For so many people, caffeine is the substance you turn to in the morning and anytime you need a pick-me-up, and it's found in an array of favorite beverages and foods, including coffee, tea, soda and even chocolate. However, caffeine can come with adverse effects, such as nausea, in some people.
Caffeine Side Effects
Caffeine, which is a naturally occurring stimulant, is usually absorbed into your system within 30 minutes, according to a January 2014 review in the journal Food Science and Quality Management. It passes quickly into the brain, is metabolized in the liver and then filtered by your kidneys.
The amount of time it takes to leave the body depends on the individual, the journal article notes. Caffeine can stay in an average adult's system for three to five hours, a pregnant woman's for seven to eight hours and a smoker's for two to three hours.
It's important to keep tabs on how much caffeine you're consuming each day. Mayo Clinic states that up to 400 milligrams of caffeine a day is a safe amount for most healthy adults. If you tend to take in more than that, you may want to consider cutting back if you experience the following side effects:
- Nausea and vomiting
- Fast heartbeat
- Frequent urination
About Caffeine Sensitivity
If you've noticed that drinking coffee makes you nauseous, it's possible you have some sensitivity to caffeine. "Multiple factors can contribute to caffeine sensitivity," says Leah Heck, RDN, a registered dietitian nutritionist in Ann Arbor, Michigan.
"Because a person's age and weight can lead to changes in the rate of caffeine metabolism, it's possible for someone to feel the effects of caffeine differently throughout their lives and lead them to believe that they're experiencing a sudden development of caffeine sensitivity," Heck says.
Studies have shown that caffeine sensitivity can occur due to certain genes. According to an October 2018 review in the journal Nutrients, CYP1A2 and ADORA2A genes are thought to have the biggest impact when it comes to caffeine. CYP1A2 deals with the metabolism of caffeine, and ADORA2A is believed to be linked with anxiety induced by caffeine.
The CYP1A2 gene is found in the liver and associated with 95 percent of caffeine metabolism, according to research published in April 2018 in Pharmacological Reviews. The activity of this gene can vary based on sex, race, genetics and any diseases you have.
Nausea may seem worse after drinking coffee on an empty stomach. According to the Cleveland Clinic, caffeine releases acid in the stomach, which results in heartburn and indigestion. Ensuring that you eat while drinking caffeine will help to offset those side effects.
Caffeine sensitivity can increase during pregnancy. If you're pregnant, you may notice signs of nausea, feel jittery or have trouble sleeping if you have any caffeine. The March of Dimes states this sensitivity stems from the body taking longer to clear this stimulant when you are pregnant. It recommends limiting the amount of caffeine to 200 milligrams a day during pregnancy to avoid any negative side effects.
It's important to note that caffeine can also pass into breast milk post-pregnancy. Continuing to limit it while breastfeeding will help to reduce side effects your baby may encounter, such as fussiness or trouble sleeping, says March of Dimes.
Reversing Caffeine's Effects
If you've had too much caffeine, the only remedy is to wait for your body to metabolize it. As you wait for the symptoms to pass, stay hydrated and avoid consuming any additional caffeine from hidden sources — always check the ingredients list on food and beverage labels.
If you want to decrease your caffeine in the future, keep track of how much you have in a journal, suggests the Mayo Clinic. Begin decreasing caffeine gradually so your body gets used to the lower amount over time without withdrawal symptoms like a headache. Decaffeinated beverages are an option to consider. While they still contain caffeine, it's a much lower amount compared to their regular counterparts.
- Food Science and Quality Management: “Effects of Caffeine on Health and Nutrition: A Review”
- Mayo Clinic: “Caffeine: How Much Is Too much?”
- Leah Heck, RDN, registered dietitian nutritionist, Ann Arbor, Michigan
- Nutrients: “The Role of Genetics in Moderating the Inter-Individual Differences in the Ergogenicity of Caffeine”
- Pharmacological Reviews: “Interindividual Differences in Caffeine Metabolism and Factors Driving Caffeine Consumption”
- March of Dimes: “Caffeine in Pregnancy”
- Cleveland Clinic: “Caffeine: Tips for Breaking the Habit”