Caffeine and ephedrine are the primary ingredients in many popular diet and weight loss pills. Caffeine and ephedrine work individually and together to stimulate your central nervous system. The two ingredients can suppress your appetite, give you energy and increase thermogenesis which helps you burn fat. The combination of caffeine and ephedrine is not without side effects. You should talk to your doctor before using any dietary supplements that contain ephedrine and caffeine.

Increased Blood Pressure

The combination of caffeine and ephedrine can increase your blood pressure. Ephedrine and caffeine stimulate your sympathetic nervous system by increasing neurotransmitters, such as norepinephrine. This stimulant effect can increase your blood pressure by constricting your blood vessels. This is why many diet pill formulas, often called an "ECA stack", contain ephedrine, caffeine and aspirin to thin your blood to offset the blood vessel constriction. If you have a preexisting heart condition or high blood pressure, you should avoid taking diet pills that contain caffeine and ephedrine. Ephedrine and caffeine will not "give" you permanent hypertension, but the combination can increase your blood pressure significantly above your baseline levels temporarily.

Insomnia

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Ephedrine and caffeine can also give you insomnia. If you suffer from insomnia on a regular basis, ephedrine and caffeine will make it even more difficult to go to sleep. High levels of caffeine can make insomnia worse. Combining the two stimulants can make insomnia more likely and worse in many cases. A popular diet pill that contains ephedrine and caffeine can cause restlessness and insomnia. If you are particularly sensitive to caffeine, you should avoid taking supplements that contain caffeine and ephedrine too close to bedtime. Don't consume caffeine four to six hours before bedtime.

Irritability and Anxiety

Both caffeine and ephedrine can cause irritability. Consuming ephedrine can make you two to three times more likely to experience psychiatric symptoms, such as anxiety and irritability. Central nervous system stimulants are often accompanied by a "crash" where you can experience a sudden drop in energy accompanied by anxiety and irritability. If you already take prescription medications for anxiety, irritability or a central system nervous stimulant for attention deficit hyperactivity disorder, such as methylphenidate or dextroamphetamine, you should avoid taking supplements that have ephedrine and caffeine. Compared to other amphetamines, ephedrine produces less euphoria and more anxiety. Likewise, using ephedrine and caffeine on a daily basis can increase the probability of psychiatric side effects.

Long-Term Side Effects and Serious Side Effects

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Although short-term use of ephedrine and caffeine will reduce fatigue, chronic use of the combination and lead to physical dependency. Long-term use can result in exhaustion or chronic fatigue. The combination of caffeine and ephedrine is banned by the International Olympic Committee. An overdose of ephedrine and caffeine can be fatal. The combination is linked to at least 17 deaths.