Anything in excess is always harmful to the human body, despite the fact that it may be a health food. Herbal teas are beneficial and have healing properties, having too much will cause medical issues.
Heartburn, upset stomach, nausea, vomiting, diarrhoea and gas can be caused if you overdose on lemongrass, ginger, camomile, thyme, star anise, clove, mint or aloe vera tea.
Cinnamon tea overdose causes liver damage and toxicity. Excess consumption of basil tea leads to lowered libido and also affects production of sperm. Overconsumption of lavender tea may cause drowsiness and dizziness.
Herbal teas should not be consumed by pregnant women, lactating mothers or anybody allergic to the ingredients in the teas.
Ginger, dandelion, cinnamon, cardamom and mint tea should be avoided by people with gallstones
Lavender, thyme, cardamom, star anise, clove and basil tea should be avoided by people suffering from gastritis, peptic ulcers or digestive disorders
Cinnamon and clove tea should be avoided by people on anti-coagulants