A baby cannot catch a fever directly from you. Fever is not an illness; it’s your body’s response to fighting an infection. What can potentially pass to your baby is the underlying infection causing your fever, typically through respiratory droplets, direct contact, or (rarely) breast milk. The distinction matters because it changes what precautions you actually need to take.
Why Fever Itself Isn’t Contagious
Fever is a symptom, not a germ. When your immune system detects a virus or bacteria, it raises your body temperature to help fight the invader. That elevated temperature stays in your body. It doesn’t transfer to your baby through touch, breathing, or breast milk.
What can spread is the infection behind the fever. If you have the flu, for instance, the virus travels through tiny droplets released when you cough, sneeze, or talk. If you have a skin infection with open sores, direct contact is the risk. The fever is just a signal that your body is already fighting something, and by the time you notice it, you may have been contagious for hours or even days before your temperature spiked.
Common Infections and How They Spread
Most illnesses that cause fever in new mothers are respiratory viruses: colds, flu, COVID-19. These spread through airborne droplets, not through skin contact or breast milk. The flu, for example, is transmitted person to person via respiratory droplets and is not passed through breast milk, according to the CDC.
Herpes simplex virus (HSV) is a different story. It spreads through direct contact with an active sore. If you have a cold sore on your lip or a lesion on your skin, kissing your baby or letting them touch the sore is the risk, not breastfeeding. HSV is not transmitted through breast milk itself.
Mastitis, a breast infection common during breastfeeding, also doesn’t pose a risk to a healthy, full-term infant. Breast milk naturally contains bacteria from the nipple, skin, and milk ducts, so the presence of bacteria alone doesn’t mean your baby is in danger. Continuing to breastfeed through mastitis is considered safe.
Breastfeeding While Sick Is Usually Safe
For most common illnesses, you can and should continue breastfeeding. Your body starts producing specific protective antibodies as soon as it detects an infection, and those antibodies pass directly into your breast milk. This immune protection, primarily in the form of secretory IgA, is the first source of targeted immune defense your baby’s gut receives. It helps shape their gut bacteria and strengthens their ability to fight the very infection you’re dealing with. Stopping breastfeeding during a cold or flu actually removes this benefit.
There are a small number of infections where breastfeeding should be paused or stopped entirely. The CDC lists these specific situations:
- HIV when not on effective treatment or without sustained viral suppression
- HTLV-1 or HTLV-2 infection
- Ebola virus disease
- Active herpes lesions on the breast (you can still feed from the unaffected side if the sores are fully covered)
- Untreated active tuberculosis or untreated brucellosis
- Monkeypox until all lesions have fully healed
- Chickenpox that develops between 5 days before and 2 days after delivery
Outside of these situations, the standard guidance is to keep breastfeeding.
Taking Fever Reducers While Breastfeeding
If you’re nursing, both ibuprofen and acetaminophen are considered safe. Ibuprofen is often the preferred choice because it transfers into breast milk at extremely low levels. In studies, the amount reaching the infant through milk was estimated at roughly 0.2% of a standard pediatric dose, far too little to have any effect. At least 23 cases in published research documented infants breastfed during maternal ibuprofen use with no adverse effects reported. You don’t need to time your doses around feedings or pump and dump.
How to Reduce Your Baby’s Exposure
Since most infections spread through respiratory droplets and hand contact, practical hygiene makes the biggest difference. Wash your hands with soap and water before picking up your baby, before breastfeeding, and after blowing your nose or coughing. Alcohol-based hand gel works when soap isn’t available. If you’re coughing or sneezing frequently, wearing a mask while holding or feeding your baby reduces droplet exposure significantly.
Ask visitors who are feeling unwell or have cold or flu symptoms to stay away until they’ve recovered. Young infants have immature immune systems, and their risk from a household contact’s respiratory infection is real. You can’t always avoid exposing your own baby when you’re sick, but limiting the number of sick people in close contact helps.
When Your Baby’s Temperature Needs Attention
If your baby does develop a fever, the threshold is lower than you might expect. For any infant 90 days old or younger, a rectal temperature of 38.0°C (100.4°F) or higher is considered a fever and should prompt medical evaluation. This applies whether the temperature was taken at home or in a clinic. Unusually low temperatures, below 36.0°C (96.8°F), also signal a possible infection and warrant the same level of concern.
For babies under 28 days old, any fever triggers a full workup including blood tests, urine tests, and cultures. Between 29 and 60 days, the same diagnostic approach applies. These age cutoffs exist because very young infants can deteriorate quickly from infections that would be minor in older children. If your baby looks unwell, is unusually floppy, feeding poorly, or difficult to wake, that warrants immediate evaluation regardless of what the thermometer reads.
The reassuring reality is that being sick with a common cold or flu and caring for your baby is a normal part of parenting. Your baby’s biggest protection comes from the combination of good hand hygiene, continued breastfeeding, and knowing the temperature threshold that signals a problem.