# Why do we get fever after vaccination? **URL:** \ **Category:** MBBS\ **Created:** [August 19, 2026, 5:59pm UTC](https://www.medboundhub.com/t/why-do-we-get-fever-after-vaccination/22742 "2026-08-19T17:59:58Z")\ **Posts on this page:** 19\ **Page:** 1
**Author:** ![mansyy](https://avatars.discourse-cdn.com/v4/letter/m/c37758/32.png) [@mansyy](https://www.medboundhub.com/u/mansyy)\ **Post date:** [August 19, 2026, 5:59pm UTC](https://www.medboundhub.com/t/why-do-we-get-fever-after-vaccination/22742/1 "2026-08-19T17:59:59Z")
# Why do we get fever after vaccination? We usually get fever when our body is fighting against any infection. During fever our body temperature rises above 38 degree celsius.But we can even experience fever after taking an vaccine. We will know that in detail through this post. ## What happens inside our body after taking any vaccine? - Vaccines contain inactivated and harmless part of the pathogen, nowadays there is a blueprint vaccine as well which contains RNA or DNA of that pathogen instead the whole pathogen. - We take vaccine to protect our immune system against a particular pathogen. It can be a virus or a bacteria. - After taking an vaccine, antigens in vaccine are released in our body. Our immune system makes antibodies against those antigens. - Time taken by our immune system to make memory cells (which create antibodies when we encounter the infection in real) and the type of vaccine decides the next dose. - We can get fever because our body heats up while fighting against the harmless antigens from vaccine by activating our immune system and producing antibodies(though it is not necessary to get fever it can be seen or cannot be). - Tiredness, discomfort and swelling at the site of vaccine injection is also commonly seen. MBH/PS ---
**Author:** ![Riddhi\_1987](https://yyz1.discourse-cdn.com/flex033/user_avatar/www.medboundhub.com/riddhi_1987/32/5791_2.png) [@Riddhi\_1987](https://www.medboundhub.com/u/Riddhi_1987)\ **Post date:** [August 20, 2026, 6:08am UTC](https://www.medboundhub.com/t/why-do-we-get-fever-after-vaccination/22742/2 "2026-08-20T06:08:01Z")
No, it is not necessary to get a fever after a vaccination. While a mild fever is a common and normal sign that the immune system is actively building protection, not everyone will experience fever. The vaccine is still working effectively even if you or your children have zero side effects. ---
**Author:** ![drbhavyarvirmani](https://yyz1.discourse-cdn.com/flex033/user_avatar/www.medboundhub.com/drbhavyarvirmani/32/5728_2.png) [@drbhavyarvirmani](https://www.medboundhub.com/u/drbhavyarvirmani)\ **Post date:** [August 20, 2026, 6:16am UTC](https://www.medboundhub.com/t/why-do-we-get-fever-after-vaccination/22742/3 "2026-08-20T06:16:37Z")
For post vaccination fever how many days fever is considered to be acceptable and what temperature! ---
**Author:** ![mansyy](https://avatars.discourse-cdn.com/v4/letter/m/c37758/32.png) [@mansyy](https://www.medboundhub.com/u/mansyy)\ **Post date:** [August 20, 2026, 11:33am UTC](https://www.medboundhub.com/t/why-do-we-get-fever-after-vaccination/22742/4 "2026-08-20T11:33:23Z")
It depends on the type of vaccine and the guidelines associated with it ---
**Author:** ![drbhavyarvirmani](https://yyz1.discourse-cdn.com/flex033/user_avatar/www.medboundhub.com/drbhavyarvirmani/32/5728_2.png) [@drbhavyarvirmani](https://www.medboundhub.com/u/drbhavyarvirmani)\ **Post date:** [August 20, 2026, 11:58am UTC](https://www.medboundhub.com/t/why-do-we-get-fever-after-vaccination/22742/5 "2026-08-20T11:58:40Z")
Ok but some generic sign needs to be explained to the people taking vaccinations ---
**Author:** ![Jinal](https://yyz1.discourse-cdn.com/flex033/user_avatar/www.medboundhub.com/jinal/32/5281_2.png) [@Jinal](https://www.medboundhub.com/u/Jinal)\ **Post date:** [August 21, 2026, 9:59am UTC](https://www.medboundhub.com/t/why-do-we-get-fever-after-vaccination/22742/6 "2026-08-21T09:59:50Z")
Noted mild fever and weakness after vaccination which usually improves with rest. Immunological response is good indication of vaccine effectiveness. ---
**Author:** ![Mkrishna](https://yyz1.discourse-cdn.com/flex033/user_avatar/www.medboundhub.com/mkrishna/32/5442_2.png) [@Mkrishna](https://www.medboundhub.com/u/Mkrishna)\ **Post date:** [August 21, 2026, 11:41am UTC](https://www.medboundhub.com/t/why-do-we-get-fever-after-vaccination/22742/7 "2026-08-21T11:41:17Z")
Great explanation! Fever after vaccination is usually a sign that the immune system is responding and building protection. The difference in how it feels can depend on the cause, intensity, and the body’s immune response. ---
**Author:** ![PriyankaRathore](https://yyz1.discourse-cdn.com/flex033/user_avatar/www.medboundhub.com/priyankarathore/32/5774_2.png) [@PriyankaRathore](https://www.medboundhub.com/u/PriyankaRathore)\ **Post date:** [September 9, 2026, 5:02am UTC](https://www.medboundhub.com/t/why-do-we-get-fever-after-vaccination/22742/9 "2026-09-09T05:02:29Z")
When we get fever after vaccination the symptoms differ in sense that we don’t get other symptoms related to infections like sore throat or cough. It is just one or two days fever and nothing like viral fever symptoms. ---
**Author:** ![Vaishnavi\_13](https://yyz1.discourse-cdn.com/flex033/user_avatar/www.medboundhub.com/vaishnavi_13/32/5780_2.png) [@Vaishnavi\_13](https://www.medboundhub.com/u/Vaishnavi_13)\ **Post date:** [September 9, 2026, 7:06am UTC](https://www.medboundhub.com/t/why-do-we-get-fever-after-vaccination/22742/10 "2026-09-09T07:06:35Z")
I think the difference is that fever after vaccination is usually a result of the immune system responding to the vaccine, whereas fever due to an infection may be accompanied by other signs and symptoms depending on the infection. ---
**Author:** ![sumana](https://yyz1.discourse-cdn.com/flex033/user_avatar/www.medboundhub.com/sumana/32/5786_2.png) [@sumana](https://www.medboundhub.com/u/sumana)\ **Post date:** [September 9, 2026, 8:05am UTC](https://www.medboundhub.com/t/why-do-we-get-fever-after-vaccination/22742/11 "2026-09-09T08:05:50Z")
Experienced fever symptoms after the vaccination in my child but not for all the vaccines, the fever was just above the normal body temperature not like viral or bacterial fever symptoms. ---
**Author:** ![Arushi522002](https://yyz1.discourse-cdn.com/flex033/user_avatar/www.medboundhub.com/arushi522002/32/3700_2.png) [@Arushi522002](https://www.medboundhub.com/u/Arushi522002)\ **Post date:** [September 9, 2026, 6:33pm UTC](https://www.medboundhub.com/t/why-do-we-get-fever-after-vaccination/22742/12 "2026-09-09T18:33:05Z")
This was very informative ---
**Author:** ![ayushinarang](https://yyz1.discourse-cdn.com/flex033/user_avatar/www.medboundhub.com/ayushinarang/32/5772_2.png) [@ayushinarang](https://www.medboundhub.com/u/ayushinarang)\ **Post date:** [September 10, 2026, 8:48am UTC](https://www.medboundhub.com/t/why-do-we-get-fever-after-vaccination/22742/13 "2026-09-10T08:48:16Z")
Fever after vaccination is more of an indication that the vaccine is working. Because the immune system is learning to fight against a real infection that may occur in future using a harmless antigen that we just introduced instead of real rapidly multiplying pathogen the fever can feel different. That’s my theory, please correct me if I am wrong. ---
**Author:** ![Sana1](https://yyz1.discourse-cdn.com/flex033/user_avatar/www.medboundhub.com/sana1/32/5775_2.png) [@Sana1](https://www.medboundhub.com/u/Sana1)\ **Post date:** [September 10, 2026, 9:54am UTC](https://www.medboundhub.com/t/why-do-we-get-fever-after-vaccination/22742/14 "2026-09-10T09:54:21Z")
The fever after vaccination feels different from the normal fever because in this case we are not actually sick, your body is just practicing. This fever is not actually a fever i.e. Contagious, it only occurs for short period of time and will get better in 24-48 hrs. ---
**Author:** ![VividReef66](https://yyz1.discourse-cdn.com/flex033/user_avatar/www.medboundhub.com/vividreef66/32/5937_2.png) [@VividReef66](https://www.medboundhub.com/u/VividReef66)\ **Post date:** [September 23, 2026, 3:11pm UTC](https://www.medboundhub.com/t/why-do-we-get-fever-after-vaccination/22742/15 "2026-09-23T15:11:34Z")
Not everyone can experience fever after vaccination, and everyone reacts differently to them; some may feel slightly feverish while others may feel very ill with a high fever. ---
**Author:** ![ashimasherlin](https://yyz1.discourse-cdn.com/flex033/user_avatar/www.medboundhub.com/ashimasherlin/32/5949_2.png) [@ashimasherlin](https://www.medboundhub.com/u/ashimasherlin)\ **Post date:** [September 24, 2026, 3:08pm UTC](https://www.medboundhub.com/t/why-do-we-get-fever-after-vaccination/22742/16 "2026-09-24T15:08:05Z")
Interesting read! Post-vaccination fever is mainly due to immune activation and inflammatory responses, rather than an actual infection. It’s usually mild and temporary—a fascinating example of how our immune system responds to vaccination. ---
**Author:** ![Mariyam](https://yyz1.discourse-cdn.com/flex033/user_avatar/www.medboundhub.com/mariyam/32/5951_2.png) [@Mariyam](https://www.medboundhub.com/u/Mariyam)\ **Post date:** [September 24, 2026, 4:10pm UTC](https://www.medboundhub.com/t/why-do-we-get-fever-after-vaccination/22742/17 "2026-09-24T16:10:18Z")
I also always thought that we get fever because our body is developing defense against the foreign entity that was injected. But it became more clear after I studied about it. ---
**Author:** ![Aniket](https://yyz1.discourse-cdn.com/flex033/user_avatar/www.medboundhub.com/aniket/32/1834_2.png) [@Aniket](https://www.medboundhub.com/u/Aniket)\ **Post date:** [September 24, 2026, 4:42pm UTC](https://www.medboundhub.com/t/why-do-we-get-fever-after-vaccination/22742/18 "2026-09-24T16:42:45Z")
Our immune cells release interleukins which act on hypothalamus and increase body temperature ---
**Author:** ![dr\_sneha\_p](https://yyz1.discourse-cdn.com/flex033/user_avatar/www.medboundhub.com/dr_sneha_p/32/5882_2.png) [@dr\_sneha\_p](https://www.medboundhub.com/u/dr_sneha_p)\ **Post date:** [September 24, 2026, 5:51pm UTC](https://www.medboundhub.com/t/why-do-we-get-fever-after-vaccination/22742/19 "2026-09-24T17:51:56Z")
Fever after vaccination is completely normal. It’s just an indication that our immune system is actively reponding.There are some people who never experience fever after vaccination. It’s because immune reactivity varies from person to person. ---
**Author:** ![ashimasherlin](https://yyz1.discourse-cdn.com/flex033/user_avatar/www.medboundhub.com/ashimasherlin/32/5949_2.png) [@ashimasherlin](https://www.medboundhub.com/u/ashimasherlin)\ **Post date:** [October 7, 2026, 2:55pm UTC](https://www.medboundhub.com/t/why-do-we-get-fever-after-vaccination/22742/20 "2026-10-07T14:55:15Z")
An Interesting explanation of post-vaccination fever. the fever can feel different because it is part of the immune system’s response to the vaccine rather than a active infection. Usually, these mild symptoms are temporary and resolve as the immune response develops.