Common Vaccine Side Effects and How to Deal with Them
Quick Answer
Yes, vaccines can cause mild side effects, but these are normal signs that your baby's immune system is responding - and they're far less risky than the diseases vaccines prevent. The most common reactions are fever (bukhar), fussiness, and swelling at the injection site, which typically resolve within 24-48 hours. Serious side effects are extremely rare. This guide will help you understand what's normal, what to do at home, and when to call your pediatrician.
What Happens When Your Baby Gets Vaccinated
Watch: Always look for this early hunger cues.Do you feed your baby only after they start crying?
Vaccines work by training your baby's immune system to recognize and fight specific diseases. When the vaccine is given, the body:
Recognizes the weakened/inactive germ or its parts
Produces antibodies to fight it
Remembers how to fight it in the future
The mild side effects you see (fever, irritability, swelling) are actually signs that the vaccine is working - the immune system is responding!
Common Vaccine Side Effects: What's Normal
General Reactions (All Vaccines)
Side Effect
How Common
Duration
What to Do
Mild fever (100-102°F)
Very common
1-2 days
Monitor, give fluids
Fussiness/crying
Very common
24-48 hours
Extra cuddles, feeding
Sleepiness
Common
24 hours
Let baby rest
Reduced appetite
Common
1-2 days
Offer feeds frequently
Swelling at injection site
Common
2-3 days
Cold compress
Redness at injection site
Common
2-3 days
Usually self-resolves
Vaccine-Specific Reactions
DPT/DTaP/Pentavalent:
Most common vaccine to cause fever
Swelling and redness at thigh/arm
May cause increased crying for 24-48 hours
Small, painless lump at injection site (can last weeks - normal!)
MMR (Measles, Mumps, Rubella):
Fever and mild rash may appear 7-12 days after vaccination
This is NOT the disease - just immune response
Usually mild and self-limiting
Rotavirus (Oral):
Mild diarrhea or vomiting
Irritability
Given orally, so no injection site reaction
BCG:
Small raised bump appears at site after 2-6 weeks
May develop pus and then scab - this is NORMAL
Do NOT apply any cream or medication to the BCG site
Leaves a permanent small scar
Hepatitis B:
Usually very mild reactions
Slight soreness at injection site
Step-by-Step Guide: Managing Vaccine Reactions at Home
Step 1: Before the Vaccine Appointment
Feed your baby well - A hungry or tired baby is fussier
Bring the vaccination card - For proper record-keeping
Dress baby in loose clothes - Easy access to thigh/arm
Stay calm - Babies sense parental anxiety
Step 2: Immediately After Vaccination
Wait 15-30 minutes at the clinic - To monitor for rare allergic reactions
Breastfeed or offer formula - Comforts baby and helps with pain
Note the time - To track when symptoms appear
Step 3: At Home - First 24-48 Hours
For Fever:
Give extra breastmilk or formula feeds
Keep baby lightly dressed
For low fever (100-102°F/37.8-39°C): No medicine needed, just fluids
For higher fever or discomfort: Give paracetamol drops (Calpol/Crocin) as prescribed by doctor
Do NOT give any medicine before checking with doctor
For Injection Site Pain/Swelling:
Apply clean, cool washcloth for 10-15 minutes
Avoid rubbing or massaging the site
Gentle movement of arm/leg is fine
Do NOT apply any balm, cream, or ice directly
For Fussiness:
Extra cuddles and skin-to-skin contact
Breastfeed on demand
Gentle rocking or walking
Distraction with songs or toys
Step 4: Continue Normal Feeding
Breastfed babies:
Feed more frequently if baby wants
Breastmilk provides comfort and hydration
Formula-fed babies:
Continue regular formula (NAN, Lactogen, Similac, etc.)
May need smaller, more frequent feeds
Ensure adequate fluid intake
Mixed feeding:
Prioritize breastfeeding for comfort
Supplement with formula as usual
Feeding Tips for Vaccinated Babies
Age-Specific Guidance
0-6 months (milk-only stage):
Only breastmilk or formula - no water, juice, or solids
Feed more frequently if baby is fussy
If baby refuses bottle, try breastfeeding or vice versa
6-12 months:
Continue breastmilk/formula as primary nutrition
Offer easy-to-digest solids if baby is eating
Increase fluid intake (water, dal ka paani)
1+ years:
Offer favorite foods that are easy to eat
Keep hydration high
Don't force food if appetite is low
Common Mistakes to Avoid
Pre-medicating with paracetamol - Don't give fever medicine before vaccines "just in case" - it may reduce vaccine effectiveness
Applying anything to BCG site - No cream, antiseptic, or band-aid
Skipping feeds - Baby needs nutrition and comfort
Panicking at mild fever - Low-grade fever is normal and expected
Massaging injection site - Can worsen swelling
Using ice directly - Use cloth-wrapped cool compress instead
Delaying next vaccine - Mild side effects are not a reason to skip future doses
When to Call the Doctor
Call Immediately / Go to Hospital if:
Fever above 104°F (40°C)
Baby is limp, unresponsive, or extremely weak
Seizures or convulsions
Difficulty breathing
Swelling of face, lips, or throat
Baby won't stop crying for 3+ hours
Rash that looks like bruises (not the normal MMR rash)
Injection site has increasing redness/swelling after 3 days
Call Doctor During Clinic Hours if:
Fever persists beyond 3 days
Swelling/redness continues beyond 7 days
Baby refuses all feeds for more than 6-8 hours
You're worried and need reassurance
Addressing Common Concerns
"Is the fever from vaccine or is baby sick?"
Vaccine fever usually:
Starts within 12 hours of vaccination (or 7-12 days for MMR)
Is low-grade (100-102°F)
Resolves within 48 hours
Baby is fussy but alert
Illness fever may have:
Other symptoms (runny nose, cough, diarrhea)
Higher temperature
Baby seems more unwell
"My baby's arm/thigh has a big lump"
Small lumps at DPT injection sites are very common and can last several weeks. They're not dangerous and will resolve on their own. Don't massage or apply anything.
"BCG site is oozing pus - is it infected?"
No, this is the normal BCG reaction! The site forms a small ulcer, may ooze, then scabs over. This process takes 4-6 weeks. Do NOT apply anything or cover it.
Expert Insight: As Dr. Sumitra says, 'Fed is best. Formula is a completely valid choice and provides excellent nutrition.'
FAQs
Q: Should I give Calpol/paracetamol before the vaccine?
A: No, don't pre-medicate. Studies suggest giving paracetamol before vaccines might reduce the immune response. Only give medicine after vaccination if baby has significant fever or discomfort, and only as advised by your doctor.
Q: My baby didn't get any fever after vaccination. Is the vaccine working?
A: Yes! Not all babies get fever after vaccines, and that's completely fine. The absence of side effects doesn't mean the vaccine isn't working. Every baby's immune system responds differently.
Q: Can I bathe my baby after vaccination?
A: Yes, you can give a normal bath. There's no need to avoid bathing. Just be gentle around the injection site and pat dry carefully.
Q: My baby had a fever after the last vaccine. Should I skip the next dose?
A: No, mild side effects are not a reason to skip vaccines. The diseases these vaccines prevent are far more dangerous than temporary fever or fussiness. Discuss specific concerns with your pediatrician.
Q: Baby vomited the rotavirus drops. What should I do?
A: If baby spits up or vomits within a few minutes of receiving oral rotavirus vaccine, inform your doctor. They'll decide if a repeat dose is needed (usually not necessary if baby retained most of it).
Q: Is it safe to breastfeed after baby gets vaccinated?
A: Absolutely! Breastfeeding is one of the best ways to comfort your baby after vaccination. It provides nutrition, hydration, and emotional comfort. Feed on demand.
Q: My baby is formula-fed. Which formula is best after vaccination?
A: Continue with your regular formula (NAN, Lactogen, Similac, Aptamil, or whatever baby is used to). There's no need to change formula after vaccination. If baby seems fussier, you can offer smaller, more frequent feeds.
---
This article was reviewed by a pediatrician. Last updated: January 2025
---
Need personalized guidance?Book a consultation with our pediatricians or explore our Care Plans for 24/7 expert support!
Get 24/7 Expert Pediatric Care
Access 50+ pediatricians on WhatsApp anytime. Get instant answers for all your baby health concerns.
