The short explanation
No, do not wait. A heart that has been racing for hours with shaking, sweating and breathlessness needs to be checked today. If you also have chest pain, fever, confusion, fainting or severe breathlessness, call 112 or go to the nearest emergency department now. In someone with an overactive thyroid, this can be a fast or irregular heart rhythm, or less often a severe thyroid flare, and both need prompt treatment. Emergency teams can do an ECG, check your thyroid levels and treat the heart rate.
What depends on your situation
The parts of this that change from woman to woman. Uncertainty is stated, not hidden.
- After fifty, an overactive thyroid more often triggers an irregular rhythm called atrial fibrillation, which raises the risk of stroke if untreated.
- Triggers can include missed medicine, an infection, a recent change in treatment or iodine-containing contrast from a scan.
- Take your medicines and recent reports with you, and tell the doctors when your symptoms started.
What this answer cannot determine
The boundary of online education. These need a clinician who can see you.
- This answer cannot tell you what is happening to your heart. Only an examination and tests such as an ECG can do that.
Questions for your clinician
Take these with you. You can add any of them to an appointment card.
- Is my heart rhythm normal or irregular?
- Is my thyroid out of control, and why?
- Do I need medicine to slow my heart or protect against clots?
- What should I do if this happens again?
When to seek help
Clinician-approved guidance for this topic. When in doubt, being seen is never the wrong choice.
Emergency — call 112 now
- Call 112 or go to the nearest emergency department now if you have chest pain, fainting, fever, confusion or severe breathlessness with the racing heart.
Get help the same day
- If none of those are present, still get seen the same day at an emergency department or your doctor's clinic.
Sources
The evidence this explanation is built on.
- Hyperthyroidism MedlinePlus (NIH)
- Overactive thyroid (hyperthyroidism) NHS
- Thyroid diseases MedlinePlus (NIH)
Who wrote and reviewed this
Every AskHer answer names its author. A clinically reviewed answer also names the clinician who signed it off — if no clinician is named below, it has not been clinically reviewed.
- Author
- AskHer Editorial (AI-assisted draft) AskHer's editorial team — not an individual clinician Works in English, தமிழ், हिन्दी
- Clinical reviewer
- Nobody yet No clinician has signed this answer off, and no person on the editorial team has read it yet. That is what the “Written with AI assistance” label means. It is queued for an editor to read, and then for a clinician who works in this area. The sources it was drafted against are listed above.
- Review status
- Written with AI assistance — not yet reviewed by a person
- Last reviewed
- Not yet reviewed by a person
- Version
- 1
Correction history
Substantive changes are listed, not quietly edited away.
No corrections have been made since this answer was first published.
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