In Ayurveda it is clearly described that if left untreated, this may turn into major diseases.
“divaswapnadidosheshchya pratishyaya jayte…
pratishyayadayo kaasah kaasat sanjyaatate kshayam…/”
Due to many reasons, one gets cold. If untreated cold may turn into coughing and finally cough which is left untouched converts into kshayam (the disease which eats the person day by day making him extreme weak and finally death (this may resemble to multi drug resistance tuberculosis).