Painkillers: Which One, How Much, and the Risks People Underestimate

Painkillers are the most commonly self-prescribed medicines in the world, and the most commonly misused. The risks are not exotic: kidney failure, stomach bleeding and liver damage from ordinary tablets taken for ordinary reasons.

Paracetamol

How it works: acts centrally; not anti-inflammatory.

Good for: headache, fever, mild to moderate pain, osteoarthritis as an adjunct, and pain in people who cannot take anti-inflammatories.

Dose: adults, 500 mg to 1 g every 4 to 6 hours, maximum 4 g in 24 hours, and less with low body weight, malnutrition, regular alcohol use or liver disease, where 2 to 3 g is a safer ceiling. Children are dosed by weight at 15 mg per kg per dose.

The real danger is that paracetamol is hidden inside many combination products: cold and flu sachets, cough syrups, migraine combinations and prescription pain combinations. Taking a cold remedy plus paracetamol tablets plus a combination painkiller can exceed the limit without the person realising. Read every label for paracetamol or acetaminophen.

Overdose causes liver failure, and crucially the person may feel well for the first 24 to 48 hours. There is an effective antidote, but only if given early. Any suspected overdose needs immediate hospital attention regardless of how the person looks.

NSAIDs

Ibuprofen, diclofenac, naproxen, aceclofenac, mefenamic acid, ketorolac, and aspirin at pain doses.

How they work: block prostaglandin production, reducing inflammation, pain and fever.

Good for: inflammatory and musculoskeletal pain, period pain, dental pain, gout, renal colic, headache and migraine.

The risks, which are substantially underestimated:

• Stomach: ulcers and gastrointestinal bleeding, which can occur without warning pain. Risk rises with age, previous ulcer, Helicobacter pylori, steroids, anticoagulants and alcohol
• Kidney: reduced blood flow to the kidneys. Taking NSAIDs while dehydrated, feverish, vomiting or on a diuretic plus an ACE inhibitor is a well-recognised route to acute kidney injury. This combination is sometimes called the triple whammy
• Cardiovascular: increased risk of heart attack and stroke with most NSAIDs, particularly at high dose and long duration. Diclofenac carries a comparatively higher risk
• Blood pressure: NSAIDs raise it and blunt antihypertensive drugs
• Asthma: a minority of asthmatics have severe reactions to NSAIDs
• Fluid retention and heart failure decompensation
• Pregnancy: avoid, especially after 20 weeks

Do not take NSAIDs if dengue is suspected or circulating, because of bleeding risk. Use paracetamol.

Use them sensibly: lowest effective dose, shortest duration, with food, one NSAID at a time never two, and with a stomach-protecting drug if you are at higher risk. Topical NSAID gels give useful local relief with far less systemic exposure and are under-used for joint and muscle pain.

Opioids

Tramadol, codeine, morphine, and combination products.

Appropriate for: severe acute pain, post-surgical pain, cancer pain, and palliative care.

Poor choices for: chronic non-cancer pain, headache and migraine, and routine back pain, where evidence of long-term benefit is weak and harms are substantial.

Risks: tolerance, dependence, constipation which is near-universal and needs a laxative from day one, sedation, respiratory depression, nausea, and in long-term use, paradoxically increased pain sensitivity. Tramadol additionally lowers the seizure threshold and interacts with antidepressants to cause serotonin syndrome.

Never combine opioids with alcohol or sedatives, and never drive while sedated.

Combination painkillers

Widely sold in India and often irrational. Fixed combinations of an NSAID with paracetamol, a muscle relaxant, a sedative or an opioid make it difficult to know what you are taking and how much, and raise the risk of exceeding paracetamol limits. Prefer single agents where possible.

Medication overuse headache

Taking any acute painkiller on more than 10 to 15 days a month for headache converts occasional headaches into daily ones. It is common and the only treatment is withdrawal.

Who should be especially careful

• Anyone with kidney disease, where most NSAIDs should be avoided entirely
• Liver disease, where paracetamol limits are lower
• Peptic ulcer history or current reflux
• Heart failure, uncontrolled hypertension, previous heart attack or stroke
• Asthma with known NSAID sensitivity
• People on blood thinners, steroids, lithium, methotrexate or diuretics
• Older adults, in whom all these risks are magnified
• Pregnancy and breastfeeding
• Children, where aspirin is contraindicated because of Reye’s syndrome

Non-drug pain management that works

Heat for muscle stiffness, cold for acute injury and swelling, graded activity and exercise which is the best evidence-based treatment for most chronic musculoskeletal pain, physiotherapy, weight loss for joint pain, good sleep, and addressing stress. These are not inferior substitutes; for chronic pain they outperform drugs.

Red flags, meaning get assessed rather than medicate

Severe sudden pain, pain with fever, chest pain, abdominal pain with vomiting, headache with neurological symptoms, pain that wakes you at night, pain with unexplained weight loss, and pain needing painkillers on most days for more than two weeks.

This is general information. Doses and choices depend on your kidney and liver function, other conditions and other medications, so confirm them with a doctor or pharmacist.