What Happens to Your Body When You Drink Too Much Green Tea

Drinking too much green tea can potentially cause some adverse effects. Credit: ninavartanava / Getty Images

Green tea is packed with health benefits, but drinking more than 4 or 5 cups a day may do more harm than good. Consider evaluating your daily intake of brewed green tea, especially if you also consume other sources of caffeine.

1. You May Feel Jittery or Nervous

Green tea’s caffeine may boost alertness, but can also cause jitters or anxiety. This may be due to:

• Caffeine content: Too much caffeine may trigger restlessness or anxiety.^1,2 Avoid tea at least six hours before bedtime to reduce insomnia risk.³
• Caffeine sensitivity: Some individuals may experience overstimulation even with small amounts, depending on how their bodies process caffeine.⁴
• Medication interactions: Caffeine may increase stimulant effects or reduce how well anti-anxiety medications and sleep aids work.⁵

However, green tea also contains the amino acid L-theanine, which promotes calmness and may help counteract the stimulating effects of caffeine.⁶

Recommended Safe Daily Caffeine Limits Across Population Groups
Group	Daily Caffeine Limit
Adults	Up to 400 milligrams (mg)
Pregnancy or Breastfeeding	Around 200 mg2
Children 12–18	Limit to less than 100 mg/day (e.g., two 12 oz colas). Avoid all energy drinks.
Children Under 12	Avoid all caffeine, including energy drinks7

Green tea contains 20–45 mg of caffeine per 6 to 8 oz (177–237 milliliter, mL) serving.

2. Your Heart Rate and Blood Pressure May Rise

Green tea supports heart health, but may temporarily raise heart rate and blood pressure due to its caffeine content. These effects are more likely if you're caffeine-sensitive or drink more than about 4-5 cups a day.⁸

Combining green tea with medications or supplements such as the following may increase potential cardiovascular risks:⁹

• Stimulants (e.g., ADHD medications)
• Blood pressure medications, such as ACE inhibitors (e.g., lisinopril), beta-blockers, and calcium channel blockers
• Over-the-counter cold medicines
• Supplements like ginseng or guarana^10,11

Consult your healthcare provider before incorporating green tea into your routine, especially if you are taking medications or have a pre-existing heart condition.

3. Your Digestion and Medication Absorption May Change

Drinking green tea may do more than soothe—too much may impact your digestion and how your body absorbs medications and nutrients. Here's what you need to know:

• Appetite changes: Green tea may slightly reduce appetite, possibly due to its caffeine, catechins, or increased fluid volume. However, research on this effect is mixed.¹²
• Gut symptoms: Tannins and catechins—affected by steeping time and water temperature—may cause nausea, especially on an empty stomach.^13,14,13 Some studies also report reflux or diarrhea.^15,16
• Liver safety: Drinking large amounts of brewed green tea (several liters daily) may raise your risk of liver injury. Avoid excessive intake.¹⁷
• Medication absorption issues: Green tea may reduce the absorption and effectiveness of specific medications, including select beta-blockers, raloxifene, statins, and those that affect the immune system (such as methotrexate and cyclosporine).^18,9
• Nutrient absorption concerns: Green tea may reduce iron absorption.¹⁹ Aim to drink green tea 1-2 hours before or after meals. In rare cases, large amounts caused low potassium levels (hypokalemia).²⁰

Consult your healthcare provider before drinking green tea regularly, especially if you have a pre-existing health condition or are taking prescription medications.

Important Notice: This article was originally published at www.verywellhealth.com by Regina Windsor, MPH, RDN, where all credits are due.

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