In This ArticleView AllIn This ArticleWhat Is Caffeine?Medication InteractionsWho Should Avoid ItSide EffectsHow Much Is Safe
In This ArticleView All
View All
In This Article
What Is Caffeine?
Medication Interactions
Who Should Avoid It
Side Effects
How Much Is Safe
Close
Photo:Andrea_Dawn/Getty Images
Andrea_Dawn/Getty Images
Caffeine is an essential part of many people’s daily routines. Whether in the form of a morning cup of coffee, an afternoon pick-me-up or a soda with dinner, caffeine is a widely consumed stimulant that can impact your body in various ways.
Alongside its energizing qualities, caffeine has a complex relationship with medications that shouldn’t be overlooked. Understanding how caffeine interacts with certain medications is critical for managing your health effectively and avoiding potential complications. Here, we’ll cover caffeine’s impact on certain medications, discuss its potential risks and side effects, and provide expert guidance for safe caffeine consumption. Keep reading to learn more.
Caffeine is a natural stimulant that belongs to a class of compounds called xanthines, and it’s the most widely consumed psychoactive drug in the world.It’s most commonly found in coffee beans, tea leaves, cacao beans and kola nuts.Caffeine is also added to many common beverages and supplements, likeenergy drinks, sodas andpre-workout supplements.
Drinking caffeine works on your brain to keep you awake and alert, pushing back feelings of tiredness. It can help you feel more focused, stay more alert and even perform better physically, which is why so many people turn to it for a quick pick-me-up. However, caffeine should be consumed in moderation, as too much can lead to adverse effects such as restlessness, anxiety and insomnia.
4 Ways Caffeine Can Impact Your Medications
While caffeine is a widely beloved stimulant touted for its energizing effects and health benefits, Harris-Pincus cautions that caffeine’s positive qualities may be influenced when combined with certain drugs or medications, stating, “Caffeine may increase or decrease the effectiveness of certain medications, depending on how the drugs are metabolized.”
1. May Increase Bleeding Risk with Blood Thinners
2. Could Reduce Thyroid Medication Absorption
Harris-Pincus says that caffeine consumption can interfere with the absorption of certainthyroidmedications, such as levothyroxine (Synthroid), used to treat hypothyroidism. Caffeine may reduce the absorption of levothyroxine in the gastrointestinal tract, leading to reduced effectiveness, suggests a 2022 study.
3. May Intensify ADHD Medication Effects
Medications like methylphenidate (Ritalin) and amphetamine (Adderall) are commonly prescribed to help improve focus and concentration in those withattention deficit/hyperactivity disorder. However, caffeine can interact with these medications and may increase their stimulant effects.“Meds for ADHD, such as Adderall and Ritalin, combined with caffeine can increase feelings of anxiety, insomnia, jitters and potential heart problems,” says Harris-Pincus.
4. Could Alter Estrogen Levels with Oral Contraceptives
According to the National Institutes of Health, caffeine can interact with oral contraceptives and impact how your body metabolizes estrogen. Some studies suggest that caffeine may increase estrogen levels in women taking oral contraceptives.Harris-Pincus tells us, “Oral contraceptives can inhibit the enzyme responsible for breaking down caffeine so that you may feel prolonged or more significant effects.”
Related:What Happens to Your Body When You Drink Coffee Every Day
Who Should Avoid Caffeine?
“Those with high blood pressure, heart arrhythmias, gastroesophageal reflux, migraines, sleep disorders, taking certain medications or are pregnant or breastfeeding should speak with their doctor about how much caffeine is advisable for them to consume,” says Harris-Pincus.
Related:What Happens to Your Body When You Drink Coffee During Your Menstrual Cycle
Side Effects of Caffeine Supplements
Common side effects of caffeine supplements include jitteriness, nervousness, restlessness and increased heart rate. Some people may also experience gastrointestinal issues such as stomach upset, diarrhea oracid reflux. In some cases, consuming large amounts of caffeine can lead to caffeine overdose, also known as caffeine toxicity. Symptoms of caffeine overdose include dizziness, rapid or irregular heartbeat, anxiety, fever and nausea.
“Some people are sensitive to caffeine and may experience unpleasant side effects like jitters, nausea, an increase in heart rate and blood pressure, trouble sleeping or anxiety,” says Harris-Pincus.
How Much Caffeine per Day Is Safe?
While there’s no specific daily recommended intake forcaffeine, the NIH states that doses of up to 400 milligrams a day are considered safe.However, caffeine sensitivity can vary widely depending on factors such as age, sex and weight. Some people may experience side effects at lower doses, while others may tolerate higher amounts without issue.
“The consensus is to limit total caffeine intake to 400 milligrams per day for adults, assuming you are not sensitive to its stimulant effects. An 8-ounce cup of coffee can contain anywhere from 95 to 200 milligrams of caffeine, a can of cola has around 40 milligrams, and a cup of tea contains 14 to 60 milligrams,” says Harris-Pincus.
Related:How Much Caffeine Is Too Much? Here’s What a Dietitian Has to Say
The Bottom Line
Caffeine is one of the world’s most widely consumed and enjoyed dietary compounds. However, caffeine can interact with certain medications. Being aware of these interactions is essential, as they can impact the effectiveness and safety of your medical treatment. Caffeine may affect the absorption, metabolism or side effects of certain medications, including blood thinners, oral contraceptives and medications for the thyroid and ADHD. If you’re taking any medications, speak with your health care provider or pharmacist about how caffeine may interact with your medication regimen. If you need to limit your caffeine intake, there are many other beverages and foods you can enjoy instead, such as herbal teas,decaffeinated coffeeor caffeine-free soft drinks.
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SourcesEatingWell uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable and trustworthy.Temple JL, Bernard C, Lipshultz SE, et al.The Safety of Ingested Caffeine: A Comprehensive Review.Frontiers in Psychiatry. 2017;8:80. doi: 10.3389/fpsyt.2017.00080.National Library of Medicine.Caffeine - StatPearls.Jee HJ, Lee SG, Bormate KJ, Jung YS.Effect of Caffeine Consumption on the Risk for Neurological and Psychiatric Disorders: Sex Differences in Human.Nutrients. 2020;12(10):3080. doi: 10.3390/nu12103080.National Library of Medicine.Warfarin - StatPearls.Zafar S, Ashraf MM, Ali A, et al.Effect of caffeine on anti-clotting activity of warfarin in healthy male albino rabbits.Pakistan Journal of Pharmceutical Sciences. 2018;31(2(Suppl.)):611-616. PMID: 29625932.Lai YW, Huang SM.Tea consumption affects the absorption of levothyroxine.Frontiers in Endocrinology. 2022;13:943775. doi: 10.3389/fendo.2022.943775.Hladun O, Papaseit E, Martín S, et al.Interaction of Energy Drinks with Prescription Medication and Drugs of Abuse.Pharmaceutics. 2021;13(10):1532. doi: 10.3390/pharmaceutics13101532National Library of Medicine.Pharmacology of Caffeine.Lakin H, Sheehan P, Soti V.Maternal Caffeine Consumption and Its Impact on the Fetus: A Review.Cureus. 2023;15(11):e48266. doi: 10.7759/cureus.48266.Mehta RS, Song M, Staller K, Chan AT.Association Between Beverage Intake and Incidence of Gastroesophageal Reflux Symptoms.Clinical Gastroenterology and Hepatology. 2020;18(10):2226-2233.e4. doi: 10.1016/j.cgh.2019.11.040.Pina Cabral J, Sousa DL, Carvalho C, et al.Caffeine Intoxication: Unregulated, Over-the-Counter Sale of Potentially Deadly Supplements.Cureus. 2022;14(1):e21045. doi: 10.7759/cureus.21045.
Sources
EatingWell uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable and trustworthy.Temple JL, Bernard C, Lipshultz SE, et al.The Safety of Ingested Caffeine: A Comprehensive Review.Frontiers in Psychiatry. 2017;8:80. doi: 10.3389/fpsyt.2017.00080.National Library of Medicine.Caffeine - StatPearls.Jee HJ, Lee SG, Bormate KJ, Jung YS.Effect of Caffeine Consumption on the Risk for Neurological and Psychiatric Disorders: Sex Differences in Human.Nutrients. 2020;12(10):3080. doi: 10.3390/nu12103080.National Library of Medicine.Warfarin - StatPearls.Zafar S, Ashraf MM, Ali A, et al.Effect of caffeine on anti-clotting activity of warfarin in healthy male albino rabbits.Pakistan Journal of Pharmceutical Sciences. 2018;31(2(Suppl.)):611-616. PMID: 29625932.Lai YW, Huang SM.Tea consumption affects the absorption of levothyroxine.Frontiers in Endocrinology. 2022;13:943775. doi: 10.3389/fendo.2022.943775.Hladun O, Papaseit E, Martín S, et al.Interaction of Energy Drinks with Prescription Medication and Drugs of Abuse.Pharmaceutics. 2021;13(10):1532. doi: 10.3390/pharmaceutics13101532National Library of Medicine.Pharmacology of Caffeine.Lakin H, Sheehan P, Soti V.Maternal Caffeine Consumption and Its Impact on the Fetus: A Review.Cureus. 2023;15(11):e48266. doi: 10.7759/cureus.48266.Mehta RS, Song M, Staller K, Chan AT.Association Between Beverage Intake and Incidence of Gastroesophageal Reflux Symptoms.Clinical Gastroenterology and Hepatology. 2020;18(10):2226-2233.e4. doi: 10.1016/j.cgh.2019.11.040.Pina Cabral J, Sousa DL, Carvalho C, et al.Caffeine Intoxication: Unregulated, Over-the-Counter Sale of Potentially Deadly Supplements.Cureus. 2022;14(1):e21045. doi: 10.7759/cureus.21045.
EatingWell uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable and trustworthy.
Temple JL, Bernard C, Lipshultz SE, et al.The Safety of Ingested Caffeine: A Comprehensive Review.Frontiers in Psychiatry. 2017;8:80. doi: 10.3389/fpsyt.2017.00080.National Library of Medicine.Caffeine - StatPearls.Jee HJ, Lee SG, Bormate KJ, Jung YS.Effect of Caffeine Consumption on the Risk for Neurological and Psychiatric Disorders: Sex Differences in Human.Nutrients. 2020;12(10):3080. doi: 10.3390/nu12103080.National Library of Medicine.Warfarin - StatPearls.Zafar S, Ashraf MM, Ali A, et al.Effect of caffeine on anti-clotting activity of warfarin in healthy male albino rabbits.Pakistan Journal of Pharmceutical Sciences. 2018;31(2(Suppl.)):611-616. PMID: 29625932.Lai YW, Huang SM.Tea consumption affects the absorption of levothyroxine.Frontiers in Endocrinology. 2022;13:943775. doi: 10.3389/fendo.2022.943775.Hladun O, Papaseit E, Martín S, et al.Interaction of Energy Drinks with Prescription Medication and Drugs of Abuse.Pharmaceutics. 2021;13(10):1532. doi: 10.3390/pharmaceutics13101532National Library of Medicine.Pharmacology of Caffeine.Lakin H, Sheehan P, Soti V.Maternal Caffeine Consumption and Its Impact on the Fetus: A Review.Cureus. 2023;15(11):e48266. doi: 10.7759/cureus.48266.Mehta RS, Song M, Staller K, Chan AT.Association Between Beverage Intake and Incidence of Gastroesophageal Reflux Symptoms.Clinical Gastroenterology and Hepatology. 2020;18(10):2226-2233.e4. doi: 10.1016/j.cgh.2019.11.040.Pina Cabral J, Sousa DL, Carvalho C, et al.Caffeine Intoxication: Unregulated, Over-the-Counter Sale of Potentially Deadly Supplements.Cureus. 2022;14(1):e21045. doi: 10.7759/cureus.21045.
Temple JL, Bernard C, Lipshultz SE, et al.The Safety of Ingested Caffeine: A Comprehensive Review.Frontiers in Psychiatry. 2017;8:80. doi: 10.3389/fpsyt.2017.00080.
National Library of Medicine.Caffeine - StatPearls.
Jee HJ, Lee SG, Bormate KJ, Jung YS.Effect of Caffeine Consumption on the Risk for Neurological and Psychiatric Disorders: Sex Differences in Human.Nutrients. 2020;12(10):3080. doi: 10.3390/nu12103080.
National Library of Medicine.Warfarin - StatPearls.
Zafar S, Ashraf MM, Ali A, et al.Effect of caffeine on anti-clotting activity of warfarin in healthy male albino rabbits.Pakistan Journal of Pharmceutical Sciences. 2018;31(2(Suppl.)):611-616. PMID: 29625932.
Lai YW, Huang SM.Tea consumption affects the absorption of levothyroxine.Frontiers in Endocrinology. 2022;13:943775. doi: 10.3389/fendo.2022.943775.
Hladun O, Papaseit E, Martín S, et al.Interaction of Energy Drinks with Prescription Medication and Drugs of Abuse.Pharmaceutics. 2021;13(10):1532. doi: 10.3390/pharmaceutics13101532
National Library of Medicine.Pharmacology of Caffeine.
Lakin H, Sheehan P, Soti V.Maternal Caffeine Consumption and Its Impact on the Fetus: A Review.Cureus. 2023;15(11):e48266. doi: 10.7759/cureus.48266.
Mehta RS, Song M, Staller K, Chan AT.Association Between Beverage Intake and Incidence of Gastroesophageal Reflux Symptoms.Clinical Gastroenterology and Hepatology. 2020;18(10):2226-2233.e4. doi: 10.1016/j.cgh.2019.11.040.
Pina Cabral J, Sousa DL, Carvalho C, et al.Caffeine Intoxication: Unregulated, Over-the-Counter Sale of Potentially Deadly Supplements.Cureus. 2022;14(1):e21045. doi: 10.7759/cureus.21045.
