Can Taking Fever Reducers Affect Vaccine Efficacy? A Patient's Concern

Took antipyretics?

Hello doctor, last night I received the AZ vaccine and took a Tylenol beforehand.
After taking a shower and doing some work, I went to bed around midnight.
Suddenly, around 4 AM, I felt very cold and started shivering.
Not long after, at 5 AM, I developed a fever.
I took the antipyretic medication prescribed by my doctor for a cold, as he mentioned I might have a fever after the vaccination.
Initially, my temperature was 38.5°C, but after taking the medication, it rose to 39.3°C.
I then used an ice pack and kept drinking water, feeling dizzy, and slept until 7 AM, when I woke up to find I was sweating and my temperature had returned to 37.3°C.
Later, my family advised me to take Tylenol, which I did.
However, I just found out that taking non-steroidal anti-inflammatory drugs (NSAIDs) might reduce antibody production.
The medication I took is called TONZOUGE.
Before my vaccination yesterday, I was worried about having a cold and taking medication, and I intended to show my medication bag to the doctor, but it seemed he could see it on his computer.
He told me it was fine for me to take anything.
I saw conflicting information online; some say it's okay to take Tylenol, while others say it doesn't matter.
I'm concerned about whether taking one dose will have a significant impact.
I'm worried that it might negate the effects of the vaccine.
At that moment, I was feeling dizzy and thought it was close at hand, so I took it.

Xiao, 10~19 year old female. Ask Date: 2021/09/11

Dr. Hong Yuanbin reply Internal Medicine

Hello, some studies abroad have indeed shown that using antipyretics, such as acetaminophen (Tylenol), may slightly reduce the effectiveness of vaccines, but it does not render the vaccine ineffective.
It is recommended that if you have a mild fever or are only slightly uncomfortable, such as feeling dizzy, you can manage without taking antipyretics.
However, if you are feeling very unwell, for example, if you have a high fever or are in significant pain, it is advisable to take medication.
This will not negate the benefits of the vaccine.
Thank you for your question.

Reply Date: 2021/09/11

More Info

When it comes to the administration of vaccines, particularly in the context of fever reducers, there are several important considerations to keep in mind. Your concern about whether taking fever reducers, such as acetaminophen (commonly known as Tylenol) or non-steroidal anti-inflammatory drugs (NSAIDs), can affect the efficacy of the vaccine is valid and deserves a thorough explanation.

Firstly, it is essential to understand that vaccines work by stimulating the immune system to produce a response against a specific pathogen. This response often includes the production of antibodies, which help protect against future infections. After vaccination, it is common for individuals to experience mild side effects, including fever, fatigue, and soreness at the injection site. These symptoms are generally a sign that the immune system is responding to the vaccine.

Regarding the use of fever reducers, research has shown that taking acetaminophen or NSAIDs after vaccination does not significantly impair the immune response or the efficacy of the vaccine. The Centers for Disease Control and Prevention (CDC) and other health organizations have indicated that while there may be a theoretical concern that these medications could dampen the immune response, the evidence does not support a clinically significant impact on vaccine efficacy. Therefore, if you find yourself experiencing discomfort or fever after vaccination, it is generally acceptable to take these medications to alleviate your symptoms.

In your case, you mentioned taking a fever reducer before and after receiving the vaccine. It is understandable to be concerned about the potential effects on the vaccine's efficacy, especially after experiencing a fever. However, based on current medical guidelines and research, taking a single dose of acetaminophen or an NSAID is unlikely to negate the benefits of the vaccine. The key point is that the immune system can still mount a robust response even if fever reducers are used.

Moreover, it is important to note that the timing of when you take these medications can also play a role. If you take a fever reducer before the vaccine, it may not be as effective in preventing post-vaccination symptoms since the immune response is still being initiated. However, taking it after experiencing symptoms is generally considered acceptable.

In summary, while it is natural to worry about the implications of taking fever reducers after vaccination, current evidence suggests that doing so will not significantly affect the vaccine's efficacy. It is always advisable to consult with your healthcare provider regarding any medications you are taking, especially in the context of vaccination. They can provide personalized advice based on your medical history and current health status.

In conclusion, if you have taken a fever reducer after your vaccination, there is no need to panic. Your immune system is still capable of responding to the vaccine, and you should continue to monitor your symptoms. If you experience prolonged fever or any concerning symptoms, it is wise to seek medical attention. Remember to stay hydrated and rest, as these are crucial components of recovery after vaccination.

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