black gave roughly 16 to 19 milligrams of caffeine per gram of tea. The same study found that a three-minute steep does not extract all the caffeine, and that for the green tea it tested, full extraction took about twenty minutes. That suggests brewing accounts for much of the difference between cups. In the Tea and Infusions Association's guidance, green tea gets cooler water, around 80°C against 90 to 98°C for black.

For most adults, the FDA cites 400 milligrams a day as an amount not generally associated with negative effects, which is a great deal of tea. The FDA also notes that decaffeinated teas still contain some caffeine.

Is tea good for you?

The National Center for Complementary and Integrative Health, reviewing green tea, reports no safety concerns for green tea consumed as a beverage by adults. It reports inconsistent evidence on cancer prevention, a lower risk of coronary heart disease seen in Asian populations but not Western ones, a possible modest effect on body weight from green tea and its extracts, and, in studies that included extract supplements, a small reduction in total and LDL cholesterol. The liver problems that do appear in the literature come mostly from concentrated extracts in tablet or capsule form, not from cups. The European Food Safety Authority's 2018 review found generally no indication of liver damage from green tea infusions even at high consumption, while 800 milligrams a day of EGCG from supplements may be associated with early signs of liver damage. The NCCIH adds that green tea at high doses can lower blood levels of the beta-blocker nadolol, and that caffeine in pregnancy should stay at moderate levels. The takeaway is unglamorous: drink the tea, skip the capsules.

Does tea block iron?

Tea polyphenols reduce how much non-heme iron is absorbed. In a controlled study, black tea taken with a bread meal cut iron absorption from that meal by 79 to 94 percent, and adding milk made little or no difference.

What water, how hot, and how much?

Use fresh water and heat it once; water boiled more than once loses oxygen and makes a flat cup. The Tea and Infusions Association's measure is one rounded teaspoon of loose tea per cup, with the water at the temperatures given above. The Denver altitude cooking guide covers what altitude does to the kettle, and the black tea recipe guide walks through the whole pot.

Short answers to the rest

How can you tell if tea has faded? Open the tin and smell it. If there is little there, there will be little in the cup. Are green tea and black tea from the same plant? Yes. Green, black and oolong teas all come from Camellia sinensis, prepared in different ways. Green tea leaves are steamed or pan-fired and dried without being fermented, while black tea is made by encouraging the leaf to oxidize. The Mariage Frères tea guide covers how that house's teas differ in style and how to choose among them.

Visitors can ask staff questions in the shop at 263 Josephine Street in Cherry Creek, Denver, and products ship nationwide from theambrosianpantry.com.