Pre-workout refers to dietary supplements that people can take before a workout to help maximize their training. Available as premixed drinks, powders, pills, and snack bars, manufacturers formulate these products to boost energy levels and focus. While pre-workout supplements can provide some benefits, they may also cause side effects, such as nausea and heart abnormalities.

To help improve athletic performance, people may consider taking pre-workout supplements. Pre-workout ingredients and their quantities may vary, but they often contain a mixture of ingredients that some evidence suggests may boost energy and focus. Common ingredients might include:

While most of these ingredients are unlikely to cause harm if people follow the correct dosage guidance, individuals may experience some side effects. However, most are likely to be relatively mild and only cause short-term discomfort. People can also take some precautions to try and reduce any potential side effects.

This article explores the possible risks and benefits of pre-workout. It also discusses what to consider when purchasing these supplements.

A person drinking a pre-workout beverage before exercising.Share on Pinterest
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Evidence suggests that for healthy people, consuming pre-workout is generally safe and does not appear to lead to any medical issues. However, some individuals may still experience side effects.

A 2019 study into people who regularly consume pre-workout found that 54% of participants reported side effects, including nausea, skin reactions, and heart abnormalities. However, the research adds that these side effects are likely more common in those who consume more than the recommended serving size.


Caffeine is a popular ingredient in many pre-workouts. The substance prevents adenosine from binding with certain brain receptors, leading to greater nerve activity and making a person feel more alert and energetic. However, consuming caffeine in the late afternoon or evening may lead to sleep problems for some individuals, particularly those who metabolize caffeine slowly.

Too much caffeine may also cause people to experience anxiety, a faster heart rate, and headaches. As a result, it is not advisable for those sensitive to caffeine to consume pre-workout containing this ingredient.

Pre-workout supplements can also contain several ingredients that may cause gastrointestinal distress. Caffeine may cause stomach upset by increasing the release of stomach acid, which may result in acid reflux. Although less common than caffeine, some pre-workout may contain sodium bicarbonate, which can cause bloating, nausea, and abdominal pain. However, evidence suggests that this is not particularly common.


Some pre-workouts contain niacin, also known as vitamin B3. Consuming it can lead to small blood vessel dilation, which may cause flushing of the skin, normally on a person’s face, chest, or arms.


Beta-alanine is an amino acid that may cause paraesthesia, a tingling sensation that people commonly feel in the face, neck, and back of the hands. However, this neurological effect is unlikely to be harmful and normally stops 60–90 minutes after consumption.


Creatine may cause water retention and bloating. This occurs because creatine carries water into the muscles, and sometimes the body cannot absorb all the extra water. However, studies suggest this only occurs over the first few days of consuming creatine and is unlikely to continue long term.

A 2018 study focusing on the effects of multi-ingredient pre-workout supplements (MIPS) on recreationally active females noticed that MIPS did not significantly raise heart rate and systolic blood pressure but did raise diastolic blood pressure in participants.

Diastolic blood pressure measures the pressure in a person’s arteries between heartbeats. Although findings suggest consuming MIPs is generally safe, those with conditions that may lead to higher diastolic blood pressure may wish to be cautious when consuming such products.

Pre-workouts are often a blend of many different ingredients that researchers have investigated for their potential athletic performance benefits.

Creatine is one such popular and heavily-researched supplement for athletic performance. The International Society of Sports Nutrition (ISSN) states the substance is the most effective nutritional supplement for increasing performance in high-intensity exercise and gaining lean body mass. ISSN research suggests creatine may also enhance recovery after a workout, reduce muscle damage, and potentially help rehabilitation after injury.

Many people may attribute some benefits of pre-workout supplements to caffeine. It can help improve focus and alertness, and it works quickly, peaking in the bloodstream within 60 minutes. A 2018 review looking at the athletic benefits of caffeine consumption concluded that it may significantly benefit muscle strength and power. The research also stated that caffeine’s most noticeable athletic effect is improving upper body strength.

Other common ingredients in MIPs may also have potential benefits. Another ISSN study found beta-alanine supplementation had links with endurance and strength benefits in doses of 4–6 grams per day.

While several common ingredients on their own may provide some athletic benefit, recent research focuses on the effects of combined ingredients within pre-workout supplements. A 2018 paper concluded that although further research is necessary, consuming MIPs can improve athletic performance and increase strength and endurance.

Some pre-workouts may list ingredients as a “proprietary blend” and not state the exact amounts. People interested in taking pre-workouts may wish to find products that list exact amounts, as well as ones that feature verification from a trusted source, to avoid consuming an unhealthy amount of a certain ingredient.

Some ingredients in pre-workout supplements may also interact with certain medications. Before taking them, seek advice from a medical professional to fully understand how their pre-workout may affect their medication.

Many pre-workouts also contain caffeine, which some people may have difficulting tolerating. Everyone metabolizes caffeine at a different rate, and some may be more sensitive to its effects. Those who are more caffeine sensitive, even in lower doses, may experience symptoms such as nausea, anxiety and jitteriness, and insomnia.

Additionally, people with health conditions, such as diabetes, insomnia, anxiety, or heart conditions, may wish to consider how the ingredients of pre-workouts may affect them and seek medical advice before taking these products.

People can reduce the potential side effects of pre-workouts by following the recommended dosage on the product label or packaging.

Research into consumer habits around pre-workout supplements found that 14% of people reported consuming two or more doses, while 18% of individuals consumed them more than once a day. To reduce some side effects, people can either lower the dose or split the dose into several smaller amounts.

If a person is experiencing digestive issues when starting a pre-workout, they may wish to find a product that does not include potential triggers, such as caffeine and sodium bicarbonate. They could also try lowering the dosage.

To avoid potential sleep problems, a person can take pre-workouts, including caffeine earlier in the day, to ensure the stimulant has worn off before going to bed.

If an individual wants to avoid pre-workouts altogether, they can find common ingredients, including creatine and beta-alanine, in foods such as red meat, fish, and poultry. A person may also improve their workout without pre-workout supplements by focusing on their diet before and after exercising. Health experts suggest:

  • eating a meal within 2 hours of a workout
  • eating snacks beforehand that include complex carbohydrates and protein
  • staying hydrated before and throughout a workout
  • eating a balanced meal after a workout, preferably including protein

While it is unnecessary to consume pre-workout supplements to improve athletic performance, some evidence suggests they may provide some benefits, including increased strength, endurance, and focus. However, some people may be sensitive to certain ingredients in pre-workout and experience some side effects, including nausea, headaches, and jitters.

To try and reduce potential side effects, individuals should take no more than the recommended dosage and consider a lower dosage. It may also be advisable to avoid certain ingredients.

People with pre-existing medical conditions, those who take medications, or those experiencing side effects from pre-workout should seek advice from a medical professional to find the right supplement for them.