For a 5-month-old baby with a cough, nasal drops can sometimes be helpful, but it depends on the type of drops and the cause of the cough. Here are some important points to consider:

• Use only saline nasal drops: These are safe for infants and can help loosen mucus in the nose, making it easier for your baby to breathe.

• Avoid medicated nasal drops: Drops containing decongestants or other medications are generally not recommended for babies under 2 years old without a doctor's advice.

• Consult your pediatrician: Since your baby is very young, it's best to check with your doctor before using any nasal drops or other treatments for cough.

• Other supportive care: Keeping your baby hydrated, using a humidifier, and gently suctioning nasal mucus with a bulb syringe can also help relieve symptoms.

If your baby's cough is persistent, worsening, or accompanied by fever, difficulty breathing, or feeding problems, seek medical attention promptly. Always prioritize safety and professional guidance when treating infants.