Dihydrocodeine

Is dihydrocodeine safe?

Taken for a few days at the dose on the pack, dihydrocodeine is about as safe as codeine: it eases moderate pain, causes constipation and drowsiness, and rarely does serious harm. The trouble starts with longer use, higher doses and mixing. It is a full opioid that can cause addiction and stop breathing, and its reputation as a "weak" painkiller makes people careless with it. Deaths in England and Wales mentioning dihydrocodeine reached 133 in 2024, the highest since the Office for National Statistics series began in 1993, and that is before counting co-dydramol. We score it 38, between codeine (40) and tramadol (34).

How strong is dihydrocodeine?

Milligram for milligram it is close to codeine. The NHS Specialist Pharmacy Service multiplies a daily dihydrocodeine dose by 0.1 to get the equivalent dose of oral morphine, the same factor it uses for codeine and tramadol. Six 30 mg tablets a day, one every 4 hours, add up to 180 mg, roughly 18 mg of morphine.

The difference from codeine is in how it works. Codeine does little until the liver enzyme CYP2D6CYP450 enzymesA family of liver enzymes that break down many medicines. When another drug or supplement speeds them up or slows them down, drug levels change.More in the glossary turns it into morphine, which is why some children who convert it very quickly have died on normal doses. A 2001 study in volunteers found that dihydrocodeine's pain relief comes mainly from the drug itself rather than its morphine-like metabolite, so genetic differences matter less. The UK labels we checked carry no CYP2D6 warning. The US label for Trezix, a capsule of dihydrocodeine with acetaminophen and caffeine, copies codeine's warnings anyway and rules it out for children under 12. The UK label for Teva's 30 mg tablets allows children from age 4, at 0.5 to 1 mg per kilogram.

It is not a particularly good painkiller. A Cochrane review of single doses after surgery found that 8 people had to take 30 mg of dihydrocodeine for one extra person to get at least half their pain relieved, and that 400 mg of ibuprofen beat both 30 mg and 60 mg doses.

Deaths in England and Wales

These figures, from ONS death registrations, exclude co-dydramol, which added 11 more in 2024. Most of the deaths involve other drugs: only 38 of the 133 had no other substance on the certificate. For comparison, oxycodone, a much stronger opioid, was mentioned on 109.

A King's College London study of 2,071 deaths in England from 2001 to 2020 where dihydrocodeine was found at post-mortem or implicated in the death shows the pattern. The largest group involved tablets obtained illicitly, and those deaths were rising. 64.8% were accidental overdoses, and in deaths linked to misuse, 95.3% also involved other sedating drugs, mainly heroin and diazepam. When the dihydrocodeine had been bought over the counterOver-the-counterA medicine you can buy without a prescription, in a pharmacy or shop, with directions on the pack for safe use without a doctor.More in the glossary, 42.5% of deaths were suicides. The authors argue that calling it a "weak" opioid leads users to underestimate it.

Co-dydramol and the paracetamol trap

Co-dydramol combines 500 mg of paracetamol plus 7.46, 10, 20 or 30 mg of dihydrocodeine. All four strengths look alike from the paracetamol side, and the adult limit is the same 8 tablets in 24 hours. But 8 tablets of 30/500 deliver four times the dihydrocodeine of 8 tablets of 7.46/500. When the 20 mg and 30 mg versions arrived in 2018, the MHRA asked prescribers and pharmacists to write and check the strength every time.

The paracetamol is the other danger. Taking co-dydramol with a separate paracetamol, a cold and flu remedy or co-codamol is the usual way people go over the 4 g daily limit. The NHS says to call 111 after more than 8 tablets in 24 hours, and 999 if breathing becomes difficult.

Who should be careful

Talk to your doctor or pharmacist before taking dihydrocodeine if you:

• have asthma, COPD or sleep apnoea (it can release histamine, and labels say not to use it during an asthma attack)
• have liver or kidney disease, an underactive thyroid or a head injury
• take a benzodiazepine, sleeping pill, antidepressant, gabapentin or pregabalin, or drink most days
• have ever had a problem with alcohol, opioids or other drugs
• are pregnant or breastfeeding

If you bought co-dydramol, stop after 3 days and see a doctor if the pain continues. After weeks of regular use, do not stop suddenly; withdrawal brings anxiety, sweating, shaking and aches, and a taper is safer. Signs of overdose are pinpoint pupils, extreme sleepiness and slow or shallow breathing: call 999 and give naloxone if you have it. A low score does not mean you should stop a medicine you have been prescribed.

How we scored it

Track record (85) is the strongest factor, after more than a century of use, though with little modern trial evidence. Dependence (20) and regulatory warnings (15) match codeine, which has the same US schedule and UK pack rules. Overdose marginOverdose marginHow far a normal dose is from a harmful one. A wide margin means an accidental extra dose is unlikely to cause serious harm.More in the glossary (35) sits below codeine's because of the record 2024 death count and the misuse pattern in English post-mortem data. Interactions (30) and serious side effects (45) reflect a standard opioid profile with the added paracetamol risk of co-dydramol.