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Red Bull (250ml / 8.4oz)

Caffeine Half-Life Analysis

For: Pregnancy
80
mg Caffeine
10.5
Hour Half-Life
~N/A
Hours to Sleep-Safe
200
mg Daily Limit

trending_down Caffeine Decay Timeline

How 80mg caffeine clears from your system with a 10.5-hour half-life

Time Elapsed Caffeine Remaining % of Original Status
Now (consumption) 80.0 mg
100.0% 		Moderate
After 1 hour 74.9 mg
93.6% 		Moderate
After 2 hours 70.1 mg
87.6% 		Moderate
After 3 hours 65.6 mg
82.0% 		Moderate
After 4 hours 61.4 mg
76.8% 		Moderate
After 5 hours 57.5 mg
71.9% 		Moderate
After 6 hours 53.8 mg
67.3% 		Moderate
After 8 hours 47.2 mg
59.0% 		Minimal
After 10 hours 41.3 mg
51.7% 		Minimal
After 12 hours 36.2 mg
45.3% 		Minimal
After 16 hours 27.8 mg
34.8% 		Minimal
After 20 hours 21.4 mg
26.7% 		Minimal
After 24 hours 16.4 mg
20.5% 		Minimal

health_and_safety Health Insights for Pregnancy

⚠️ Important Health Consideration

During the third trimester, caffeine half-life can extend to 10-15 hours due to reduced CYP1A2 activity. Caffeine also crosses the placenta.

Daily Limit Calculation

  • • Recommended daily limit: 200mg of caffeine
  • • Caffeine per serving: 80mg
  • • Servings until limit: 2.5 servings

Limit caffeine to 200mg/day (about one 8oz cup of coffee). Consider switching to decaf in the afternoon.

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 10.5 hours for pregnancy, caffeine follows exponential decay:

  • After 10.5 hours: 50% remains (40.0mg)
  • After 21.0 hours: 25% remains (20.0mg)
  • After 31.5 hours: 12.5% remains (10.0mg)
  • After 42.0 hours: 6.25% remains (5.0mg)

The pregnancy category has a slower metabolism compared to healthy adults (5 hours baseline). During the third trimester, caffeine half-life can extend to 10-15 hours due to reduced CYP1A2 activity. Caffeine also crosses the placenta.

warning Important Health Notice

Limit caffeine to 200mg/day (about one 8oz cup of coffee). Consider switching to decaf in the afternoon.

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 Birth Control Users 7.5h 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 pregnancy?

For pregnancy, the caffeine half-life is approximately 10.5 hours. This means that 80mg of caffeine from Red Bull (250ml / 8.4oz) will take about 10.5 hours to reduce to 40mg, and 21.0 hours to drop to 20mg. Full clearance (below 10mg) takes approximately 31.5 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 'Pregnancy' category affect caffeine metabolism?

During the third trimester, caffeine half-life can extend to 10-15 hours due to reduced CYP1A2 activity. Caffeine also crosses the placenta. Limit caffeine to 200mg/day (about one 8oz cup of coffee). Consider switching to decaf in the afternoon.