Green tea is a beverage considered by many to be supremely healthy. Diets, health plans, and weight loss regimens all include green tea as a beneficial component. Though non-toxic, green tea side effects can occur when consumed in substantial quantities. To avoid any possible side effects, most health experts recommend drinking only one or two cups per day of green tea.

Most green tea side effects are related to the relatively high caffeine content in most green tea beverages and supplements. Similar to coffee or espresso, green tea can cause anxiety, sleeplessness, a feeling of hyperactivity, rapid heart rate, and increased blood pressure. Children and people with medical conditions adversely affected by these green tea side effects are typically told to avoid the product or drink in limited quantities.

Certain medical conditions may make green tea side effects more likely and potentially harmful. Some experts recommend discussing green tea intake with a doctor or health care professional if kidney problems, hyperthyroid disorder, anxiety issues, or blood disorders are present. Most of these complications are related to caffeine content, and can sometimes be avoided by drinking decaffeinated green tea.

There is some evidence that it is possible to overdose on green tea, particularly if a large amount of concentrated green tea supplements are ingested. Symptoms and signs of an overdose may include pounding heart rate, excess sweating, vomiting, and abdominal pain or spasms. Experts recommend contacting emergency medical help or poison control immediately if an overdose occurs.

Some green tea side effects are related to other properties of the tea. Green tea is typically a pale tan or green color, and can stain the teeth if not properly cleaned. Be sure to brush teeth at least twice a day to avoid staining, or brush after each glass of green tea to promptly remove stains.

Although rare, green tea side effects include allergic reactions. Symptoms may include hives or a rash, swelling of the face or throat, and difficulty breathing. If swelling or breathing problems occur, consult a doctor immediately. A person may also wish to consult with an allergy specialist to do further testing to determine if an allergy to green tea exists.

Typically, green tea can be a tasty drink loaded with antioxidants. Some advocates claim that the beverage is extremely beneficial to weight loss and makes a better caffeinated choice than coffee or energy drinks. To avoid green tea side effects, drink or take supplements in moderate doses, and stop consuming if any side effects are experienced.