The Mayo Clinic also warns against certain medications and herbal supplements that may interact with caffeine and cause bad reactions that can become deadly.
Ephedrine: Mixing caffeine with this medication commonly used in decongestants might increase the risk of high blood pressure, heart attack, stroke or seizure.
Theophylline: This medication, used in Theo-24 and Elixophyllin, is used to open bronchial airways. Taking it with caffeine can increase the adverse effects of caffeine, since the two drugs have similar effects. Nausea and heart palpitations are possible effects if you mix the two.
Echinacea: This herbal supplement, which people may take to prevent colds or other infections, may also increase the concentration of caffeine in your blood, along with amplifying the unpleasant effects of other caffeine consumed.
How much is too much caffeine?
Whether you're sipping a delicious latte or downing an energy shot from the convenience store, there is a safe amount of daily caffeine consumption. According to the Mayo Clinic, the number to strive for is 400 milligrams, which is roughly the amount of caffeine in four cups of brewed coffee, 10 cans of cola or two energy shots.
Some people are more sensitive, the Mayo Clinic noted, and for them even one cup of tea or coffee may prompt restlessness, sleep problems or other negative effects. Your reaction to caffeine can also depend on how much you're used to drinking − those with an established habit may be able to drink more without the unwanted side effects.
Men's Health featured a formula that helps consumers figure out how much caffeine would put them over that daily limit, which basically relies on dividing the caffeine milligrams in a source by 400. A Starbucks brew coffee, for example, with 320 milligrams, would indicate 1.2 cups for the daily safe limit.
You do need to time the caffeine you consume for maximum benefit, according to Men's Health, since caffeine takes 30-45 minutes to kick in regardless of what caffeine product you consume.
When you drink more than 4 cups of coffee per day or the equivalent, these side effects might mean you should cut back on caffeine, according to the Mayo Clinic:
• Migraine headache
• Insomnia
• Nervousness
• Irritability
• Restlessness
• Frequent urination or inability to control urination
• Stomach upset
• Fast heartbeat
• Muscle tremors
If you suspect caffeine overdose or any other sort of poisoning, you can reach your local poison center directly by calling the national toll-free poison help hotline (1-800-222-1222) from anywhere in the United States.
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