Codeine For Pain Relief: Essential Guide To Doses & Risks

Codeine is an

opioid painkiller

(analgesic) used to treat

mild-to-moderate pain

when simpler painkillers like paracetamol or ibuprofen are insufficient. Common side effects include nausea, constipation, drowsiness, and dry mouth.

About codeine

Codeine, also known as codeine phosphate, belongs to the opioid class of medications, sometimes referred to as opiates. It is primarily prescribed for

pain relief

and is available as tablets, oral liquid, or injections. Codeine works by binding to

opioid receptors

in the central nervous system (brain and spinal cord), reducing pain perception and emotional response to pain.

It’s particularly useful for pain not adequately managed by non-opioid analgesics. Codeine is also found in combination products like

co-codamol

(with paracetamol) or with ibuprofen, some available over-the-counter in low doses. For detailed information on co-codamol, refer to specific leaflets.

Forms and Uses of Codeine

Type of Medicine	Used For	Available As	Also Called
Opioid painkiller (analgesic)	Pain relief (mild-moderate)	Tablets, oral liquid, injection	Codeine phosphate

Codeine is FDA-approved for mild-to-moderate pain, including acute and chronic cases like cancer pain, though its use in non-cancer chronic pain is debated. It is also used for cough suppression by decreasing brain activity that triggers coughing.

Importantly, codeine’s pain-relieving effect relies on its conversion to

morphine

via the liver enzyme CYP2D6. Variability in metabolism means some people (ultra-rapid metabolizers) convert it too quickly, risking morphine overdose and respiratory depression.

Before taking codeine

Always consult a healthcare professional before starting codeine, especially if you have certain conditions or take other medications.

• Do not take codeine if: You are allergic to it, have acute alcohol intoxication, head injury, or increased intracranial pressure.
• Avoid in children under 12 years, or under 18 post-tonsillectomy/adenoidectomy due to respiratory risks.
• Caution in respiratory depression, asthma, COPD, severe hepatic/renal impairment, hypothyroidism, adrenal insufficiency, or prostatic hypertrophy.
• Inform your doctor if you have gallstones, bile duct issues, chronic constipation (>1 week), inflammatory bowel disease, myasthenia gravis, recent head injury, or history of drug/alcohol dependence.
• Pregnancy and breastfeeding: Use only if benefits outweigh risks; codeine passes into breast milk and can cause infant sedation or apnea.
• Check for interactions with MAOIs, other opioids, sedatives, antidepressants, or anticholinergics.

Ultra-rapid CYP2D6 metabolizers should avoid codeine due to high morphine levels. Genetic testing may be recommended in at-risk populations.

How to take codeine

Follow your doctor’s or pharmacist’s instructions precisely. The typical adult dose for pain is

30-60 mg every 4 hours as needed

, not exceeding

240 mg daily

.

• Different tablet strengths exist (15 mg, 30 mg, 60 mg); check the label.
• For cough, doses are lower, often in syrup form.
• Take with food or milk to reduce nausea.
• Swallow tablets whole with water; do not crush or chew.
• In children >12 years, use only for acute moderate pain unresponsive to paracetamol/ibuprofen, at the lowest effective dose for shortest time.

Dose adjustments may be needed for elderly, hepatic/renal impairment, or obesity. Do not exceed recommended doses to avoid overdose risks like respiratory depression.

Getting the most from your treatment

Codeine is for

short-term use

to minimize tolerance, dependence, and withdrawal.

• Tolerance: Body adapts over time, reducing effectiveness; avoid long-term use.
• Withdrawal: Stopping abruptly after prolonged use may cause restlessness, irritability, sweating, or flu-like symptoms. Taper dose gradually under medical supervision.
• Combine with non-drug measures: physiotherapy, heat/cold packs, rest.
• Inform surgeons/dentists of codeine use before procedures.
• Check OTC medicines for codeine to avoid overdose.
• Alcohol worsens sedation and respiratory depression; avoid.
• Codeine impairs alertness; do not drive or operate machinery until effects are known.

For ongoing pain, reassess with your doctor; alternatives like stronger opioids may be considered.

Can codeine cause problems?

Common side effects affect >1 in 10 people:

constipation

,

nausea/vomiting

,

drowsiness

,

dizziness

,

dry mouth

.

Common and Serious Side Effects

Frequency	Side Effects	Management
Common (>1/10)	Constipation, nausea, drowsiness, dizziness, dry mouth	Laxatives, antiemetics, hydration, sugar-free lozenges
Less common	Vertigo, confusion (elderly), itching, sweating, low blood pressure	Monitor, dose adjust
Serious (seek help)	Respiratory depression, severe allergy (rash, swelling), hallucinations, seizures	Emergency care
Overdose signs	Pinned pupils, slow breathing, coma	Naloxone antidote

Paradoxical effects like restlessness or worsened pain can occur. Long-term: dependence, hormonal disruptions (low testosterone). Report persistent issues to your doctor.

In children, watch for slow/shallow breathing, extreme sleepiness, confusion—stop and seek help.

How to store codeine

Store below 25°C in original packaging, away from light and moisture. Keep out of reach of children. Do not use after expiry date. Dispose of unused medicine via pharmacy take-back programs.

Important information about all medicines

• Never share prescription medicines.
• Read labels; take as directed.
• Inform doctors/pharmacists of all medicines/herbs.
• Check expiry dates.
• For missed doses, take if not near next; do not double.
• Overdose: Call emergency services immediately.

Frequently Asked Questions (FAQs)

Can children take codeine?

Restricted: Only children >12 years for acute moderate pain unresponsive to other analgesics, not post-tonsillectomy.

Is codeine addictive?

Yes, risk of dependence with prolonged use; use shortest duration possible.

Can I drink alcohol with codeine?

No, increases sedation and respiratory risks.

How long does codeine take to work?

30-60 minutes orally; peaks in 1-2 hours.

What if I forget a dose?

Take if time allows; skip if near next dose. Never double up.