How much caffeine should you drink in a day?

Lori Skurbe, RD

Millions of people wake up each morning and the first thing they do is grab a cup of coffee, tea or an energy drink to wake up, as we need the caffeine to start our day. Or maybe it’s the middle of the afternoon and you’ve started to get sleepy or sluggish. You run out to your favorite coffee shop and get a coffee or tea drink for a boost. Whatever the case may be, millions of people drink caffeinated beverages to wake up, get a jump start or to make it through an all-night work or study session. Many people drink multiple cups of coffee, tea, energy drinks and caffeinated colas all day. What are the effects of caffeine and how much might be too much?

What does caffeine do and how much should we have?

Caffeine is a natural stimulant found in coffee, tea and chocolate. It is also added into soft drinks, energy drinks and certain medications. Caffeine stimulates the central nervous system and affects our body in many ways. You may feel more alert, focused and less tired after consuming caffeine. 

For most healthy people, caffeine is not going to harm them, but too much can cause health issues in some individuals. 

Up to 400 mg caffeine per day is safe to have for most adults. Women who are pregnant or breastfeeding should limit caffeine to less than 200 mg per day. Children and adolescents should avoid caffeine. An 8 ounce cup of brewed coffee contains about 96 mg of caffeine, black tea has about 47 mg and colas about 22 mg. An energy “shot” can have as much as 215 mg of caffeine.

For some people caffeine can have unpleasant side effects if you are overly sensitive to caffeine, if you don’t usually ingest caffeine or if taken with other medications. You may need to limit or avoid caffeine if you get:

  • Headaches
  • Cannot sleep (Insomnia)
  • Nervousness
  • Irritability 
  • Increased urination or cannot control urination 
  • Rapid heart beat
  • Muscle tremors 

Medications that can interact with caffeine such as ephedrine (can increase risk of high blood pressure, heart attack, stroke or seizure) theophylline (can increase risk of nausea or heart palpitations) or echinacea (can increase the concentration of caffeine in our blood leading to unpleasant side effects). 

On the other hand, caffeine can have positive effects. If you are getting your caffeine from coffee or tea, these foods also contain antioxidants and other substances that may play a role in decreasing inflammation and protecting against diseases.

If you feel you need to cut down, do so slowly, as abrupt cessation of caffeine can lead to withdrawal symptoms such as headache, fatigue, irritability and difficulty focusing. These usually go away in a few days and are usually mild.

Try switching to decaf teas, colas or coffee. Check medications for caffeine that may be added in to make sure you are limiting the amount of caffeine you take in each day. 

As with most foods and beverages, moderation is key.  All foods can fit into a healthy diet, but we must be mindful of how much we take in.