Are Energy Drinks Bad?

Energy drinks are typically classified as functional beverages with stimulating effects. Depending on the ingredients, energy drinks are generally designed to boost energy and improve cognitive function while reducing fatigue. Some drinks may also claim to enhance metabolism, physical endurance, and recovery from stress or training.

The energy drinks market has grown substantially in recent years, and product ingredients now vary widely. However, most beverages are around 8-16 fl oz (240-480 mL) and may contain caffeine, B vitamins, electrolytes, minerals, and/or herbal extracts, botanicals, or other nootropic ingredients.¹

The most common ingredient in energy drinks is caffeine, which provides the ‘energy boost’, but may also have side effects when consumed in excess. 

Other ingredients such as sugar and herbal extracts may have benefits for energy and focus as well as side effects.

Caffeine is a central nervous system stimulant and the most widely consumed psychoactive drug in the world.² The caffeine content of most energy drinks can range from around 50–500 mg per can or bottle. A standard 250 mL can could contain around 80 mg, while a 500 mL can may contain around 160 mg.

Caffeine blocks adenosine receptors, causing neurons to fire more rapidly. This increases glutamate (an excitatory messenger) and dopamine (a “motivation/drive” messenger). The result is increased alertness, focus, and responsiveness. At the same time, inhibition of adenosine increases heart rate, which facilitates faster reaction time, greater vigilance and reduced sense of fatigue.³

Short-term effects include increased blood pressure and heart rate, and higher epinephrine and norepinephrine. High consumption can lead to anxiety and feeling ‘wired’ or jittery. Regular consumption in high amounts can lead to sleeplessness and anxiety, seizures, dysrhythmias, and tachypnea (rapid breathing).⁴

In pregnant women, caffeine is associated with a higher risk of miscarriage and lower birth weight.⁵

Caffeine increases gastric acid secretion and relaxes the esophageal sphincter, increasing risk of dyspepsia and reflux. It is a diuretic and also stimulates colonic motility, which can lead to diarrhea and abdominal cramping.

Taurine is a naturally occurring sulfonic acid in heart and skeletal muscle involved in membrane stabilization and neuromodulation. It is used to enhance the performance effects of caffeine, supporting endurance and energy. Studies suggest that taurine may improve cardiac fitness and vascular health.
Excessive consumption of taurine supplements may lead to gastrointestinal issues (such as nausea, vomiting, and diarrhea) and neurological symptoms (dizziness, tremors, and headache).⁶

A 2025 study found that prolonged taurine supplementation promoted hepatic steatosis and inflammation, along with dysregulated bile acid and gastrointestinal issues.⁷

Guarana seeds are higher in caffeine than coffee beans and also contain theobromine (which boosts energy) and theophylline (which relaxes muscles). High doses can cause tremor, jitteriness, agitation, confusion, hypertension and dehydration.⁸

Panax ginseng, yerba mate, green tea, and ginkgo biloba are known for their benefits in stimulating the nervous system and supporting cognitive function. 

Many energy drinks contain sugars which provide energy in the form of glucose, which delivers a quick hit of energy before or during physical activity. Glucose with caffeine is also shown to enhance cognitive performance.⁹

High sugar intake increases risk of hyperglycemia, hyperinsulinemia, and increased triglycerides, which have been linked to obesity, insulin resistance, type 2 diabetes and cardiovascular disease.¹⁰

Some data suggests that sugar-free formulations now make up around a third of the energy drink market today.¹¹ They have no benefits for energy production but provide a sweet taste without additional calories.

Common sweeteners include sucralose, acesulfame potassium (Ace-K), aspartame, and plant-based sweeteners such as erythritol and stevia.

High consumption of these sweeteners is linked to an increased risk of metabolic health conditions and cardiovascular disease, including stroke, coronary heart disease, and mortality.
Aspartame is associated with neurotoxicity and cancer, while other sweeteners are known to cause microbiome dysbiosis and inflammation in the gut, as well as impaired glucose metabolism.¹²

People most strongly advised to avoid energy drinks include:

• Children under 12 and adolescents aged 12-18. The stimulating effects of energy drink formulas (mainly caffeine) can cause increased heart rate, high blood pressure, headaches, anxiety, vomiting, and diarrhea. Research has shown that high intake of energy drinks in these age groups is associated with adverse effects on the cardiovascular system, neuropsychological system, and other organs.¹³
  
  
• People with preexisting health conditions such as cardiovascular disease, kidney or liver disorders, diabetes, mood or behavioral disorders, hyperthyroidism, or those taking certain medicines.
  
  
• Women who are pregnant or breastfeeding.
  
  
• Anyone already consuming high amounts of caffeine or taking stimulant medications.

Pre-workout energy drinks are marketed to improve exercise performance, stamina, and/or recovery. They usually contain combinations of carbohydrates, caffeine, amino acids, creatine, beta-alanine, and vasodilators (such as nitrates, L-citrulline, and L-arginine).

The International Society of Sports Nutrition (ISSN) has stated that pre-workout drinks primarily containing caffeine, beta-alanine, and nitrates can improve acute exercise performance, cognitive function, and/or training adaptations.

Caffeine has consistently been shown to improve exercise performance in doses of 3-6 mg/kg body mass, but very high doses (e.g., 9 mg/kg) are associated with a high incidence of side effects.¹⁴ While creatine, nitrates, or beta-alanine may also contribute to exercise performance, caffeine appears to provide most of the benefits, and high consumption can result in the same adverse effects as other energy drinks: higher heart rate and blood pressure, jitteriness, anxiety, and stomach upset.¹⁵

Many energy drinks fortified with B vitamins use folic acid, the synthetic form of folate (vitamin B9). These may not be suitable for people with the MTHFR genetic mutation due to a reduced ability to process folic acid, which can lead to an accumulation of unmetabolized folic acid (UMFA). UMFA is associated with vitamin B12 deficiency, cognitive degeneration, and mood disorders such as depression.¹⁶ Excess folic acid in the blood can also ‘mask’ B12 deficiency, potentially leading to severe cognitive impairments if not detected.
A 2023 meta-analysis reported that caffeine intake may increase serum homocysteine levels, which can be problematic for those with MTHFR variants.¹⁷ High homocysteine is common in those with MTHFR variants due to impaired metabolism of homocysteine to methionine, so the additional burden from caffeine could pose further risk.

Some energy drinks are now made with methylated (active) nutrients, usually methylcobalamin. Vitamin B12 plays a major role in converting carbohydrates into glucose required for energy, as well as red blood cell formation and cognitive function.

Note: Although unlikely, some people who are sensitive to methylated nutrients may experience overstimulation when consuming both methylated energy drinks and methylated supplements. If you are concerned, talk to your healthcare practitioner.

The safest energy drinks are those that are not processed or packaged. 

Naturally brewed teas such as green tea or matcha provide caffeine in lower concentrations than most energy drinks, along with the highly beneficial antioxidant epigallocatechin gallate (EGCG). Yerba mate supports healthy metabolic function with both caffeine and theobromine.

Nutritional beverages that contain active forms of B vitamins and other nutrients may also be beneficial. Active or methylated nutrients are immediately available for use in the body, unlike synthetic nutrients such as folic acid. Check the nutritional information carefully for ingredients such as methylfolate (vitamin B9) and methylcobalamin (B12).