Question 1

How do painkillers actually work, and why do different ones suit different pain?

Accepted Answer

Because pain is not one thing. Different painkillers act at **different points in the chain** between tissue damage and the conscious experience of pain, which is why matching the drug to the mechanism matters more than matching it to the severity.

**Paracetamol.** The mechanism is still not fully established, but it acts substantially **centrally** — in the brain and spinal cord — rather than at the site of injury. It reduces pain and fever and has **little anti-inflammatory effect**. Safe at correct doses and genuinely dangerous in overdose, with liver damage that can occur at surprisingly modest excesses and may not produce symptoms until it is advanced.

**NSAIDs** — ibuprofen, naproxen, aspirin. These block **cyclo-oxygenase enzymes**, reducing prostaglandins, which are produced at the site of injury and both cause inflammation and sensitise nerve endings. So they work **where the damage is**, which is why they suit inflammatory pain — sprains, dental pain, period pain, arthritis — better than paracetamol does.

**Their cost:** prostaglandins also protect the stomach lining and support kidney blood flow, so NSAIDs carry risks of gastrointestinal bleeding, kidney impairment and cardiovascular effects, particularly in older people, and interact with several common medicines.

**Opioids** — codeine, morphine and others. These act on **opioid receptors** in the brain and spinal cord, reducing transmission and altering the emotional response to pain. Effective for acute severe pain, and **much less effective for chronic non-cancer pain** than was once believed — a recognition that has substantially changed prescribing.

**Codeine is a prodrug**, converted to morphine by an enzyme whose activity varies genetically: some people get almost no effect, others convert unusually fast, which is why it is avoided in children.

**Drugs for nerve pain** — certain antidepressants and anticonvulsants — work on nerve signalling rather than inflammation, which is why ordinary painkillers help neuropathic pain so poorly.

**Why combining works.** Paracetamol and an NSAID act differently and can be used together, giving better relief than either alone.

**Medication overuse headache** is a real and under-recognised problem.

General information, not medical advice.

Question 2

Why does the same drug have several different names?

Accepted Answer

Because a medicine carries up to three distinct names serving different purposes, and confusing them is a genuine source of medication errors. The chemical name describes the molecular structure

Question 3

Why doesn't pain always match the injury?

Accepted Answer

Because pain is produced by the brain, not delivered by the body — and the brain is weighing a great deal more than tissue damage when it decides how much to produce. The old model was wrong. For

Question 4

How does general anaesthesia work?

Accepted Answer

Remarkably well, and we do not fully know why — which is one of the more striking gaps in modern medicine given that it is administered millions of times a year with an excellent safety record. What

Question 5

What is a drug interaction, and which ones actually matter?

Accepted Answer

One substance changing how another behaves in the body — either how much of it reaches the bloodstream and for how long, or what effect it has once there. Most interactions are theoretical or minor;

Question 6

What is the placebo effect and how does it work?

Accepted Answer

The placebo effect is a genuine improvement in symptoms following a treatment that has no active therapeutic ingredient. It is not imagination, and it is not the same as people simply lying about

Question 7

Why do some medicines say "take with food"?

Accepted Answer

The instruction is not a formality — it addresses several genuinely different problems, and which one applies determines how strictly it matters. To reduce stomach irritation. Some drugs directly

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