Quick answer
Long QT syndrome is an electrical heart condition that can cause fainting, seizures and, in some cases, sudden cardiac arrest — and certain common medicines can make it worse, including some antibiotics, antidepressants, antipsychotics and anti-nausea medicines. healthdirect advises telling every doctor you have long QT before they prescribe. A long QT syndrome medical ID tells them when you cannot, and tells a bystander that a collapse means CPR and a defibrillator, now.
Long QT syndrome often hides in plain sight. People with it can look and feel perfectly well, play sport and live full lives — the Better Health Channel notes about one third of people with the condition have no symptoms at all. The risk shows itself in moments: a faint during a race, a collapse when an alarm goes off, or a new prescription that nobody checked. This guide explains what long QT is, what triggers events, which kinds of medicines to question, and what your medical ID should say.
What long QT syndrome is
According to healthdirect, long QT syndrome (LQTS) is a disorder of the heart’s electrical system that can cause episodes of fast, disordered heartbeats called arrhythmias. It is named after the pattern it shows on an electrocardiogram (ECG). People with LQTS may have fast or irregular heartbeats, fainting or seizures, and if the heart beats irregularly for long enough it can cause cardiac arrest and possibly sudden death.
LQTS is usually genetic and present from birth, though it may only be diagnosed in childhood, young adulthood or later. It can also be acquired, caused by certain medicines. The Better Health Channel describes it as a relatively common cause of sudden death in children and young adults.
Warning signs worth taking seriously
The Better Health Channel and healthdirect both advise getting checked for long QT if:
- you faint for no apparent reason
- you faint during or shortly after exercise or emotional excitement
- there is a family history of unexplained fainting or sudden death
- there is a family history of long QT syndrome
Fainting has many harmless causes, which we cover in our fainting first aid guide. The point is that a faint in someone known to have long QT is not the same event, and the people around them need to know that.
What can trigger an event
The Better Health Channel lists event triggers for long QT syndrome, including:
| Trigger | Examples |
|---|---|
| Exercise | Sport and intense physical activity |
| Being startled | A loud noise such as a car horn, a ringing phone or an alarm clock |
| Stress | Exams, tests and other stressful situations |
| Strong emotion | Anger or crying |
healthdirect notes treatment may involve limiting intense physical activity; your cardiologist will tell you what is safe for you. If you exercise, our guide to medical ID for runners, cyclists and exercise covers wearing an ID while training.
Medicines to question
This is where a medical ID earns its keep. healthdirect explains that if you have the gene for LQTS, some medicines can increase your risk of an abnormal fast heart rhythm, and that if you have been diagnosed you need to avoid medicines that increase that risk. Its advice: “Tell your doctors you have LQTS before they prescribe a medicine, and check with your pharmacist before you take a new medicine.”
The Better Health Channel lists the kinds of medicines — both prescribed and over-the-counter — that can prolong the QT interval, including some:
- antiarrhythmic medicines (used to control heart rhythm)
- antibiotics
- antidepressants
- antipsychotics
- anti-nausea medicines
- diuretics
Why this matters in an emergency
Anti-nausea medicine in an ambulance, an antibiotic in an emergency department, an antipsychotic or antidepressant on a ward: each is routine, each belongs to a group on that list, and each is usually given by someone who has never met you. “LONG QT — CHECK QT-PROLONGING DRUGS” gives them the question to ask. Your cardiologist can tell you which specific medicines to avoid.
If someone with long QT collapses
Unresponsive and not breathing normally
Call Triple Zero (000), start CPR, and send someone for the nearest defibrillator. Follow the steps in our guides to CPR and using a defibrillator.
Some people with long QT have an implantable cardioverter defibrillator (ICD), which healthdirect notes may be needed, and which the Better Health Channel says is used when beta blockers are not enough. An ICD in the chest belongs on your medical ID and in your record; see what counts as a medical implant or device.
Who reads a long QT medical ID
Australian resuscitation guidance tells responders to look. ANZCOR Guideline 2 includes, in the initial assessment of an emergency, checking for “physical (eg. alert jewellery) or electronic alert devices (eg. smartphone application) that may be relevant to assessment or management”. For long QT, the readers are:
- A coach, teacher or bystander who needs to know a faint may be a heart rhythm problem.
- The paramedic choosing anti-nausea medicine or sedation.
- Any doctor or pharmacist about to prescribe or dispense something new.
What a long QT syndrome medical ID should say
On the band
- LONG QT SYNDROME (and ICD if you have one)
- CHECK QT-PROLONGING DRUGS
- Your membership number, so the rest can be read
In the profile
- Your diagnosis, type if known, and your usual ECG findings as your cardiologist describes them.
- Your medicines, such as a beta blocker, with dose and timing.
- Any ICD or pacemaker: manufacturer, model and the clinic that manages it.
- A list of medicines your cardiologist has told you to avoid.
- Your known triggers and any activity limits.
- Your cardiologist, hospital and GP, and which family members have been tested.
- Emergency contacts.
Long QT, your medicines, your ICD — readable before the next prescription.
A MedibandPlus profile stores your long QT diagnosis, medicines to avoid, device details and contacts behind a membership number on a band you wear. No app, no login, from $19 a year.
Set up your profilePart of the Mediband family. Designed in Australia since 2004.
Long QT runs in families
The Better Health Channel explains that long QT has an autosomal dominant inheritance pattern — one changed gene is enough to cause it — and encourages biological family members of anyone diagnosed to see a cardiologist. healthdirect adds that checking family may involve an ECG or genetic testing. The Australian Genetic Heart Disease Registry supports families living with inherited heart conditions. For children with long QT, make sure every adult responsible for them — school, sport, camps — knows the plan; our guide to setting up emergency contacts helps.
Keeping it current
Update your record whenever a medicine changes, after any device check or replacement, after any event, and after every cardiology review. The most useful line on the whole record is the one most often out of date: the list of medicines to avoid.
FAQs
What is long QT syndrome?
healthdirect describes it as a disorder of the heart’s electrical system that can cause episodes of fast, disordered heartbeats called arrhythmias, named after its pattern on an ECG. It can cause fainting, seizures and, if the rhythm continues, cardiac arrest and possibly sudden death.
Which medicines can make long QT syndrome worse?
The Better Health Channel lists some antiarrhythmic medicines, antibiotics, antidepressants, antipsychotics, anti-nausea medicines and diuretics, including some over-the-counter medicines. healthdirect advises telling your doctors you have LQTS before they prescribe and checking with your pharmacist before any new medicine.
What can trigger a long QT event?
The Better Health Channel lists exercise, being startled by a loud noise such as a car horn, ringing phone or alarm clock, exams and other stressful situations, and anger or crying.
When should someone be checked for long QT syndrome?
If they faint for no apparent reason, faint during or shortly after exercise or emotional excitement, or have a family history of unexplained fainting, sudden death or long QT syndrome. Diagnosis is by an ECG.
What should I do if someone with long QT collapses?
If they are unresponsive and not breathing normally, call Triple Zero (000), start CPR and send someone for the nearest defibrillator, following standard CPR and defibrillator steps.
Is long QT syndrome inherited?
Usually. healthdirect says it is usually genetic and present from birth, and the Better Health Channel explains it has an autosomal dominant inheritance pattern. Close family members should be checked with an ECG or genetic testing.
What should a long QT syndrome medical ID say?
On the band: “long QT syndrome”, “ICD” if you have one, “check QT-prolonging drugs” and a number that opens your record. In the record: diagnosis, medicines, device details, medicines to avoid, triggers, your cardiologist and emergency contacts.
Sources
- healthdirect — Long QT syndrome — (reviewed October 2023) what LQTS is, diagnosis, treatment and telling your doctors.
- Better Health Channel — Long QT syndrome — warning signs, medicine classes, triggers, treatment and inheritance.
- Australian Genetic Heart Disease Registry — support for families with inherited heart conditions.
- ANZCOR Guideline 2 — Managing an Emergency — checking for alert jewellery and devices.
Disclaimer: This article is general information about recording long QT syndrome details for emergencies, not medical advice. The medicine groups named come from published Australian health information; which specific medicines you should avoid is for your cardiologist to advise. Never stop a prescribed heart medicine without medical advice. In an emergency, always call Triple Zero (000). For non-urgent health advice, call healthdirect on 1800 022 222 (NURSE-ON-CALL 1300 60 60 24 in Victoria, 13 HEALTH 13 43 25 84 in Queensland).
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