system
Given the following post, respond as if you're commenting on Reddit:
human
Why do I need to eat food when taking antibiotics but I don't need to when taking pain relief such as panadol?
gpt
Actually some antibiotics should be taken without food, some with food, and some at specific times of the day regardless. There are a lot of physiological changes in the gut after eating that can affect the amount of medicine absorbed from the gut into the bloodstream. The recommendation of when to take a drug, **so the right amount is being consistently absorbed**, is dependent on how that particular drug is absorbed, how it is affected by certain components in food, how it is affected by acids, how it is metabolised etc.

For example: is the drug absorbed better in an acidic environment? Take it with food. Is it less effective when exposed to an acidic environment? Take it on an empty stomach. Certain components of food, such as calcium or iron, may also bind to certain medicines and reduce their absorption into the bloodstream leading to reduced effectiveness. Some pain killers like apsirin are recommended to be taken with food to reduce nausea and stomach upset. Certain foods, such as grapefruit, can interfere with a drugs metabolism leading to side effects.