Tea is one of the world’s most popular beverages.
The most common varieties—green, black, and oolong—all come from the leaves of the Camellia sinensis plant. Green tea in particular has gained popularity for its antioxidant content.
Tea has been used for its healing properties for centuries, and modern research supports many of its benefits. Plant compounds in tea may help reduce the risk of chronic conditions like heart disease and diabetes.
Lose weight
Gain muscles
Eat healthy
Explore new cuisines
Maya T.
Available on the App StoreBut more isn’t always better. Exceeding 3–4 cups (710–950 ml) per day could lead to some unwanted effects.
Here are nine side effects of drinking too much tea.
1. Reduced iron absorption
Tea contains tannins, compounds that can bind to iron and make it harder for your body to absorb.
Iron deficiency is one of the most common nutrient deficiencies worldwide. If you already have low iron levels, drinking too much tea could make things worse.
A narrative review examining tannin consumption and iron bioavailability found that tannins significantly inhibit non-heme iron absorption—the type found in plant foods.1 This matters most for vegetarians and vegans who rely on plant-based iron sources.
The good news: timing matters. Research shows that waiting just one hour after a meal to drink tea reduces the inhibitory effect by about 50%.2
If you have low iron levels but still want to enjoy tea, drink it between meals rather than with food.
Summary: Tannins in tea can reduce iron absorption, especially from plant foods. Waiting an hour after meals to drink tea helps minimize this effect.
2. Increased anxiety and restlessness
Tea leaves naturally contain caffeine. Drinking too much can trigger feelings of anxiety, stress, and restlessness.
A typical cup (240 ml) of tea contains 11–61 mg of caffeine, depending on the variety and brewing time. Black teas have more caffeine than green or white varieties.
A 2024 meta-analysis found that caffeine intake significantly increases anxiety risk in healthy individuals. The effect is dose-dependent—low doses moderately increased anxiety, while doses above 400 mg had a much stronger effect.3
Most people tolerate caffeine well at moderate doses, but sensitivity varies. If tea makes you jittery or nervous, that’s a sign to cut back.
Caffeine-free herbal teas offer an alternative. Unlike true teas from the Camellia sinensis plant, herbal teas are made from flowers, herbs, and fruits without caffeine.
Summary: Caffeine from tea can increase anxiety, especially at higher doses. If you’re sensitive, try switching to herbal teas or reducing intake.
3. Poor sleep
Caffeine in tea can interfere with your sleep, even hours after drinking it.
Melatonin—the hormone that signals your brain it’s time to sleep—may be suppressed by caffeine. This can make it harder to fall asleep and reduce sleep quality.
A 2023 systematic review and meta-analysis of 24 studies found that caffeine reduced total sleep time by 45 minutes and sleep efficiency by 7%. It also delayed sleep onset by about 9 minutes and increased nighttime waking by 12 minutes.4
The review also found that caffeine reduced deep sleep duration while increasing light sleep—meaning even if you sleep, you may not feel as rested.
If you’re having trouble falling asleep and drink caffeinated tea regularly, try cutting off intake at least 6 hours before bedtime.
Summary: Caffeine from tea can reduce sleep time and quality. Avoid caffeinated tea in the hours leading up to bedtime.
4. Nausea
Drinking tea on an empty stomach can cause nausea in some people.
Tannins are responsible for tea’s bitter, dry taste. They can also irritate the digestive tract, leading to nausea or stomach discomfort.
Suggested read: Is Tea Safe During Pregnancy? Risks & Benefits Explained
Sensitivity varies widely. Some people feel queasy after just 1–2 cups (240–480 ml), while others can drink several cups without any issues.
If tea upsets your stomach, try these fixes:
- Add a splash of milk (tannins bind to proteins, reducing irritation)
- Eat something before or with your tea
- Reduce the steeping time to lower tannin content
Summary: Tannins in tea can irritate the stomach and cause nausea, especially on an empty stomach. Eating food or adding milk can help.
5. Heartburn
Caffeine in tea may trigger or worsen heartburn and acid reflux.
Caffeine relaxes the lower esophageal sphincter—the muscle that keeps stomach acid from flowing back up into the esophagus. It can also increase stomach acid production.
Not everyone experiences this. Individual responses vary, and many people drink tea without any digestive issues.
If you frequently experience heartburn after drinking tea, try reducing your intake or switching to low-caffeine varieties. White tea typically has less caffeine than black or green tea.
Summary: Caffeine can relax the esophageal sphincter and increase acid production, potentially causing heartburn in some people.
6. Pregnancy complications
High caffeine intake during pregnancy has been linked to increased risk of miscarriage and low birth weight.
A dose-response meta-analysis of 60 studies found that each additional 100 mg of caffeine per day was associated with a 14% increased risk of spontaneous abortion and 19% increased risk of stillbirth.5
The American College of Obstetricians and Gynecologists recommends keeping caffeine intake under 200 mg daily during pregnancy. Since tea contains about 20–60 mg per cup, that means limiting yourself to roughly 3 cups per day.
Caffeine-free herbal teas seem like a safe alternative, but not all are appropriate during pregnancy. Herbal teas containing black cohosh or licorice may induce premature labor and should be avoided.
Suggested read: 10 Herbal Teas with Real Health Benefits (Science-Backed)
If you’re pregnant and unsure about your tea intake, consult your healthcare provider.
Summary: Caffeine from tea may increase pregnancy risks. Stick to 200 mg or less daily, and be cautious with certain herbal teas.
7. Headaches
Caffeine has a paradoxical relationship with headaches. Occasional use may help relieve them, but regular consumption can make them more frequent.
Daily caffeine intake—even as little as 100 mg—may contribute to chronic headaches. When you become dependent on caffeine, skipping a day can trigger withdrawal headaches.
Tea contains less caffeine than coffee, but strong black teas can still deliver up to 60 mg per cup. If you drink several cups daily, that adds up.
If you experience recurring headaches, try gradually reducing your tea intake to see if symptoms improve.
Summary: Regular caffeine consumption from tea may contribute to chronic headaches, especially if intake varies day to day.
8. Dizziness
Feeling light-headed or dizzy after drinking tea is uncommon but possible, especially with high caffeine intake.
This typically happens with doses above 400–500 mg of caffeine—roughly 6–12 cups of tea consumed in a short period. However, sensitive individuals may experience dizziness at lower amounts.
If you frequently feel dizzy after drinking tea, try switching to lower-caffeine options like white tea or herbal varieties.
Summary: Dizziness from tea is rare and usually only occurs with very high intake. Sensitive individuals should opt for lower-caffeine teas.
9. Caffeine dependence
Caffeine is habit-forming. Regular consumption from tea or any source can lead to physical dependence.
Withdrawal symptoms typically include headaches, irritability, fatigue, and difficulty concentrating. These can start within 12–24 hours of your last dose and may last several days.
Research suggests dependence can develop after just 3 consecutive days of caffeine intake. The more you consume and the longer you’ve been drinking it, the more pronounced withdrawal symptoms tend to be.
If you want to reduce your tea intake, taper gradually rather than quitting cold turkey to minimize withdrawal effects.
Suggested read: What is caffeine, and is it good or bad for health?
Summary: Regular tea consumption can lead to caffeine dependence. Withdrawal symptoms include headaches, fatigue, and irritability.
The bottom line
Tea offers many health benefits, but too much can cause problems.
Most people can enjoy 3–4 cups (710–950 ml) daily without issues. Beyond that, the caffeine and tannins may lead to anxiety, sleep disruption, digestive discomfort, or reduced iron absorption.
Sensitivity varies. Pay attention to how tea affects you personally. If you notice any unwanted effects, gradually reduce your intake until you find the right balance.
For a caffeine-free alternative, herbal teas made from chamomile, peppermint, or rooibos provide flavor without the stimulant effects.
Delimont NM, Haub MD, Lindshield BL. The Impact of Tannin Consumption on Iron Bioavailability and Status: A Narrative Review. Curr Dev Nutr. 2017;1(2):1-12. PubMed ↩︎
Ahmad Fuzi SF, Koller D, Bruggraber S, Pereira DI, Dainty JR, Mushtaq S. A 1-h time interval between a meal containing iron and consumption of tea attenuates the inhibitory effects on iron absorption. Am J Clin Nutr. 2017;106(6):1413-1421. PubMed ↩︎
Jin MJ, Yoon CH, Ko HJ, et al. Caffeine intake and anxiety: a meta-analysis. Health Psychol Rev. 2024;18(1):135-147. PubMed ↩︎
Gardiner C, Weakley J, Burke LM, et al. The effect of caffeine on subsequent sleep: A systematic review and meta-analysis. Sleep Med Rev. 2023;69:101764. PubMed ↩︎
Chen LW, Wu Y, Neelakantan N, Chong MF, Pan A, van Dam RM. Maternal caffeine intake during pregnancy and risk of pregnancy loss: a categorical and dose-response meta-analysis of prospective studies. Public Health Nutr. 2016;19(7):1233-1244. PubMed ↩︎
Sarah M.
Linda P.
Maya T.
Marcus J.
Emma R.
Amanda K.
Chris B.
David L.
James W.
Jennifer S.
Kevin H.
Lisa C.
App Store ★★★★★
