I used to suffer from frequent colds and catarrhal conditions during my twenties and thirties. During late thirties, I once suffered the usual attack of cold in winter season and took a course of antibiotics on the prescription of the doctor as the cold was attended by high fever. I had profuse discharge of thick phlegm during the episode of cold. After taking the course of antibiotics, the catarrh dried up but after 15 days, I developed a big abscess on my trunk. The doctor got alarmed and prescribed another course of antibiotics, now stronger than before. But the abscess did not heal up under the antibiotic treatment. It ripened and burst after a week and the pain and discomfort caused by it continued for another week before it got healed.
After one month of this, I suffered a mild feverish condition along with vertigo for about a fortnight. The body temperature appeared to be slightly above normal which caused a feeling of discomfort. This condition continued for about 4 months thereafter.
I had the experience of the fruitlessness of antibiotics in colds that I was regularly developing and also the side effects of these antibiotics in development of abscess and later in the vertigo and the chronic mild feverish condition that I suffered from.
I think indiscriminate use of antibiotics is best avoided.