Stimulant-induced arrhythmia: heart rhythm problems after stimulant drugs

An arrhythmia is an abnormal heart rhythm: the heart beats too fast, too slow or irregularly. The British Heart Foundation lists arrhythmia among the heart conditions that can cause palpitations, alongside cardiomyopathy, congenital heart conditions, heart attack, heart failure and heart valve disease.

Stimulant drugs act on the nervous system in a way that speeds up the heart and raises blood pressure. FRANK describes cocaine as making your heart beat faster, and the NHS lists recreational drugs among causes of palpitations. The term stimulant-induced arrhythmia is used when an abnormal rhythm is triggered by such a drug, for example with cocaine or amphetamine.

Most palpitations are harmless. The NHS says heart palpitations are common and not usually a sign of anything serious, and the British Heart Foundation says that in most cases they are harmless. The concern with stimulant drugs is that they can both cause an unpleasant fast heartbeat and, in some people, a dangerous rhythm.

The NHS says heart palpitations are when your heartbeat becomes more noticeable, feeling uncomfortable or unusual. The sensations it describes are listed below, and the British Heart Foundation gives a similar description. Palpitations can last seconds, minutes or longer, and you may feel them in the chest, neck or throat.

• A heartbeat that feels like it is racing or beating very fast.

• A heartbeat that feels irregular, with skipped or extra beats.

• Pounding or thumping in the chest, neck or throat.

• Fluttering.

• Associated symptoms such as chest pain, shortness of breath, dizziness or fainting, which are warning signs.

The NHS says to call 999 or go to A&E if you currently have heart palpitations and they do not go away, or you also have chest pain, shortness of breath or feel faint or have fainted. The British Heart Foundation says to call 999 if you have palpitations with severe shortness of breath, chest pain or tightness, dizziness and light-headedness, or fainting and blackouts. The NHS advises not to drive yourself to A&E but to ask someone to drive you or call 999 for an ambulance, and to bring any medicines you take.

If you have had these symptoms but they have now stopped, the NHS advises asking your GP surgery for an urgent appointment, calling 111 or getting help from 111 online.

Tell the ambulance crew and hospital staff what you have taken, because it is relevant to your care. FRANK says even healthy young people can have a heart attack or stroke after using cocaine, so a person with chest pain after stimulant use should be treated as an emergency.

FRANK describes the cardiovascular risks of the two stimulants it covers most clearly. On cocaine, it says that effects include a faster heart rate, that cocaine is risky for anyone with high blood pressure or a heart condition, and that anyone can have a panic attack, heart attack or stroke if they take too much. It adds that the risk of overdose increases if cocaine is mixed with other drugs or alcohol.

On speed, FRANK says it puts a strain on the heart so it is definitely not advisable for people with high blood pressure or a heart condition, that users have died from taking too much, and that there is a risk when using a range of stimulant drugs at the same time. It also says speed is usually very impure, so what ends up in the bloodstream is not only amphetamine, and that injecting is particularly dangerous.

The British Heart Foundation lists other triggers of palpitations that can add to the effect: alcohol, caffeine, certain medicines (both prescription and over-the-counter), intense exercise, smoking or vaping, and stress, anxiety or panic attacks. Combining these with stimulant drugs is a common way for a rhythm disturbance to start.

Underlying conditions raise the concern. The NHS notes that a heart rhythm problem or other heart problems such as heart valve disease, iron deficiency anaemia or an overactive thyroid can cause palpitations, so a person with a stimulant-triggered episode may also have an unrecognised heart or thyroid problem that needs to be looked for.

The NHS says you may have an electrocardiogram (ECG) to help find out what the cause might be, a test where small pads are stuck to your skin to check the electrical signals from your heart, and you may need to be referred to a cardiologist for tests and treatment. The British Heart Foundation says your GP may arrange an ECG to check whether the heart rate is regular and at a normal rate, and that if the ECG shows something abnormal or symptoms continue, further tests or heart monitoring over a longer period may be needed.

The NHS says treatment for palpitations depends on the cause, that they often do not need to be treated, and that if palpitations are caused by a heart problem you may need medicines or a procedure to help control your heartbeat. For drug-related episodes, the key step is avoiding the stimulant. The NHS says avoiding triggers such as stress, smoking, caffeine and alcohol can help if palpitations are not caused by a health condition, and the British Heart Foundation gives the same advice, including limiting alcohol to no more than 14 units a week.

If you use stimulants and are worried about your heart, speak to your GP or an NHS drug and alcohol service. The NHS has a page on getting help for drug addiction, and FRANK provides information about drugs. The NHS says a GP may be a good place to start, can discuss your problems with you and help get you into treatment, and will usually refer you to a local drug service; you can also approach your local drug treatment service yourself.

Many episodes settle once the drug wears off, but severe ones can be life threatening. FRANK says users have died from taking too much speed and that cocaine can cause a heart attack or stroke even in healthy young people, so there is no reliably safe level.

The most effective way to reduce risk is not to use stimulants. If you do, the sources advise against mixing stimulants with each other, with other drugs or with alcohol, and say that people with high blood pressure or a heart condition should avoid them. Keep a diary of symptoms and triggers if you have recurring palpitations, as the British Heart Foundation suggests, and tell your GP about all substances you use so that the right tests can be arranged.

The NHS says that medicines are among the common causes of palpitations and advises checking the leaflet that comes with the medicine; if you notice palpitations on a prescribed medicine, speak to your prescriber rather than stopping it yourself.