Oxygen and water are both poisonous in high concentrations. The dose makes everything.
Next time you take antibiotics think about that "they never heal anything" stuff you said. It's true that some diseases just can not be healed yet, like abnormalities in your hormones and basically every disease that affects neurotransmitters so you have to come back every time to get your meds but at least it makes people's lives better for the time being.
When's the last time a person has died from too much oxygen or water? Please stop trying to justify everything as a poison and realize there is a huge difference in ingesting too much chocolate and ingesting cocaine. One will kill you instantly if you go a little overboard, the other not so much, even if you go way overboard.
Furthermore antibiotics *help* you fight off only certain bacterias but do nothing for viruses, they aren't a cure and don't heal you, your own body does that. I'll go as far and say they do more damage in the long run because your body becomes reliant on them instead of fighting off disease(s) on it's own. People who take flu shots every year are more susceptible to getting worse flu's because their own system forgets how to do it on it's own. That sounds like a problem to me, not help.