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

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.

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This article was reviewed by a pediatrician. Last updated: January 2025

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