Persistent Elevated Temperature After AZ Vaccine: When to Seek Further Evaluation?

Persistent elevated body temperature for several days after receiving the AZ vaccine?

Hello Doctor, I received the AZ vaccine on August 5th.
After experiencing a high fever of 38.5°C for two days, my temperature has remained around 37.5°C and has not returned to normal.
Currently, my ear temperature is between 37.2°C and 37.4°C, and it occasionally rises to 37.6°C.
I have already been to the hospital for blood tests, urine tests, and a chest X-ray, all of which came back normal.
The doctor advised me to drink plenty of water.
However, it has been over ten days, and my temperature has not decreased, which is making me quite anxious.
If this continues, should I consider undergoing further tests?

Lai, 30~39 year old female. Ask Date: 2021/08/16

Dr. Liao Yaopan reply Family Medicine

Hello, typically the fever response after vaccination lasts about two days and usually subsides.
If the high temperature persists, it is advisable to return for a check-up to confirm if there are other factors causing it.
When seeking medical attention, you should inform the physician about when you received the vaccine and the environment you were in.
Online consultations are not equivalent to in-person medical visits and cannot provide diagnoses or treatment recommendations.
Changhua Hospital cares about you.

Reply Date: 2021/08/16

More Info

After receiving the AstraZeneca (AZ) vaccine, it is not uncommon for individuals to experience a range of side effects, including fever, fatigue, and localized pain at the injection site. These symptoms are typically mild to moderate and usually resolve within a few days. However, your situation of experiencing a persistent elevated temperature for over a month warrants further evaluation, especially since you have already undergone initial tests that returned normal results.

In general, a mild fever (defined as a body temperature between 37.5°C and 38.5°C) can be a normal response to vaccination as your immune system is activated to build protection against the virus. However, when the fever persists beyond a few days or is accompanied by other concerning symptoms, it is essential to consider other potential causes.
Given that you have already consulted with healthcare professionals and undergone blood tests, urinalysis, and chest X-rays, which all returned normal, it is less likely that your elevated temperature is due to an acute infection or a direct reaction to the vaccine. However, persistent symptoms can sometimes indicate other underlying conditions that may not be immediately apparent.

Here are some considerations and recommendations:
1. Monitor Symptoms: Keep a detailed log of your symptoms, including the frequency and duration of your elevated temperature, any other symptoms you may experience (like fatigue, headaches, or gastrointestinal issues), and any changes in your overall health. This information can be valuable for your healthcare provider.

2. Hydration and Nutrition: Continue to stay well-hydrated and maintain a balanced diet. Sometimes, dehydration or nutritional deficiencies can contribute to feelings of malaise and may affect body temperature regulation.

3. Follow-Up with Your Doctor: If your elevated temperature persists beyond a few more days, or if you develop new symptoms, it is advisable to follow up with your primary care physician or a specialist. They may recommend further investigations, such as additional blood tests to check for inflammatory markers, autoimmune conditions, or other underlying issues that could explain your symptoms.

4. Consider Other Factors: Sometimes, factors unrelated to the vaccine can cause persistent low-grade fever, such as chronic infections, autoimmune disorders, or even stress and anxiety. Discussing these possibilities with your doctor can help narrow down the cause.

5. Seek Immediate Care for Worsening Symptoms: If you experience any alarming symptoms, such as severe headaches, difficulty breathing, chest pain, or significant changes in your health status, seek immediate medical attention.

In conclusion, while a mild fever can be a normal reaction to the AZ vaccine, persistent elevated temperatures that last for weeks should be evaluated further. It is essential to communicate openly with your healthcare provider about your ongoing symptoms and any concerns you may have. They can guide you on the next steps and help ensure that any underlying issues are addressed appropriately.

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