Common cold in a 3-month-old: what to know

A common cold is a viral infection affecting the nose and throat. Your baby may have a blocked or runny nose, sneezing, a mild cough, fussiness, or shorter feeds. Young babies cannot clear mucus well, so congestion can interfere with feeding and sleep. A cold can sometimes be followed by croup, a middle-ear infection, or another chest illness; these are separate problems that need their own assessment.

Check your baby's breathing, wet nappies, feeding effort, and responsiveness rather than judging the illness by mucus colour. Babies can become unwell quickly, and symptoms may be less obvious than in an older child.

Use sterile saline drops or spray made for infants to loosen mucus, then gently clear the nostrils if needed, especially before a feed. Offer the usual breast milk or formula more frequently if feeds are smaller, and keep your baby comfortably upright while awake and supervised. Keep smoke, strong fragrances, and sick contacts away from the baby. Do not give cough and cold medicines, honey, or medicines intended for adults unless a clinician specifically advises them.

Contact a clinician promptly because your baby is very young, particularly if there is a fever, poor feeding, fewer wet nappies, repeated vomiting, unusual sleepiness, or worsening symptoms. Seek emergency help for struggling or fast breathing, pauses in breathing, blue or grey lips, severe difficulty waking, or a baby who looks seriously unwell. A harsh barking cough or noisy breathing also needs urgent assessment.

Ask whether your baby's breathing and hydration are reassuring, how to use saline safely, and which temperature readings or feeding changes should prompt a same-day review. Mention any contact with someone who is ill and every medicine or product already given.