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Side Effects of Xenadrine EFX

author image Sharon Perkins
A registered nurse with more than 25 years of experience in oncology, labor/delivery, neonatal intensive care, infertility and ophthalmology, Sharon Perkins has also coauthored and edited numerous health books for the Wiley "Dummies" series. Perkins also has extensive experience working in home health with medically fragile pediatric patients.
Side Effects of Xenadrine EFX
Taking stimulants such as Xenadrine EFX may have serious side effects.

Xenadrine EFX, a popular weight-loss supplement, contains ingredients that can cause side effects. The supplement does not contain ephedra, which has been banned from over-the-counter supplements because of its dangerous side effects. The supplement does contain l-tyrosine, green tea, bitter orange, yerba mate, and grape leaf extract and seropro in three “proprietary blends” that don’t list the specific amounts of any one ingredient. When the ingredients in this supplement are combined, the potential side effects may be worsened.

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Increased Heart Rate

A study conducted by University of California scientists found that Xenadrine EFX increased the heart rate by 11 to 16 beats per minute, or bpm. This is an 18 percent increase for people whose heart rate is normally 80 bpm. Since this supplement contains three sources of caffeine -- green tea, cocoa and yerba mate -- and since caffeine is known to increase your heart rate, this is not a surprising finding. The University of California states the product contains as much caffeine as 3 cups of coffee. Bitter orange, another ingredient found in the supplement, contains synephrine and octopamine. These two chemicals behave similarly to ephedra and also increase the heart rate, according to Mayo Clinic nutritionist Katherine Zeratsky, R.D., L.D. Chest pain or signs of a stroke, such as blurred vision or one-sided weakness, should receive immediate medical evaluation.

Increased Blood Pressure

Xenadrine EFX may also raise blood pressure by 7 to 12 percent, the University of California study found. Bitter orange is one of the ingredients that can raise blood pressure. Caffeine can raise blood pressure by increasing the heart’s output as well as increasing the amount of blood ejected with each beat. Caffeine may also cause temporary stiffness of the aorta, the largest artery in the body. The effects of bitter orange and caffeine together may be intensified, Zeratsky warns. If you have high blood pressure, do not take this product without your doctor's supervision.


Xenadrine EFX can cause irritability, anxiety, restlessness, jumpiness and sleep disorders. The University of California researchers found that the product increased alertness.

Ischemic Colitis

Bitter orange can cause ischemic colitis, which involves a decrease in blood flow to the intestine characterized by severe diarrhea, bloody stools, vomiting, abdominal pain or fever. These signs and symptoms require prompt medical evaluation.

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