Yes. Pre-workout heart palpitations can sometimes be linked to ingredients in a supplement, other stimulants, or medicines you are taking. Caffeine is an important example because it can increase heart rate and, particularly at higher amounts or in sensitive people, may cause palpitations. However, palpitations are not automatically caused by your pre-workout. Strenuous exercise itself, lack of sleep, stress, anxiety, nicotine, alcohol, medicines and underlying heart rhythm problems can also be involved.
Heart palpitations can feel as though your heart is racing, pounding, fluttering, skipping beats or beating irregularly. They may last for seconds, minutes or longer. Although palpitations are often harmless, repeated or persistent symptoms should not simply be dismissed as a normal part of training.
If you are trying to work out whether a medicine, supplement or another factor could be contributing, our Symptom-Led Side Effects hub and related parent guide can help you prepare for a discussion with a doctor or pharmacist.
Get urgent medical help if your palpitations do not go away, or if they occur with chest pain, shortness of breath, feeling faint or fainting.
How pre Workout Heart Palpitations can be linked to medicines or supplements
Many pre-workout products are designed to increase alertness, energy or exercise performance. Depending on the formulation, they may contain caffeine or other ingredients with stimulating effects.
Caffeine can make the heart beat faster. The US Food and Drug Administration (FDA) says too much caffeine can cause effects including increased heart rate, heart palpitations, raised blood pressure, anxiety and sleep disturbance. Individual sensitivity varies substantially depending on factors including body weight, medical conditions, medicines and how quickly the body processes caffeine.
The FDA cites 400 mg of caffeine per day for most adults as an amount not generally associated with negative effects, but this is not a personalised safe limit. Some people experience unwanted effects at considerably lower amounts, and caffeine may be coming from more than one source during the day.
For example, your total intake might include:
- a pre-workout supplement;
- coffee or tea;
- energy drinks;
- caffeinated soft drinks;
- another sports or energy product; and
- certain over-the-counter medicines containing caffeine.
The amount listed per serving also matters. If a label gives the caffeine content per scoop but you use more than one scoop, your total intake will be higher.
Pure or highly concentrated caffeine requires particular caution. The FDA warns that highly concentrated caffeine products can cause serious effects, including a rapid or dangerously irregular heartbeat and seizures.
Timing can provide a useful clue, but it cannot prove the cause. Palpitations that repeatedly begin after taking a particular product are worth discussing with a healthcare professional, especially if they are new, becoming more frequent or lasting longer.
Exercise itself also needs to be considered. Strenuous exercise is a recognised trigger for palpitations, which means symptoms during a workout could involve exercise, a supplement, another medicine or several factors occurring together.
Medicines and product categories that may be associated with this symptom
A pre-workout supplement is not the only product that may affect your heartbeat. When discussing palpitations with a doctor or pharmacist, give them a complete list of prescription medicines, pharmacy medicines, supplements, energy products and other stimulants you use.
Categories worth reviewing may include the following.
Caffeine and stimulant-containing products
Caffeine can cause a fast heartbeat and other stimulant effects such as restlessness, tremor, anxiety and difficulty sleeping. Excessive caffeine exposure can cause a rapid or irregular heartbeat.
Do not assume that caffeine from a pre-workout is your only source. Coffee, energy drinks, other supplements and some medicines can add to the total amount consumed.
Decongestants
Some medicines used for blocked noses and cold symptoms have stimulant-like cardiovascular effects. Pseudoephedrine, for example, can raise heart rate and blood pressure, and palpitations are a recognised serious side effect. The NHS also advises limiting caffeine while taking pseudoephedrine because caffeine can increase effects such as shakiness and a fast heartbeat.
Some asthma medicines
The reliever inhaler medicine salbutamol can cause a faster heartbeat, and a fast or irregular heartbeat that does not improve requires medical assessment.
Do not reduce or stop an asthma medicine because you think it is causing palpitations. Poorly controlled asthma can itself be dangerous. Speak to your doctor or pharmacist about the symptoms and how you are using the medicine.
Prescription stimulant medicines
Certain prescription stimulants can affect heart rate. For example, methylphenidate can cause a small increase in heart rate and blood pressure, and fast or irregular heartbeats are a recognised serious side effect.
If you take a prescription stimulant and also use a pre-workout, tell your prescriber or pharmacist about both products. Do not change the prescribed dose or stop the medicine without professional guidance.
You can find broader information about medication side effects in our main medicine safety guide.
Red flags: when this symptom may need urgent medical attention
Palpitations should be assessed urgently when they occur with symptoms that could suggest a more serious heart or circulation problem.
Seek immediate medical help if you currently have palpitations that do not go away, or palpitations accompanied by:
- chest pain;
- shortness of breath;
- feeling faint; or
- fainting.
These are recognised emergency warning signs for heart palpitations.
You should also arrange medical assessment if your palpitations:
- keep coming back;
- are becoming more frequent;
- last longer than a few minutes;
- are new or noticeably different from previous episodes;
- occur when you have an existing heart condition; or
- occur when you have a family history of heart problems.
Do not assume that being young, fit or physically active rules out a medical problem.
If you think you may have taken a very large amount of caffeine or a highly concentrated caffeine product and develop symptoms such as a rapid or irregular heartbeat, breathing difficulty, severe confusion or seizures, seek emergency medical care.
What to track before speaking to a doctor or pharmacist
A clear record of what happened can make it easier for a healthcare professional to assess possible causes.
Write down:
- The exact pre-workout product: Take a photo of the container and ingredient panel if possible.
- How much you used: Record the number of scoops or servings rather than simply saying you took your usual amount.
- Caffeine content: Note the labelled caffeine amount per serving where this information is available.
- When you took it: Record how long before exercising you used the product.
- When the palpitations started: Note whether they started before exercise, during training, immediately afterwards or later.
- How long they lasted: Seconds, several minutes or longer can be useful information.
- What they felt like: Racing, pounding, fluttering, skipped beats or an irregular rhythm.
- Other symptoms: Include dizziness, chest discomfort, breathlessness, nausea, sweating or feeling faint.
- Other caffeine or stimulants: Include coffee, tea, energy drinks and other supplements taken that day.
- Medicines: Include prescription medicines, inhalers, cold and flu remedies, decongestants and pharmacy medicines.
- Other possible triggers: Note unusually strenuous exercise, poor sleep, stress, alcohol or nicotine use.
If you checked your pulse or heart rate at the time, record the result, but do not delay urgent medical care in order to take measurements.
Take the pre-workout container, a photograph of its label, and a list of your medicines and supplements to your doctor or pharmacist. This is often more useful than trying to remember individual ingredients.
What not to do without medical advice
Palpitations can have many possible causes, so avoid trying to diagnose the problem based only on when the symptoms occurred.
In particular:
- Do not change the dose or stop a prescription medicine on your own because you suspect it caused the palpitations.
- Do not take an extra serving of pre-workout because the first serving did not produce the expected training effect.
- Do not deliberately take the suspected product again simply to test whether the palpitations return.
- Do not combine multiple caffeine or stimulant products without checking what they contain.
- Do not ignore recurring symptoms because they only happen during exercise.
- Do not rely on another gym user or online discussion to rule out a medical cause.
Check medicine package leaflets and product labels, and ask a pharmacist to review combinations you are unsure about. A healthcare professional can also decide whether an examination, ECG or other investigation is appropriate. The NHS notes that an ECG may be used when investigating heart palpitations.
Related side-effect guides and reporting options in South Africa
If you are experiencing unexplained symptoms after using a medicine or health product, you can explore the side effect symptoms A-Z or review possible causes in our guide to medicines associated with heart palpitations.
Suspected adverse reactions can also be reported in South Africa. SAHPRA states that both healthcare professionals and consumers can report suspected adverse events and that you do not need to be certain that the product caused the reaction before submitting a report. Consumer reports contribute to medicine and health-product safety monitoring.
See how to report side effects in South Africa if you believe a medicine or relevant health product may have caused an unexpected reaction. Reporting a suspected reaction does not replace medical assessment or emergency treatment.
Is this a common side effect?
Heart palpitations themselves are common and are often not a sign of something serious. Possible triggers include strenuous exercise, caffeine, medicines, stress, lack of sleep, nicotine and alcohol. Whether palpitations are a recognised or common side effect of a particular pre-workout depends on its ingredients and your individual circumstances.
How long can pre-workout heart palpitations last?
Palpitations may last for seconds, minutes or longer. Duration alone does not identify the cause. If episodes keep returning, become more frequent or last longer than a few minutes, arrange medical assessment. Palpitations that do not go away, particularly when accompanied by chest pain, breathlessness or fainting, need urgent medical attention.
Should I stop my medicine if I get heart palpitations?
Do not stop or change a prescribed medicine without speaking to the doctor or other healthcare professional responsible for your treatment. Instead, record what happened and tell them about every medicine, supplement and stimulant product you are using. If symptoms are severe or accompanied by emergency warning signs, seek immediate medical care.
When should I seek help?
Seek urgent medical help if palpitations do not go away or occur with chest pain, shortness of breath, feeling faint or fainting. Arrange a non-emergency medical assessment if the palpitations repeatedly return, are happening more often, last more than a few minutes or concern you.
Pre-workout heart palpitations should not automatically be assumed to be harmless or automatically blamed on one ingredient. Check possible medicine- and supplement-related causes, keep a clear record of your symptoms and products, and speak to a doctor or pharmacist if you are concerned.
This article provides general educational information and is not a diagnosis or substitute for medical advice. If symptoms are severe, worsening or accompanied by chest pain, difficulty breathing, fainting or other concerning symptoms, seek urgent medical help.