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Green Tea (240ml / 8oz)

Caffeine Half-Life Analysis

For: Birth Control Users
28
mg Caffeine
7.5
Hour Half-Life
~N/A
Hours to Sleep-Safe
400
mg Daily Limit

trending_down Caffeine Decay Timeline

How 28mg caffeine clears from your system with a 7.5-hour half-life

Time Elapsed Caffeine Remaining % of Original Status
Now (consumption) 28.0 mg
100.0% 		Minimal
After 1 hour 25.5 mg
91.2% 		Minimal
After 2 hours 23.3 mg
83.1% 		Minimal
After 3 hours 21.2 mg
75.8% 		Minimal
After 4 hours 19.3 mg
69.1% 		Minimal
After 5 hours 17.6 mg
63.0% 		Minimal
After 6 hours 16.1 mg
57.4% 		Minimal
After 8 hours 13.4 mg
47.7% 		Minimal
After 10 hours 11.1 mg
39.7% 		Minimal
After 12 hours 9.2 mg
33.0% 		Cleared
After 16 hours 6.4 mg
22.8% 		Cleared
After 20 hours 4.4 mg
15.7% 		Cleared
After 24 hours 3.0 mg
10.9% 		Cleared

health_and_safety Health Insights for Birth Control Users

⚠️ Important Health Consideration

Estrogen in birth control pills inhibits CYP1A2 enzymes, extending caffeine's half-life by 30-50%. This effect is more pronounced with higher estrogen doses.

Daily Limit Calculation

  • • Recommended daily limit: 400mg of caffeine
  • • Caffeine per serving: 28mg
  • • Servings until limit: 14.3 servings

Reduce afternoon caffeine intake. The same amount of coffee will have a stronger, longer-lasting effect.

Sleep Quality Impact

Caffeine blocks adenosine receptors in the brain, preventing the buildup of sleep pressure. Even when you don't feel "wired," residual caffeine can reduce deep sleep quality by up to 20%.

>100mg
May disrupt sleep
50-100mg
Reduced deep sleep
<50mg
Minimal impact

science How Caffeine Half-Life Works

Half-life is the time required for the body to eliminate 50% of a substance. For caffeine, this primarily occurs in the liver through the CYP1A2 enzyme system.

With a half-life of 7.5 hours for birth control users, caffeine follows exponential decay:

  • After 7.5 hours: 50% remains (14.0mg)
  • After 15.0 hours: 25% remains (7.0mg)
  • After 22.5 hours: 12.5% remains (3.5mg)
  • After 30.0 hours: 6.25% remains (1.75mg)

The birth control users category has a slower metabolism compared to healthy adults (5 hours baseline). Estrogen in birth control pills inhibits CYP1A2 enzymes, extending caffeine's half-life by 30-50%. This effect is more pronounced with higher estrogen doses.

warning Please Note

Reduce afternoon caffeine intake. The same amount of coffee will have a stronger, longer-lasting effect.

Compare Other Drinks

Brewed Coffee (240ml / 8oz) 95mg Espresso (30ml / 1oz shot) 63mg Red Bull (250ml / 8.4oz) 80mg Monster Energy (473ml / 16oz) 160mg

Compare Conditions

Healthy Adult 5.0h Smokers 3.0h Pregnancy 10.5h Liver Impairment 12.0h Elderly (65+) 6.5h Fast Metabolizers (Genetic) 3.5h

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About Green Tea (240ml / 8oz)

Brewed green tea

Note: Contains L-theanine which modulates caffeine's effects

help Frequently Asked Questions

How long does Green Tea (240ml / 8oz) caffeine last for birth control users?

For birth control users, the caffeine half-life is approximately 7.5 hours. This means that 28mg of caffeine from Green Tea (240ml / 8oz) will take about 7.5 hours to reduce to 14mg, and 15.0 hours to drop to 7mg. Full clearance (below 10mg) takes approximately 11.1 hours.

When should I stop drinking Green Tea (240ml / 8oz) to sleep well?

If you plan to sleep at 10 PM, you should consume your last Green Tea (240ml / 8oz) by any time - caffeine level is low. This allows approximately sufficient hours for caffeine levels to drop below the sleep disruption threshold of 100mg.

How does being in the 'Birth Control Users' category affect caffeine metabolism?

Estrogen in birth control pills inhibits CYP1A2 enzymes, extending caffeine's half-life by 30-50%. This effect is more pronounced with higher estrogen doses. Reduce afternoon caffeine intake. The same amount of coffee will have a stronger, longer-lasting effect.