15 Harmful Effects Of Tea And Coffeine

More than 4 cups of coffee linked to early death.
 A Mayo Clinic partnered study found that men who drank more than four 8 fl.oz. cups of coffee had a 21% increase in all-cause mortality. However, those that reported that they consumed excessive amounts of caffeine were also likely to smoke and have poor fitness. Dr. Nancy Snyderman from NBC said there were a few discrepancies with the study, but stresses that moderation is still key. 
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Caffeine can cause headaches.
 While occasional doses of caffeine can relieve headache symptoms, the overuse of caffeine can cause headaches and lead to migraines. 
Caffeine could reduce fertility in women. 
A study from The University of Nevada School of Medicine showed that caffeine can reduce a woman’s chances of becoming pregnant by about 27%. 
Caffeine may not be healthy for type 2 diabetics. A study conducted by the American Diabetes Association showed that caffeine impaired glucose metabolism in those with type  diabetes. 
Caffeine Overdose. While overdose is rare, it can lead to many adverse symptoms including death, especially in those with underlying medical conditions. Some have a lower tolerance for caffeine than others. 

Caffeine Allergies.
 Some people have over-sensitivity to the caffeine molecule, which causes allergic-like reactions in the body such as hives and pain. Although not a true allergy, many report very negative symptoms after consuming even the smallest amounts. 

Caffeine causes more forceful heart contractions.
 A recent study showed that immediately after energy drink consumption the heart produced more forceful contractions. It is unclear if this has any long-term health implications except for those with known health conditions. 

Worse Menopause Symptoms.
 A recent study published in The Journal of The North American Menopause Society showed that menopausal women who consumed caffeine had a greater degree of vasomotor symptoms.
Caffeine consumption can lead to increased anxiety, depression and the need for anxiety medication. 
Caffeine increases the amount of sugary beverages consumed by people, which contributes to obesity and diabates.

Caffeine consumption may raise blood pressure in those already suffering from hypertension. People with hypertension were given 250mg of caffeine (about 2 coffees) and the data revealed that their blood pressure was elevated for about 2-3 hours after the caffeine. 
Caffeine linked to gout attacks. This study showed that people who binge on caffeinated beverages increase their risk for a gout flare-up

Caffeine could cause incontinence.
A study out of the University of Alabama showed that women who consume a lot of caffeine are 70% more likely to develop incontinence. 

Caffeine may cause insomnia.
 Caffeine in a person’s system at bedtime can mimic the symptoms of insomnia. Src.
Caffeine can cause indigestion. People who consume caffeinated beverages often report an upset stomach or indigestion. This mainly occurs when the beverages are consumed on an empty stomach.