Children: Caffeine is POSSIBLY SAFE when taken appropriately by mouth or intravenously (by IV), as well as when used in amounts commonly found in foods and beverages.
Pregnancy and breastfeeding: Caffeine is POSSIBLY SAFE in pregnant or breast-feeding women when used daily amounts of less than 200 mg. This is about the amount in 1-2 cups of coffee. Consuming larger amounts during pregnancy or when breast-feeding is POSSIBLY UNSAFE. When consumed in larger amounts during pregnancy, caffeine might increase the chance of miscarriage and other problems. Also, caffeine can pass into breast milk, so nursing mothers should closely monitor caffeine intake to make sure it is on the low side. High intake of caffeine by nursing mothers can cause sleep disturbances, irritability, and increased bowel activity in breast-fed infants.
Anxiety disorders: Caffeine might make these conditions worse. Use with care.
Bipolar disorder: Too much caffeine might make this condition worse. In one case, a 36-year-old man with controlled bipolar disorder was hospitalized with symptoms of mania after drinking several cans of an energy drink containing caffeine, taurine, inositol, and other ingredients (Red Bull Energy Drink) over a period of 4 days. Use caffeine with care and in low amounts if you have bipolar disorder.
Bleeding disorders: There is concern that caffeine might aggravate bleeding disorders. Use caffeine with care if you have a bleeding disorder.
Heart conditions: Caffeine can cause irregular heartbeat in sensitive people. Use caffeine with caution.
Diabetes: Some research suggests that caffeine may affect the way the body uses sugar and might worsen diabetes. However, the effect of caffeinated beverages and supplements has not been studied. If you have diabetes, use caffeine with caution.
Diarrhea: Caffeine, especially when taken in large amounts, can worsen diarrhea.
Epilepsy: People with epilepsy should avoid using caffeine in high doses. Low doses of caffeine should be used cautiously.
Glaucoma: Caffeine increases the pressure inside the eye. The increase occurs within 30 minutes and lasts for at least 90 minutes after drinking caffeinated beverages.
High blood pressure: Consuming caffeine might increase blood pressure in people with high blood pressure. However, this effect might be less in people who use caffeine regularly.
Irritable bowel syndrome (IBS): Caffeine, especially when taken in large amounts, can worsen diarrhea and might worsen symptoms of IBS.
Weak bones (osteoporosis): Caffeine can increase the amount of calcium that is flushed out in the urine. If you have osteoporosis or low bone density, caffeine should be limited to less than 300 mg per day (approximately 2-3 cups of coffee). It is also a good idea to get extra calcium to make up for the amount that may be lost in the urine. Older women with an inherited disorder that affects the way vitamin D is used should use caffeine with caution. Vitamin D works with calcium to build bones.
MAJOR INTERACTION: DO NOT TAKE THIS COMBINATION
Ephedrine interacts with CAFFEINE
Stimulant drugs speed up the nervous system. Caffeine and ephedrine are both stimulant drugs. Taking caffeine along with ephedrine might cause too much stimulation and sometimes serious side effects and heart problems. Do not take caffeine-containing products and ephedrine at the same time.