Heart Palpitations After Moderna Vaccine: When to Seek Medical Attention?

Palpitations after receiving the Moderna vaccine?

I received the Moderna vaccine this morning.
On the same day, I experienced only arm soreness and a mild fever.
However, at night, while lying flat, I felt a noticeable heartbeat.
I measured my heart rate multiple times, and it ranged from the 80s to the 90s.
I was almost unable to sleep throughout the night; just as I was about to fall asleep, I would suddenly feel my heart beat and wake up.
After that, I might have dozed off for about 3 hours due to fatigue, but it was difficult to fall back asleep after waking up.
Sitting up, I did not feel a noticeable heartbeat.
In the morning, I drank more water and measured my heart rate every half hour, which was around 75-80, feeling some improvement.
However, I still cannot lie down to sleep; as soon as I do, I feel a pronounced heartbeat that makes it hard to rest.
Currently, my symptoms include a slightly elevated heart rate, mild chest tightness, body weakness, and arm soreness, but I do not have chest pain or significant shortness of breath.
The vaccination information mentioned that an increased heart rate is one of the side effects that requires medical attention, but it did not specify how severe or how long the symptoms should persist before seeking care.
I would like to know if I should continue to monitor my condition or if I need to seek medical attention.

Gao Xiaojie, 20~29 year old female. Ask Date: 2021/07/09

Dr. Hong Yuanbin reply Internal Medicine

Hello, the discomfort you described is indeed a common side effect of the Moderna vaccine, typically occurring within 48 hours.
Most symptoms improve within this timeframe.
If you still feel unwell after 48 hours or experience chest pain, it is advisable to seek medical attention.
Thank you for your question.

Reply Date: 2021/07/09

More Info

After receiving the Moderna vaccine, experiencing heart palpitations can understandably cause concern. It is important to differentiate between normal post-vaccination reactions and symptoms that may require medical attention.
In your case, the symptoms you describe—such as noticeable heartbeats when lying down, mild chest discomfort, and fatigue—are not uncommon after vaccination. Many individuals report transient side effects like arm soreness, fever, and fatigue, which typically resolve within a few days. However, the sensation of heart palpitations, especially if they are persistent or accompanied by other concerning symptoms, warrants careful consideration.

When to Seek Medical Attention
1. Persistent Symptoms: If your heart palpitations continue for more than a few days or worsen, it is advisable to consult a healthcare provider. While mild palpitations can be benign, persistent or worsening symptoms may indicate an underlying issue that needs to be addressed.

2. Associated Symptoms: If you experience additional symptoms such as severe chest pain, shortness of breath, fainting, or significant dizziness, seek immediate medical attention. These could be signs of more serious conditions, such as myocarditis or pericarditis, which have been reported in rare cases following mRNA vaccinations.

3. Difficulty Sleeping: The fact that you are unable to sleep comfortably due to the sensation of your heart beating strongly is also a concern. Sleep disturbances can exacerbate anxiety and lead to further health issues, so discussing this with a healthcare provider is important.

4. Monitoring Heart Rate: You mentioned that your heart rate has been between 75-90 beats per minute while sitting, which is generally within a normal range. However, if you notice significant fluctuations or if your heart rate increases substantially while at rest, this should be evaluated.

Recommendations
- Stay Hydrated: Continue to drink plenty of fluids, as dehydration can sometimes contribute to feelings of palpitations or increased heart rate.

- Rest and Relaxation: Engage in relaxation techniques such as deep breathing exercises, meditation, or gentle yoga to help manage anxiety and promote a sense of calm.

- Avoid Stimulants: Limit caffeine and other stimulants, as they can exacerbate feelings of palpitations and anxiety.

- Follow-Up: If symptoms persist or if you have any doubts about your condition, do not hesitate to reach out to your healthcare provider for further evaluation. They may recommend an ECG or other tests to ensure your heart is functioning properly.

Conclusion
While many individuals experience mild and transient side effects after receiving the Moderna vaccine, it is crucial to monitor your symptoms closely. If you have any concerns about your heart health or if your symptoms change, seeking medical advice is always the best course of action. Your health and peace of mind are paramount, and healthcare providers are there to help you navigate these concerns.

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