It seems more complicated than it should be, doesn't it? Here are the rules.
1. No matter what kind of medication you take, take your morning dose first thing in the morning, on an empty stomach and with a full glass of water.
2. Don't take an supplements for at least an hour and a half before and after you take your medication.
3. If you take a multivitamin, take it at night so keep it far away from your thyroid medication as it could specifically have nutrients and minerals that directly interfere with absorption.
4. Ideally, don't drink anything except water for at least 30 minutes and wait an hour before eating. I am lax on this with my patients and only tell them not to eat or drink anything for 30 minutes because, well life gets in the way doesn't it.
5. If you take natural dessicated thyroid (things like armour thyroid, Nature-throid or westroid) be aware most people feel better with a second dose in the afternoon. Take this around 2:30-3:30pm which is a couple hours after lunch.
**Bonus tip: Don't let any of this advice make you so particular that you skip a dose as opposed to not taking it just right. Any absorption is better than none, so don't stress and thyroid-on.