Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, Ineffective, and Insufficient Evidence to Rate. The effectiveness ratings for GUARANA are as follows:
Insufficient evidence to rate effectiveness for…
- Anxiety. Early research shows that taking a product containing hawthorn, black horehound, passionflower, valerian, cola nut, and guarana can reduce anxiety in some people. It is not clear if guarana alone is beneficial.
- Lack of appetite in people with cancer. Early research shows that taking guarana extract slightly improves appetite and prevents weight loss in people with cancer who have lost their appetite and are losing weight. But the benefit is very small.
- Tiredness in people treated with cancer drugs. Some research shows that taking it can reduce feelings of tiredness in some people undergoing chemotherapy. But conflicting results exist.
- Improving memory and thinking skills (cognitive function). Early research in healthy people shows that taking a single dose of extract can improve thinking speed and some aspects of memory. However, other research shows that taking guarana does not improve mental function in adults or older people.
- Athletic performance. Research shows that taking a single dose of a product containing guarana, B vitamins, vitamin C, and minerals improves exercise tolerance in trained athletes by a very small amount. It is not clear if it alone is beneficial.
- Obesity. Taking guarana along with mate and damiana seems to increase weight loss. There is also developing evidence that taking a specific combination product containing guarana, ephedra, and 17 other vitamins, minerals, and supplements helps reduce weight by approximately 2.7 kg over 8 weeks when used with a low-fat diet and exercise. It is not clear if guarana alone is beneficial.
- Feelings of well-being. Early research shows that taking it does not improve feelings of well-being in healthy individuals.
- A serious illness caused by radiation exposure. Research shows that taking guarana does not improve symptoms of depression or tiredness in people undergoing radiation treatment.
- Athletic performance.
- Chronic fatigue syndrome (CFS).
- Fluid retention.
- Heart disease.
- Increasing sexual desire in healthy people.
- Low blood pressure.
- Menstrual cramps (dysmenorrhea).
- Rheumatoid arthritis (RA).
- Other conditions.
More evidence is needed to rate the effectiveness for these uses.
Side Effects Of Guarana
When taken by mouth: Guarana is LIKELY SAFE for most adults when taken in amounts commonly found in foods. When taken by mouth in medicinal amounts for a short time, guarana is POSSIBLY SAFE.
When taken by mouth in high doses for a long time, it is POSSIBLY UNSAFE. Guarana contains caffeine. Doses containing more than 400 mg of caffeine daily have been linked to side effects. Side effects depend on the dose. At typical doses, the caffeine can cause insomnia, nervousness and restlessness, stomach irritation, nausea, vomiting, increased heart rate and blood pressure, rapid breathing, tremors, delirium, diuresis, and other side effects. Large doses might cause headache, anxiety, agitation, ringing in the ears, pain when urinating, stomach cramps, and irregular heartbeats. People who take guarana regularly may experience caffeine withdrawal symptoms if they reduce their usual dose.
When taken by mouth or injected in very high doses, guarana is LIKELY UNSAFE and even deadly, due to its caffeine content. The fatal dose of caffeine is estimated to be 10-14 grams. Serious poisoning can also occur at lower doses, depending on an individual’s caffeine sensitivity or smoking behavior, age, and prior caffeine use.
Warnings & Precautions
- Pregnancy and breast-feeding: Guarana is POSSIBLY SAFE for pregnant and breastfeeding women when taken in amounts commonly found in foods. If you are pregnant or breast-feeding, guarana should be taken with caution due to the caffeine content. Small amounts are probably not harmful. However, taking guarana in high doses by mouth is POSSIBLY UNSAFE. Consuming more than 300 mg of caffeine daily has been linked to an increased risk of miscarriage and other negative effects.
- In women who are nursing, caffeine passes into breast milk and can affect a nursing infant. 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 problems, irritability, and increased bowel activity in breast-fed infants.
- Anxiety: The caffeine in guarana might make feelings of anxiety worse.
- Bleeding disorders: There is some evidence suggesting that the caffeine in guarana might make bleeding disorders worse, although this has not been reported in people. If you have a bleeding disorder, check with your healthcare provider before starting guarana.
- Diabetes: Some research suggests that the caffeine in guarana may affect the way people with diabetes process sugar (glucose) and may complicate blood sugar control. There is also some interesting research that suggests caffeine may enhance the warning symptoms of low blood sugar in patients with type 1 diabetes. Some studies show that the symptoms of low blood sugar are more intense when they start in the absence of caffeine, but as low blood sugar continues, symptoms are greater with caffeine. This might increase the ability of diabetic patients to detect and treat low blood sugar. However, the downside is that caffeine might actually increase the number of low-sugar episodes. If you have diabetes, talk with your healthcare provider before starting guarana.
- Diarrhea. Guarana contains caffeine. The caffeine, especially when taken in large amounts, can worsen diarrhea.
- Seizures. Guarana contains caffeine. The caffeine in guarana might increase the risk of seizures and reduce the benefits of many medications used to control seizures. If you have seizures, talk to your healthcare provider before using guarana.
- Irritable bowel syndrome (IBS): Guarana contains caffeine. The caffeine in guarana, especially when taken in large amounts, can worsen diarrhea and might worsen diarrhea some people have with IBS.
- Heart disease: The caffeine might cause irregular heartbeat in certain people. Use with caution.
- High blood pressure: Taking guarana might raise blood pressure, in people with high blood pressure due to its caffeine content. However, this effect might be less in people who are regular coffee-drinkers or otherwise use caffeine on a regular basis.
- Glaucoma: The caffeine in guarana increases the pressure inside the eye. The increase occurs within 30 minutes and lasts for at least 90 minutes after drinking caffeinated beverages.
- Bladder control problems (Incontinence): Guarana contains caffeine. The caffeine in guarana might reduce bladder control, especially in older women. If you need to urinate often with high urgency, use guarana cautiously.
- Osteoporosis: The caffeine in guarana can flush the calcium out of the body through the kidneys. This calcium loss might weaken bones. If you have osteoporosis, don’t consume more than 300 mg of caffeine per day. Taking calcium supplements may also help to replace any lost calcium. If you are generally healthy and getting enough calcium from your food or supplements, taking up to 400 mg of caffeine per day doesn’t seem to increase the risk of getting osteoporosis.
- Schizophrenia: Guarana contains caffeine. The caffeine in guarana might make some symptoms of schizophrenia worse. If you have schizophrenia, use guarana cautiously.
Dosage Of Guarana
The appropriate dose of guarana depends on several factors such as the user’s age, health, and several other conditions. At this time there is not enough scientific information to determine an appropriate range of doses for guarana. Keep in mind that natural products are not always necessarily safe and dosages can be important. Be sure to follow relevant directions on product labels and consult your pharmacist or physician or other healthcare professional before using.
Consult your doctor or pharmacist.
All information has been provided courtesy of MedLinePlus from the National Library of Medicine and from the FDA.