Energy drinks may be the exception. If you get caffeine from a 32-ounce energy drink, you may be more likely to have abnormal heart rhythms and slightly high blood pressure six hours later. C4 Extreme features the clean & clear formula with 200mg of caffeine content for explosive pre-workout performance. Learn more. Size. 30 Servings 60 Servings. Flavor. Quantity. Ships Free! $38.49 Subscribe & Save 30%. $54.99 One-Time Purchase. Add to cart $38.49. 4 days ago · The strongest, most powerful energy drink is Redline Xtreme (part of the Redline brand from Bang Energy ). This is selected from our database of over 1,000 caffeinated items. With a can size of just 8 fl oz (240 ml), the drink has a massive 316 mg of caffeine. On a caffeine per ounce scale — it is the most powerful. Caffeine Levels. C4 Energy Drink contains 200mg of caffeine per 16 fl oz can. This is a high amount of caffeine, equivalent to two cups of coffee, which can cause jitters, increased heart rate, and insomnia. Other Ingredients. C4 Energy Drink contains various vitamins, amino acids, and natural flavors. PWKw.