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Red Bull (250ml / 8.4oz)

Caffeine Half-Life Analysis

For: Birth Control Users
80
mg Caffeine
7.5
Hour Half-Life
~N/A
Hours to Sleep-Safe
400
mg Daily Limit

trending_down Caffeine Decay Timeline

How 80mg caffeine clears from your system with a 7.5-hour half-life

Time Elapsed Caffeine Remaining % of Original Status
Now (consumption) 80.0 mg
100.0% 		Moderate
After 1 hour 72.9 mg
91.2% 		Moderate
After 2 hours 66.5 mg
83.1% 		Moderate
After 3 hours 60.6 mg
75.8% 		Moderate
After 4 hours 55.3 mg
69.1% 		Moderate
After 5 hours 50.4 mg
63.0% 		Moderate
After 6 hours 45.9 mg
57.4% 		Minimal
After 8 hours 38.2 mg
47.7% 		Minimal
After 10 hours 31.7 mg
39.7% 		Minimal
After 12 hours 26.4 mg
33.0% 		Minimal
After 16 hours 18.2 mg
22.8% 		Minimal
After 20 hours 12.6 mg
15.7% 		Minimal
After 24 hours 8.7 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: 80mg
  • • Servings until limit: 5.0 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 (40.0mg)
  • After 15.0 hours: 25% remains (20.0mg)
  • After 22.5 hours: 12.5% remains (10.0mg)
  • After 30.0 hours: 6.25% remains (5.0mg)

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 Monster Energy (473ml / 16oz) 160mg Green Tea (240ml / 8oz) 28mg

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 Red Bull (250ml / 8.4oz)

Popular energy drink

Note: Also contains taurine, B-vitamins, and 27g of sugar

help Frequently Asked Questions

How long does Red Bull (250ml / 8.4oz) caffeine last for birth control users?

For birth control users, the caffeine half-life is approximately 7.5 hours. This means that 80mg of caffeine from Red Bull (250ml / 8.4oz) will take about 7.5 hours to reduce to 40mg, and 15.0 hours to drop to 20mg. Full clearance (below 10mg) takes approximately 22.5 hours.

When should I stop drinking Red Bull (250ml / 8.4oz) to sleep well?

If you plan to sleep at 10 PM, you should consume your last Red Bull (250ml / 8.4oz) 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.