Zantrex, or Zantrex-3 as it is commonly called, is an over-the-counter weight loss supplement manufactured by Zoller Laboratories. According to Zoller Laboratories, each 2-capsule serving contains more than 300 mg of caffeine, so people who are highly sensitive to caffeine and those who have high blood pressure, diabetes or heart conditions should not take Zantrex. Due to the high caffeine content there are several potentially dangerous side effects associated with Zantrex. As with any diet supplement, it is always advisable to consult a doctor before use.
Because caffeine is a stimulant, many people will experience anxiety, irritability, nervousness, tremors and/or profuse sweating when consuming large doses of the drug. Zoller Laboratories suggests taking two capsules before each meal, up to six capsules a day. One two-capsule dose of Zantrex contains more caffeine than the 200 to 300 mg per day the Mayo Clinic recommends as a general maximum, so anxiety and nervousness may be quite profound, especially in individuals who already consume caffeinated beverages or foods on a regular basis. Anxiety and its associated physical effects may lead to more severe mental issues and may intensify with continued caffeine usage.
The caffeine in Zantrex may lead to gastrointestinal problems such as nausea, vomiting, diarrhea or stomachaches. These side effects are more prevalent in individuals starting Zantrex who do not regularly consume caffeine, and thus do not have a tolerance to the drug. Many gastrointestinal side effects may subside on their own, but do not ignore persisting symptoms. Prolonged vomiting or diarrhea can cause moderate to severe dehydration that may lead to other medical problems. Seek medical attention as soon as possible if blood is present in vomit or stools, as this can be a sign of dangerous internal bleeding or a severe gastrointestinal problem.
Large doses of caffeine, such as those in Zantrex, can cause fast or irregular heartbeat. Any amount of caffeine will slightly increase a person's heart rate, but massive doses of the drug over a long period of time may contribute to further heart problems. People taking Zantrex should avoid caffeinated beverages and foods as much as possible due to the increased risk of cardiovascular problems associated with long-term irregular heart rhythms.
Caffeine causes sleep disturbances such as insomnia or unusual tiredness in many individuals. While these two side effects may seem contradictory, one of the biggest sleep-related dangers of Zantrex's high caffeine content is the inability to focus and concentrate while driving or operating dangerous equipment. Caffeine causes many people to feel extremely tired, but they often find they are unable to fall asleep or stay asleep for long periods of time. Lack of sleep can create a potentially dangerous situation when an individual's concentration is negatively affected, and the immune system can also be compromised by not getting enough quality sleep.
Some medications and supplements can negatively interact with caffeine and should not be taken in conjunction with Zantrex. Antibacterial antibiotics, such as ciprofloxacin and norfloxacin, can inhibit the body's ability to break down caffeine. This increases the amount of time caffeine stays in an individual's system and can increase the possibility of an overdose. Theophylline and other bronchodilators have many caffeine-like effects. Taking Zantrex while on these types of medications greatly increases the risk of negative gastrointestinal and cardiovascular effects. The Food and Drug Administration has banned the use of ephedra in supplements because of the increased risk of stroke, seizure, heart attack or death. Some herbal teas still contain ephedra, and it is especially dangerous when used in conjunction with caffeine-containing drugs such as Zantrex.