system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What is the difference between paracetamol and ibuprofen?

What is the difference between them? I use both willy nilly just as pain relief for headaches mainly.
gpt
Ibuprofen is an NSAID (Non-Steroid Anti-Inflammatory Drug), this means it acts by inhibiting the enzyme COX, reducing synthesis of prostaglandin which is both central in the **inflammatory response** as well as **pain response**.

NSAID shouldn't be taken for too long because they **can cause gastric ulcers** (prostaglandins act as vasodilators (increasing radius of arteries) and the gastric mucosa is VERY dependent on good blood flow to protect against the acid environment).

Paracetamol isn't an NSAID. The mechanism of actions is not well understood but it is believed that it also act in some way on COX. Paracetamol can be toxic in large doses, but is usually used as the pain reliever of choice if you have to take a pain reliever for an extended period of time (since the alternative NSAID cause gastric ulcers). **Paracetamol is not anti-inflammatory.**