Depending on how old your toddler is honey mixed with warm water to good for a cough, and saline drops for a stuffy nose and humidifier mixed with essential oils are best.
Breastfeeding! Okay, besides that, because most have stopped by this time (except weird ones like me 😅) Prevention is where it’s at, then you have to let it run its course if he catches anything. Wash hands a lot. If you have him in daycare, there is very little you can do. Keeping the immune system strong (breastfeeding! Okay, I’ll stop) is the best way to prevent it shortage infections, but most of that is just getting enough vitamin D, eating a healthy diet, and being mobile, which all toddlers are.
How old is he? And does he go to daycare or school yet? I try to give my son elderberry syrup and smart pants gummies for vitamins. Use a humidifier when he sleeps. Use saline spray to loosen up tough mucus or maybe even nasal irrigation. Sitting in a hot steaming shower. I also give him warm honey lemon water. I’ve been to the urgent care who provided a nebulizer and also to his pediatrician who I ask to prescribe me a nebulizer