Pain & Anesthesia Medications

WHO Pain Ladder

A stepwise approach to pain management — start at the bottom and step up as needed.

The World Health Organization (WHO) developed a three-step analgesic ladder for managing pain. The principle is: match the drug to the pain level, and always use the least potent effective option first.

Step 1mild pain 1–3/10

Non-opioid ± adjuvant — Acetaminophen, NSAIDs (ibuprofen, naproxen)

Step 2moderate pain 4–6/10

Weak opioid ± non-opioid ± adjuvant — Tramadol, codeine, hydrocodone/acetaminophen

Step 3severe pain 7–10/10

Strong opioid ± non-opioid ± adjuvant — Morphine, fentanyl, hydromorphone, oxycodone

Opioid Analgesics

The most tested pain medication class — know the rules before giving any opioid.

Opioids bind to mu receptors in the CNS, altering pain perception. They are used for moderate-to-severe acute and chronic pain. All opioids are controlled substances (Schedule II = highest abuse potential).

Before Giving ANY Opioid — Assess

• Respiratory rate — hold if RR <12 breaths/min and notify provider
• Level of consciousness — sedation precedes respiratory depression. Increasing sedation is an early warning.
• Blood pressure — opioids cause hypotension (orthostatic)
• Pain level — document baseline pain score before and 30–60 min after administration
• Allergies — ask about true allergy vs side effects (nausea is a side effect, not an allergy)
• Other CNS depressants — benzos, alcohol, muscle relaxants, antihistamines all INCREASE respiratory depression risk
• Last dose — check when the last dose was given to avoid stacking

Opioid Comparison Chart

Know the relative potencies and routes — this helps you identify safe doses on the exam.

MorphinePO/IV/IM/SubQ/epidural

Standard — all opioids compared to this. Gold standard for severe pain. Histamine release → itching, hypotension. Avoid in renal failure (active metabolites accumulate). Used in MI for pain + reduces preload.

Hydromorphone (Dilaudid)PO/IV/SubQ

5–7× stronger than morphine. Used when morphine isn't tolerated. Less histamine release. HIGH potency → high overdose risk with dosing errors. Double-check doses carefully.

FentanylIV/transdermal/SL/nasal

50–100× stronger than morphine. Very fast onset IV (1–2 min). Patch: 72 hours, takes 12–24 hrs to reach full effect. Do NOT cut patches. Remove old patch before applying new one. Heat increases absorption (no heating pads over patches).

OxycodonePO

1.5× stronger than morphine PO. Often combined with acetaminophen (Percocet). Extended-release (OxyContin): do NOT crush, chew, or break (risk of dose dumping → overdose). High abuse potential.

HydrocodonePO

Similar to morphine PO. Often combined with acetaminophen (Vicodin/Norco). Monitor for acetaminophen toxicity in combination products (max 3–4 g/day total).

CodeinePO · weak opioid

Often combined with acetaminophen (Tylenol #3). Some patients are ultra-rapid metabolizers → increased toxicity. Avoid in children <12 (FDA black box warning).

Tramadol (Ultram)PO · weak opioid + SNRI

Lowers seizure threshold. Serotonin syndrome risk if combined with SSRIs/SNRIs/MAOIs. Less respiratory depression than strong opioids but still possible. Schedule IV.

Meperidine (Demerol)PO/IM/IV · largely AVOIDED

Active metabolite (normeperidine) causes seizures, especially with repeated doses or in renal impairment. Do NOT use with MAOIs (fatal interaction). Do NOT use in elderly.

Opioid Side Effects & Management

Every opioid causes these — know how to prevent and manage each one.

Constipation

#1 side effect. DOES NOT resolve with tolerance. Start a bowel regimen (docusate + senna) with the FIRST opioid dose. Increase fluids and fiber. Do NOT wait for the patient to become constipated.

Sedation

Precedes respiratory depression — increasing sedation is an early warning sign. Monitor sedation scale. Fall precautions. Bed alarm. Assist with ambulation.

Respiratory depression

Monitor RR, SpO₂. Hold if RR <12. Naloxone at bedside for high-risk patients. Avoid concurrent CNS depressants.

Nausea/Vomiting

Antiemetics (ondansetron). Position changes slowly. Usually improves with continued use (tolerance develops).

Urinary retention

Monitor I&O. Assess for bladder distension. May need straight catheterization.

Hypotension

Monitor BP. Rise slowly. Fall precautions. Ensure adequate hydration.

Pruritus (itching)

Histamine release (not a true allergy). Diphenhydramine (Benadryl). Cool compresses. Distinguish from true allergic reaction (hives, swelling, anaphylaxis).

Miosis

Pinpoint pupils = sign of opioid use/overdose. Not harmful itself but is an assessment finding.

Naloxone (Narcan)

The opioid antidote — know when to give it and what to expect after.

Key Facts

• Mechanism: Competitive opioid antagonist — displaces opioids from mu receptors and reverses ALL opioid effects (including pain relief)
• Onset: IV = 1–2 minutes, IM/SubQ = 3–5 minutes, intranasal = 3–5 minutes
• Duration: 30–90 minutes — SHORTER than most opioids. This means the patient can re-sedate after naloxone wears off.
• Indications: RR <12, unresponsive/difficult to arouse, suspected opioid overdose, pinpoint pupils with respiratory depression

Critical Nursing Actions After Giving Naloxone

• Continue monitoring — the opioid may outlast naloxone. Patient can re-sedate and stop breathing again. Monitor RR, LOC, and SpO₂ continuously for at least 1–2 hours after the last dose.
• Repeat doses may be needed every 2–3 minutes until respirations improve
• Titrate carefully — the goal is to restore respirations, NOT to fully reverse all pain relief. Give just enough to bring RR above 12.
• Expect withdrawal symptoms in opioid-dependent patients: agitation, tachycardia, diaphoresis, nausea/vomiting, pain, tremors. This is expected and not a reason to withhold naloxone if respiratory depression is present.

PCA (Patient-Controlled Analgesia) Pumps

The #1 rule: ONLY the patient presses the button.

How PCA Works

An IV pump programmed to deliver a preset dose of opioid when the patient pushes a button. The pump has a lockout interval (e.g., every 8–10 minutes) that prevents overdose. Some PCAs also have a continuous basal rate.

Key Nursing Considerations

• ONLY the patient may push the button — NEVER a family member, friend, or nurse. This is the safety mechanism: if the patient is too sedated, they can't push the button, which prevents overdose. This is called "PCA by proxy" and is a NEVER event.
• Teach the patient to push the button BEFORE pain becomes severe (stay ahead of pain)
• Monitor: RR, sedation level, pain score, total doses used, and site assessment
• Verify the PCA settings with another nurse (drug, concentration, dose, lockout interval, basal rate)
• Common PCA opioids: morphine, hydromorphone, fentanyl
• Naloxone should be readily available

NSAIDs (Non-Steroidal Anti-Inflammatory Drugs)

Anti-inflammatory + analgesic + antipyretic — but watch the stomach and kidneys.

NSAIDs inhibit cyclooxygenase (COX-1 and COX-2) enzymes → decrease prostaglandin production → reduce inflammation, pain, and fever.

Ibuprofen (Advil, Motrin)PO

Most common OTC NSAID. Take with food. Max 3,200 mg/day (prescription). Avoid in 3rd trimester pregnancy (closes ductus arteriosus).

Naproxen (Aleve)PO

Longer acting than ibuprofen (q12h vs q6-8h). Same GI/renal risks.

Ketorolac (Toradol)IV/IM/PO

Most potent NSAID. Used for acute pain (post-op). Limited to 5 days max (high GI bleed risk). Not for chronic use.

Aspirin (ASA)PO

Antiplatelet at low dose (81 mg). Analgesic/anti-inflammatory at higher doses. Do NOT give to children <19 with viral illness (Reye syndrome). Chew 325 mg during MI.

Celecoxib (Celebrex)PO · COX-2 selective

Less GI irritation but increased cardiovascular risk (MI, stroke). Contraindicated in sulfonamide allergy.

Key NSAID Side Effects & Warnings

• GI bleeding/ulceration — take with food and a full glass of water. Report black/tarry stools, abdominal pain.
• Renal impairment — NSAIDs reduce renal blood flow. Avoid in CKD patients. Monitor BUN/Cr.
• Increased bleeding risk — inhibit platelet aggregation. Hold before surgery (typically 7 days for aspirin, 3–5 days for others).
• Cardiovascular risk — long-term use increases risk of MI and stroke (especially COX-2 inhibitors)
• Allergic reactions — can trigger asthma in aspirin-sensitive patients ("aspirin triad": asthma, nasal polyps, aspirin sensitivity)

Acetaminophen (Tylenol)

Safe and effective — unless you exceed the dose limit.

• Analgesic and antipyretic — NO anti-inflammatory effect
• First-line for mild pain and fever
• Maximum dose: 3–4 g/day (3,000–4,000 mg) in healthy adults. Lower limit (2 g/day) in patients with liver disease, chronic alcohol use, or elderly.
• Hepatotoxicity is the #1 risk — leading cause of acute liver failure from drug overdose
• Found in MANY combination products (Vicodin, Percocet, NyQuil, cold meds) — patients may not realize they're taking acetaminophen from multiple sources → overdose risk. Always calculate TOTAL daily acetaminophen from ALL sources.
• Antidote: Acetylcysteine (Mucomyst/Acetadote) — most effective if given within 8–10 hours of overdose. Can be given PO or IV.
• Signs of toxicity: nausea, vomiting, RUQ pain, elevated liver enzymes (AST/ALT), jaundice (may not appear for 24–72 hours)
• Avoid alcohol with acetaminophen (additive liver damage)

Non-Opioid Adjuvant Analgesics

These drugs aren't primary analgesics, but they enhance pain control — especially for neuropathic pain.

Gabapentin (Neurontin)anticonvulsant

Neuropathic pain, phantom limb pain, fibromyalgia, post-herpetic neuralgia. Drowsiness, dizziness. Do NOT stop abruptly (seizure risk). Dose at bedtime if drowsiness is an issue. Reduce dose in renal impairment.

Pregabalin (Lyrica)anticonvulsant · Schedule V

Neuropathic pain, fibromyalgia, diabetic neuropathy. Similar to gabapentin but more potent. Dizziness, weight gain, peripheral edema.

Duloxetine (Cymbalta)SNRI antidepressant

Diabetic neuropathy, fibromyalgia, chronic musculoskeletal pain. Takes 2–4 weeks for pain benefit. Do NOT stop abruptly. Monitor for serotonin syndrome if combined with other serotonergic drugs.

Amitriptylinetricyclic antidepressant

Neuropathic pain, migraine prophylaxis. Used at LOW doses for pain. Anticholinergic effects. Sedating — give at bedtime. Avoid in elderly (Beers criteria).

Corticosteroids (dexamethasone)anti-inflammatory

Inflammation-related pain, spinal cord compression, cancer pain. Short-term use. Monitor glucose. Taper when discontinuing. GI protection.

Lidocaine patch (Lidoderm)local anesthetic topical

Localized neuropathic pain, post-herpetic neuralgia. Apply to intact skin only. 12 hours on, 12 hours off. Do not apply to broken or inflamed skin.

Capsaicin creamtopical analgesic

Arthritis pain, neuropathic pain. Burning sensation initially (decreases with continued use). Wash hands thoroughly after application. Avoid eyes/mucous membranes.

Local Anesthetics

Block nerve conduction at the site — patient stays awake.

Lidocaine

Most commonly used local anesthetic. Also used IV for ventricular arrhythmias. Toxicity signs: tinnitus, metallic taste, dizziness, tremors, seizures → cardiac arrest at high doses. Max dose with epinephrine: 7 mg/kg; without: 4.5 mg/kg.

Bupivacaine (Marcaine)

Longer-acting than lidocaine. Used for nerve blocks, epidurals, spinal anesthesia. Higher cardiotoxicity risk than lidocaine.

EMLA cream (lidocaine + prilocaine)

Topical anesthetic applied 60 minutes before needle procedures (IV starts, blood draws in children). Cover with occlusive dressing. Do NOT apply to broken skin.

• Local anesthetics are often combined with epinephrine — causes vasoconstriction → prolongs anesthetic effect and reduces bleeding at the site
• Do NOT use epinephrine in fingers, toes, ears, nose, or penis (end arteries — vasoconstriction can cause tissue necrosis)
• Monitor for allergic reactions (especially ester-type locals)
• Assess sensation return before allowing patient to eat (risk of biting cheek/tongue) or bear weight (risk of injury to numb area)

Conscious Sedation (Moderate Sedation)

Patient is sedated but responsive — respiratory monitoring is the priority.

Conscious sedation is used for procedures like endoscopy, colonoscopy, cardioversion, fracture reduction, and wound repair. The patient maintains protective reflexes and can respond to verbal commands.

Common Drugs Used

• Midazolam (Versed) — short-acting benzodiazepine. Causes amnesia (patients may not remember the procedure). Antidote: flumazenil.
• Fentanyl — rapid onset, short duration. Antidote: naloxone.
• Propofol (Diprivan) — rapid onset, rapid recovery. Causes respiratory depression and hypotension. Milky-white appearance. Contains egg lecithin and soybean oil — ask about egg and soy allergies. Must be administered by trained provider (not LPN scope in most states).

Nursing Responsibilities

• Continuous monitoring: SpO₂, respiratory rate, heart rate, BP, LOC
• Suction, oxygen, bag-valve mask, and emergency equipment at bedside
• Reversal agents immediately available: naloxone (opioids) + flumazenil (benzos)
• NPO before procedure (aspiration risk)
• Maintain IV access throughout and during recovery
• Discharge criteria: alert, stable vitals, able to swallow, pain controlled, responsible adult driver present

Epidural Analgesia

Used for surgical pain and labor — know the complications and the positioning.

An epidural catheter delivers analgesic (opioid and/or local anesthetic) into the epidural space of the spinal column. It provides excellent pain control with less sedation than IV opioids. Common in post-surgical pain management and labor/delivery.

Nursing Considerations

• Monitor respiratory rate closely — opioids in the epidural can migrate cephalad (toward the brain) and cause delayed respiratory depression (up to 24 hours after administration)
• Monitor BP — epidural anesthesia causes sympathetic blockade → vasodilation → hypotension. IV fluid bolus before placement helps prevent this.
• Assess motor and sensory function — check for appropriate level of numbness. If sensory block rises too high → notify provider (respiratory compromise risk)
• Monitor for urinary retention — common. May need catheterization.
• Assess the catheter site — check for leakage, displacement, redness, swelling, signs of infection
• Keep HOB elevated ≥30° to prevent cephalad migration of the drug
• Fall precautions — lower extremity weakness/numbness
• Do NOT give anticoagulants close to epidural insertion/removal (risk of epidural hematoma → spinal cord compression)

Complications to Watch For

• Hypotension — most common. Treat with IV fluids, ephedrine if severe.
• Respiratory depression — delayed (can occur hours later). Monitor RR closely.
• Post-dural puncture headache — if the dura is accidentally punctured. Worse when upright, better when lying flat. Treated with bed rest, fluids, caffeine, and possibly an epidural blood patch.
• Epidural hematoma/abscess — rare but serious. Signs: severe back pain, motor weakness, bowel/bladder dysfunction → neurosurgical emergency.
• Pruritus — common with epidural opioids. Treat with nalbuphine or low-dose naloxone.

Frequently Asked Questions

Common student questions on this topic.

Quick-Reference Cheatsheet

Every key point from this guide on a single printable page.