Immunizations are safe, but they can have some risks and side effects.

Fortunately, most are fairly mild, like pain and fever.
How Long Do Side Effects of Immunizations Last?
And most vaccine side effects go away quickly.
For example, fever and fussiness, two of the most common vaccine reactions, typically only lasts a day or two.
Others can last a little longer, but still usually go away on their own:
- when kids get a rash after their MMR vaccine, it might last three or four days
- even when kids get swelling of an entire arm or leg after the DTaP shot is given, it might last for 1–7 days
- pain at the injection site typically only lasts a few days
- shoulder injury related to vaccine administration (SIRVA) can last months and sometimes doesn’t go away
- arthritis after a rubella containing vaccine, which mostly occurs in adults, typically only lasts a few days
- febrile seizures are usually brief and rarely lead to non-febrile seizures
- immune thrombocytopenic purpura (ITP) after a measles containing vaccine resolves in two weeks to six months, typically without any treatment
- intussusception after a rotavirus vaccine resolves with treatment, either an air contrast enema or surgery
- Guillain-Barré Syndrome after a seasonal flu vaccine, which is very rare, resolves in the majority of people over a period of years
Do any have more long lasting effects?
VAPP or vaccine-associated paralytic polio after the oral polio vaccine might not resolve. Fortunately, it only occurs in about 1 in every 1.27 million children receiving their first dose of OPV. It is even less common after bOPV, which is oral polio vaccine that is now being used. And won’t happen at all once we stop using oral polio vaccines.
Encephalitis or encephalopathy after a pertussis or a measles, mumps, and rubella virus containing vaccine might also lead to long lasting effects.
And some, like anaphylaxis, are life-threatening.
Fortunately, most long-term vaccine studies have shown that immunizations are safe, rarely causing severe reactions, and don’t have many long term side effects.
What to Know About How Long Immunization Side Effects Last
Most vaccine side effects are mild and only last a few days.
More on Immunization Side Effects
- Do Flu Vaccines Have More Reported Side Effects Than Other Vaccines?
- Is Meningitis a Side Effect of Vaccines?
- How Many People Die in the USA Every Year from Being Vaccinated?
- Understanding the Vaccine Injury Table
- Vaccine Reactions – Is This Normal?
- Myths About Warnings and Adverse Reactions in the MMR Package Inserts
- Using and Misusing VAERS Reports
- CDC – Possible Side-effects from Vaccines
- AAP – Vaccines and Side Effects: The Facts
- WHO – Six common misconceptions about immunization
- Vaccine Side Effects and Adverse Events
- Should Your Child See a Doctor for these Immunization Reactions?
- Treatment of local injection reactions
- Medical Management of Vaccine Reactions in Children and Teens
- WHO – Adverse events following immunization
- ACIP – Preventing and Managing Adverse Reactions
- Side Effects from Vaccines
- Ask the Experts: Vaccine Safety
- Side effects of childhood vaccines are extremely rare, new study finds
- Adverse skin reactions to vaccines
- A Serious Reaction After Vaccination Rarely Occurs Again With Later Immunization, Study Finds