A cough in a 5-month-old can sound alarming, but most of the time it’s caused by a common cold and will clear up on its own within a few days. Your main job is to keep your baby comfortable, help them breathe more easily, and watch for signs that something more serious is going on. Over-the-counter cough medicines are not safe for infants, so relief comes down to a handful of simple, effective techniques you can do at home.
Why Cough Medicine Is Off Limits
No cough or cold product containing a decongestant or antihistamine should be given to children under 2 years old. The FDA has warned that serious and potentially life-threatening side effects, including convulsions, rapid heart rate, and death, have been reported in young children given these products. Manufacturers have voluntarily relabeled them to say “do not use in children under 4 years of age.” For a 5-month-old, there is no safe over-the-counter cough suppressant.
Honey, which works well as a cough soother for older children, is also dangerous for any baby under 12 months. It can contain spores that cause infant botulism, a severe form of food poisoning. Do not add honey to your baby’s food, water, formula, or pacifier.
Clear the Nose With Saline and Suction
Babies this age breathe primarily through their noses, so a stuffy nose often triggers coughing. Clearing mucus is one of the most effective things you can do. Start by placing your baby on their back and putting one to two drops of saline solution into each nostril. You can buy saline drops at any pharmacy, or make your own by dissolving a quarter teaspoon of salt in one cup of warm, previously boiled water. Wait a few seconds to let the saline thin the mucus.
Then squeeze a bulb syringe to push out the air, gently insert the tip into one nostril, and release the bulb. The suction pulls mucus into the syringe. Squeeze the contents into a tissue and repeat in the other nostril until most of the mucus is out. You can do this two to three times a day as needed. Try to do it before feedings rather than after, because the process can trigger vomiting on a full stomach. Wash the syringe in warm, soapy water and rinse it thoroughly after each use.
Use a Cool-Mist Humidifier
Adding moisture to the air helps loosen mucus and soothe irritated airways. A cool-mist humidifier in your baby’s room can make a noticeable difference, especially at night when coughing tends to worsen. Use a cool-mist model rather than a warm-mist vaporizer, which can cause burns. Fill it with distilled water to reduce the risk of spreading bacteria or mold into the air.
Keep humidity below 50 percent. If you notice condensation on the inside of your windows or dampness around the humidifier, turn down the output or use it less frequently. Empty the tank after each use and clean the unit regularly following the manufacturer’s instructions. Mold growing inside a humidifier can make a cough worse, not better.
Keep Your Baby Well Hydrated
Breast milk or formula is the right fluid for a 5-month-old with a cough. You don’t need to offer extra fluids beyond what your baby normally takes, but you do want to make sure they’re getting their usual amount. Babies who are congested or uncomfortable sometimes feed less eagerly, so offering smaller, more frequent feedings can help. If you’re breastfeeding, keep it up. Breast milk contains antibodies that offer extra protection against the viruses causing the illness.
Watch for signs that your baby isn’t getting enough fluid. A sunken soft spot on top of the head, sunken eyes, few or no tears when crying, noticeably fewer wet diapers, and unusual drowsiness or irritability all point to dehydration. If you notice any of these, contact your pediatrician.
What Different Coughs Sound Like
Most infant coughs come from ordinary colds and produce a wet, phlegmy sound. But certain cough types signal specific conditions worth recognizing.
A harsh, barking cough that sounds like a seal is the hallmark of croup. Croup happens when a virus causes swelling around the voice box and windpipe. Your baby’s voice may sound hoarse, and you might hear a high-pitched whistling sound (called stridor) when they breathe in. Symptoms are usually worst at night and typically last three to five days. Cool night air or sitting in a steamy bathroom for a few minutes can sometimes ease the swelling temporarily. If your baby makes that high-pitched breathing sound even when calm and not crying, that needs immediate medical attention.
A cough that comes in rapid-fire bursts followed by a whooping gasp, or a cough paired with wheezing (a tight, musical sound on exhale), also warrants a call to your pediatrician. Wheezing can indicate that the smaller airways are narrowing, which sometimes happens with RSV or bronchiolitis, both common in babies this age.
Signs Your Baby Needs Medical Attention
A 5-month-old falls in the 3-to-6-month age range where fever guidelines are strict. Call your pediatrician if your baby has a rectal temperature of 100.4°F (38°C) or higher, or any fever at all combined with seeming unwell.
Beyond fever, watch your baby’s breathing carefully. Several visible signs indicate your baby is working too hard to get air:
- Retractions: The skin pulls inward just below the neck or under the breastbone with each breath, as if the chest is sinking in.
- Nasal flaring: The nostrils spread wide open with each breath.
- Grunting: A small grunting sound at the end of each exhale, which is the body’s attempt to keep the lungs inflated.
- Color changes: A bluish tint around the mouth, inside the lips, or on the fingernails signals low oxygen and requires immediate emergency care.
- Sweating while cool: Your baby’s head may be sweaty, but the skin feels cool or clammy rather than warm. This can happen when breathing rate is very fast.
Any of these signs, along with refusing to feed, being unusually difficult to wake, or a cough that lasts more than a week without improving, are reasons to get your baby evaluated promptly.