Caffeine is a bitter substance found naturally in coffee, tea, cola and chocolate that stimulates your central nervous system and helps you feel more awake2.
Stimulates your central nervous system, which can make you feel more awake2.
Its main action is blocking adenosine receptors in the body, including the brain3.
Helps your body get rid of extra salt and water by urinating more2.
Can raise blood pressure, and too much can speed up your heart rate2.
Increases the release of acid in your stomach2.
| Food and serving | Amount |
|---|---|
| Coffee, brewed, 12 fl oz | 113–247 mg |
| Energy drink, 12 fl oz | 41–246 mg |
| Black tea, 12 fl oz | 71 mg |
| Green tea, 12 fl oz | 37 mg |
| Caffeinated soft drink, 12 fl oz | 23–83 mg |
| Decaf coffee, 8 fl oz | 2–15 mg |
Amounts vary widely by brand, brew and serving size, and energy drink labels may not show how much caffeine they contain2. Amounts per serving from1.
The same reference table draws the reference lines on your charts in Ayuvo. Needs differ in pregnancy and breastfeeding, which are not covered here.
Signs like these have many possible causes. They are a reason to talk to a clinician, not to self-treat.
Stopping suddenly after regular use can bring short-lived withdrawal symptoms that usually go away after a couple of days2.
Too much caffeine can cause side effects, and people vary widely in how sensitive they are and how fast they clear it1.
Caffeine reaches its peak level in your blood within about an hour, and you may feel its effects for four to six hours. About half of it has been cleared after three to five hours, but this varies a lot between people.
A 12-ounce cup of regular brewed coffee has about 113 to 247 mg of caffeine, depending on the beans and how it is brewed. An 8-ounce cup of decaf still has about 2 to 15 mg.
Withdrawal is not considered dangerous, but it can bring headaches, drowsiness, irritability, nausea and trouble concentrating. These usually ease after a couple of days, and cutting back gradually can help.
Ayuvo charts caffeine by day, week, month and year, with the reference lines from this page, personalised by age and sex where they differ. Supplements you log in Medications count too. Free, with no account.
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Facts on this page come from these sources, checked on the dates shown. Intake numbers come from Ayuvo's shared reference table, which cites the sources marked for them.
General information, not medical advice. This guide is for healthy adults and does not cover pregnancy, breastfeeding, children or medical conditions. It cannot diagnose or treat anything. Talk to a clinician before starting high-dose supplements, or if you think you may have too little or too much of a nutrient. Spotted an error? Email us.