system
Given the following post, respond as if you're commenting on Reddit:
human
Why is it recommended to avoid lying down after taking iron supplements?

The instructions recommend staying upright for 30 minutes afterwards, why is that? I wonder why don't I see this with things like antihistamines or painkillers. It is a 200mg iron fumarate supplement, if that helps.
gpt
Some medicines - such as iron supplements - can cause ulceration of the oesophagus if they do not pass cleanly into the stomach. 

Lying down after taking an iron supplement can increase the chance of this occurring so it is advised against for a period of time.