[horsawlarway]

Doesn't adaptive immunity come into play here, though?

The goal of the antibiotics is to prevent the infection from killing you while buying time for your immune system to kick in and handle things.

Secondly, why would a second course be more harmful if the duration of the two courses combined is less total time than the initial prescribed amount?

If you feel better after 4 days of antibiotics, stop, get sick again and take 4 more days of antibiotics, you're still only dosing for 8 days. That's far better than a default of 2 weeks (14 days), and only barely worse than a 7 day course.

Now factor in the number of people who would have been just fine after 4 days, with no re-occurrence, and I'm really struggling to see why your advice is any better than: Treat when sick, stop when well. Even if you get sick again: treat when sick, stop when well.

[rplst8]

> I'm really struggling to see why your advice is any better than: Treat when sick, stop when well. Even if you get sick again: treat when sick, stop when well.

First, bacteria multiply very quickly. In the days between the first and second course, the bacteria could recolonize to the same number you had before. So it's not just as simple as taking the remainder of the course of antibiotics or even a slightly shortened one. You may need to take another full course. Additionally, those bacteria have had time to evolve and possibly become resistant.

Second, when you take antibiotics, it doesn't just kill the bad bacteria. Sometimes good bacteria dies as well. This can be disastrous to your health if done too many times.

[horsawlarway]

>>First, bacteria multiply very quickly. In the days between the first and second course, the bacteria could recolonize to the same number you had before. So it's not just as simple as taking the remainder of the course of antibiotics or even a slightly shortened one.

Sure, but where's the data collection that states taking it for a standard longer period is better than a repeated dose? Even if you have to bump the second dose to something like "Take until well plus 2 days, since you got sick again last time"? Not even mentioning that in most cases, your body actively gets better at handling the infection...

>>Second, when you take antibiotics, it doesn't just kill the bad bacteria. Sometimes good bacteria dies as well. This can be disastrous to your health if done too many times.

I agree, my issue is with the idea that taking it more times is ANY different than taking it longer. Why would two doses of seven days with a 3 day break between be any different than one 14 day dose?

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Edit: I want to add, I'm aware that the idea with a longer dose is to lower total levels of the bacteria below the amount the immune system can handle. And if we don't hit that target re-infection can occur. My issue is that we're assuming here that longer is always better, and I simply don't think we actually have data to back that up.

[yourkin]

How likely is a reinfection, given that the body's immune system should be in head-on war mode by that time?

[rplst8]

I don't know other than saying "likely enough that doctors don't recommend not finishing the full course." Seriously, I find it hilarious that on HN that questioning a doctor's, no an entire field of science's, opinion on the matter goes nearly unfettered, but question the science behind climate change research and you'd better duck.