Will Codeine Show Up On A Drug Test?

Will Codeine Show Up on a Drug Test? UK Detection Times, Poppy Seeds and Prescriptions Explained

Will codeine show up on a drug test? Yes. Codeine is an opiate, and almost every multi-drug test includes an opiate line, usually labelled OPI or MOP, that picks it up. This applies whether the codeine came from a prescription, a pack of co-codamol from the pharmacy or a bottle of cough syrup.

What a rapid test cannot tell you is which opiate caused the result. Codeine, morphine, heroin and even a poppy seed bagel can all trigger the same line. This guide explains how codeine is detected, how long it stays in urine, saliva, blood and hair, how cut-off levels and poppy seeds affect results, and what to do if you take codeine and have a drug test coming up.

What is codeine?

Codeine is an opiate painkiller that occurs naturally in the opium poppy. It is used for mild to moderate pain, and less often for coughs and diarrhoea. In the UK it is most familiar as part of combination tablets, such as co-codamol (codeine with paracetamol) and codeine with ibuprofen.

Codeine works largely by turning into morphine. A liver enzyme called CYP2D6 converts a small proportion of each dose, roughly 5 to 10 per cent, into morphine, which provides much of the pain relief. This is why codeine use often leaves both codeine and morphine in a sample. Codeine can be habit-forming, and when misused it is sometimes mixed into fizzy drinks as "lean" or called "cody" on the street.

Is codeine legal in the UK?

Codeine is a Class B controlled drug under the Misuse of Drugs Act 1971, but how it is supplied depends on the strength:

• Over the counter: low-strength combination products containing up to 12.8 mg of codeine per tablet, such as co-codamol 8/500, can be bought from a pharmacy without a prescription. The packs warn that codeine can cause addiction and is for short-term use of up to 3 days.
• Prescription only: higher-strength co-codamol (15/500 and 30/500), codeine phosphate tablets and codeine linctus

Having prescription-strength codeine that was not prescribed to you, or supplying it to someone else, is an offence. For more on legal medicines that still affect safety at work, read What Drugs Are Legal in the UK in 2026?

Codeine and driving: codeine is not one of the drugs with its own legal blood limit. However, morphine is, with a limit of 80 micrograms per litre of blood, and the body turns some codeine into morphine. GOV.UK lists codeine among the opiate-based medicines you can drive after taking, provided it was prescribed to you, you followed your healthcare professional's advice, and it is not making you unfit to drive. Driving while impaired by any drug, including an over-the-counter painkiller, is still an offence. You can read more about drug-driving limits in our post on roadside drug tests.

Will codeine show up on a standard drug test?

Yes. The opiate test on rapid drug kits is designed to detect morphine, and codeine reacts with it strongly. A standard opiate line will therefore pick up:

• Codeine, including co-codamol and codeine cough syrups
• Morphine
• Heroin, which breaks down into morphine
• Dihydrocodeine, including co-dydramol
• Large amounts of poppy seeds

A rapid test cannot tell you which of these caused the result. Only a laboratory can identify the exact drug.

It also works the other way round. The opiate line does not reliably detect synthetic and semi-synthetic opioids such as oxycodone, tramadol, fentanyl, methadone or buprenorphine. Each of these needs its own test line. If you need to screen for a wider range of opioids, check the drug list carefully. Read What is Methadone? and What Are Nitazenes? for more on opioids that standard tests miss.

300 ng/ml or 2000 ng/ml: why the opiate cut-off matters

Rapid opiate tests are made at two common cut-off levels, and the difference matters a great deal for codeine:

• 300 ng/ml: the more sensitive level, used on most of our multi-drug cups, panels and the opiate test strip. It detects codeine for longer, but it is also more likely to react to poppy seeds and low over-the-counter doses.
• 2000 ng/ml: a higher threshold, used on our Recruitment 7 cup. It is less likely to be triggered by food or a single small dose, but it has a shorter detection window.

Neither level is "right" for every situation. Choose based on whether you need maximum sensitivity, for example in treatment monitoring, or fewer results that turn out to be innocent, for example in pre-employment screening.

Urine tests for codeine

Urine is the most common sample for codeine screening. Codeine and morphine are cleared mainly through the kidneys, so urine shows use over the past few days.

• Best for: pre-employment, random testing, treatment monitoring and home testing
• Strengths: longest window of the rapid tests, results in about 5 minutes, low cost per test
• Limitations: a non-negative opiate result cannot show whether it came from codeine, morphine, heroin or poppy seeds without a lab test

Saliva tests for codeine

Our oral fluid tests detect opiates, including codeine, at a cut-off of 40 ng/ml, typically for around 7 to 21 hours after use. Saliva reflects recent use, so it is useful when the question is whether someone may be affected now. Collection is done face to face, which makes the sample very hard to tamper with.

• Best for: post-incident testing, reasonable cause testing and on-site screening
• Strengths: non-invasive, observed collection, no toilet facilities needed
• Limitations: much shorter detection window than urine

Blood and hair tests

Blood and hair testing for codeine is carried out in a laboratory. Codeine has a half-life of around 3 hours, so a blood test usually only detects it for up to about 24 hours. Blood tests are mainly used in hospitals, in forensic cases and when police investigate drug driving. A hair test can show a pattern of opiate use over roughly 90 days, but it cannot show use in the last week or so, because hair takes time to grow above the scalp.

How long does codeine stay in your system?

The table below shows typical detection windows for codeine. The urine and saliva figures are based on the cut-off levels of the opiate tests we sell.

Test type	Opiate cut-off	Typical detection window
Saliva	40 ng/ml	Around 7 to 21 hours
Urine (standard)	300 ng/ml	Up to 3 to 5 days
Urine (higher cut-off)	2000 ng/ml	Up to 2 to 4 days
Blood (lab)	Lab dependent	Typically up to 24 hours
Hair (lab)	Lab dependent	Up to 90 days

After a single dose, codeine is usually detectable in urine for around 1 to 3 days. The upper end of these ranges is more likely after regular use or higher prescription doses. For full cut-off tables, see our urine drug detection times and saliva drug detection times.

What affects how long codeine can be detected?

• Dose and frequency: regular use or high prescription doses extend the detection window
• Genetics: the CYP2D6 enzyme varies a lot between people, which changes how much codeine is turned into morphine and how quickly
• Kidney function: codeine and morphine are cleared through the kidneys, so reduced kidney function prolongs detection
• Liver function: the liver breaks codeine down, so reduced liver function slows clearance
• Age: older adults often clear codeine more slowly
• Other medicines: some medicines that affect liver enzymes can change how codeine is processed
• Hydration: very dilute urine can push levels below the cut-off. This is why good tests check specific gravity.
• Test cut-off: a 300 ng/ml test detects codeine for longer than a 2000 ng/ml test

Can poppy seeds make you fail a drug test?

They can. Poppy seeds come from the same plant as codeine and morphine, and they can carry traces of both. Eating a lot of them, for example in poppy seed bagels, cakes or bread, can produce a non-negative opiate result on a rapid test for a short time afterwards. This is most likely on tests with a 300 ng/ml cut-off.

This is one of the main reasons a rapid opiate result should never be treated as proof of drug use on its own. If poppy seeds could be a factor, tell the person running the test, and make sure any non-negative result goes to a laboratory.

Other causes of an opiate result, and why lab confirmation matters

As well as codeine and poppy seeds, an opiate line can react to prescribed morphine and to dihydrocodeine. Some quinolone antibiotics have also been reported to cross-react with opiate screening tests. Rapid tests are screening tools, and a non-negative result is only a preliminary finding.

Laboratory confirmation by GC-MS or LC-MS measures codeine and morphine separately. The pattern of the two helps show whether the result is consistent with codeine, morphine, heroin or food. Heroin can only be confirmed by finding 6-MAM, a breakdown product unique to heroin. You can screen for this on site with our heroin 6-MAM test strips, which will not react to codeine.

Our Urine Lab Confirmation Pack covers opiates, comes with full chain of custody paperwork and is analysed by a UKAS accredited UK laboratory. Samples are usually processed within 5 working days of arriving at the lab. For regular workplace testing, the Split Key PRO cup keeps part of the sample sealed during screening, so the same sample can go to the lab.

How to read a codeine drug test result

Codeine does not have its own window on a rapid test. It shows up on the opiate line, labelled OPI or MOP (morphine). Each result has a control line (C) and a test line (T):

• Negative: both the C line and the T line appear. Any visible T line counts as negative, however faint.
• Non-negative (preliminary positive): only the C line appears, with no T line
• Invalid: no C line appears, so the test must be repeated with a new device

Read negative results at 5 minutes and allow up to 10 minutes for non-negative results to develop. A non-negative opiate result shows that an opiate was present above the cut-off. It does not show which opiate, or whether the person was impaired.

I take co-codamol or prescribed codeine. Will I fail a drug test?

Your opiate result may well be non-negative. That means the test is working correctly, not that you have done anything wrong. What matters is how it is handled:

• Tell the person running the test about all medicines you have taken recently, including over-the-counter painkillers and cough syrups, before you give a sample
• Keep the packaging, pharmacy label or prescription as evidence
• Ask for any non-negative result to be confirmed by a laboratory
• If you work in a safety-critical role, expect a conversation about fitness for work. Most drug and alcohol policies treat properly used medicines as a health matter rather than misconduct.

Do not stop taking prescribed medication to pass a test. Speak to your GP or pharmacist if you have concerns. If you find you need over-the-counter codeine for more than 3 days, talk to a pharmacist or GP as well.

Why do employers test for opiates like codeine?

Codeine can cause drowsiness, dizziness, blurred vision and slower reaction times. These effects are strongest when someone starts taking it, takes a higher dose, or combines it with alcohol or other sedatives. Because it is so easy to buy, codeine dependence can also develop without anyone noticing. Opiate testing is standard practice in these sectors:

• Construction
• Rail
• Transport and logistics
• Warehousing and manufacturing
• Healthcare and care settings

Testing helps employers keep people safe, apply their drug and alcohol policy fairly, and spot when someone may need support. Find out more on our workplace drug testing page, or browse our workplace drug tests.

Which codeine drug test should I use?

For a quick, low-cost check, the ALLTEST opiate urine test strip detects codeine at 300 ng/ml. To reduce positives from poppy seeds or a single over-the-counter dose, the Recruitment 7 cup uses the higher 2000 ng/ml opiate cut-off.

For broader workplace screening, the ALLTEST Workplace 13 cup covers opiates alongside 12 other drug groups. If you also need oxycodone, fentanyl, tramadol and nitazenes, the UKDrugTesting Ultimate 23 cup gives the widest opioid coverage in our range.

Test	Sample	Cut-off	Best for
Urine Drug Test Strips (Opiates)	Urine	300 ng/ml	Low-cost single drug checks at home or work
ALLTEST Recruitment Cup (7 drugs)	Urine	2000 ng/ml	Pre-employment screening with fewer poppy seed positives
ALLTEST Workplace Cup (13 drugs)	Urine	300 ng/ml	General workplace screening
Split Key PRO Workplace Cup (10 drugs)	Urine	300 ng/ml	Workplaces that want lab confirmation from the same sample
UKDrugTesting Ultimate Cup (23 drugs)	Urine	300 ng/ml	The widest opioid screen, including oxycodone, fentanyl, tramadol and nitazenes
Urine Drug Test Strips (Heroin 6-MAM)	Urine	10 ng/ml 6-MAM	Telling heroin use apart from codeine
ALLTEST Saliva Workplace Barrel (6 drugs)	Saliva	40 ng/ml	Recent use, post-incident and reasonable cause testing
Urine Lab Confirmation Pack	Urine (lab)	GC-MS	Confirming non-negative screening results

Frequently asked questions

Does co-codamol show up on a drug test?

Yes. Co-codamol contains codeine, which shows up on the opiate (OPI or MOP) line of a rapid drug test. The paracetamol in co-codamol is not tested for.

Will one co-codamol tablet show up on a drug test?

It can, particularly on a test with a 300 ng/ml opiate cut-off. Whether it does depends on the strength of the tablet, the time since it was taken, the person and the test used.

Does codeine show up as morphine?

On a rapid test, yes. Codeine and morphine both trigger the same opiate line, and part of every codeine dose turns into morphine in the body. A laboratory test reports codeine and morphine separately.

Should I stop taking codeine before a drug test?

No. If your codeine is prescribed or bought legitimately, keep taking it as directed and declare it before the test. Stopping suddenly after regular use can cause withdrawal symptoms, so speak to your GP or pharmacist about any concerns.

Does dihydrocodeine show up on a drug test?

Yes. Dihydrocodeine, found in co-dydramol and prescription painkillers, is closely related to codeine and usually triggers the opiate line.

Do police test for codeine at the roadside?

Roadside drug screening kits used by UK police test for cannabis and cocaine. If an officer believes a driver is impaired by any drug, they can carry out impairment tests and require a blood or urine sample at the police station.

Final thoughts

Codeine will show up on most drug tests because it triggers the opiate line found on nearly every multi-drug kit. It is typically detectable for up to around 21 hours in saliva, up to 3 to 5 days in urine at a 300 ng/ml cut-off, and up to 90 days in hair. However, a rapid opiate result cannot tell codeine apart from morphine, heroin or poppy seeds. Every non-negative result should be confirmed by an accredited laboratory before any decisions are made.

For employers, choosing the right opiate cut-off and following a clear confirmation process keeps testing fair. For individuals, declaring your medicines before the test is the simplest way to make sure a legitimate result is treated as one.

Need more choice? Visit our specialist site, UK Drug Testing

The kits above are the ones I recommend most often for codeine and other opiates. If you are building a full workplace testing programme, though, you may want a wider choice. Our specialist sister site, UK Drug Testing, stocks a much larger range for employers and testing professionals.

Over there you will find:

• Dual chamber split cup urine drug tests, plus saliva drug tests from 4 to 13 panels
• Breathalysers
• Workplace drug and alcohol testing starter packs
• Laboratory confirmation tests
• Online drug test training
• The free Drug Detection Window Calculator

Not sure which test is right for your workplace? Take the quick quiz for a recommendation, or speak to the UK Drug Testing team Monday to Friday, 8.30am to 5pm, on 01263 731 168.

Sources: Misuse of Drugs Act 1971, Schedule 2; GOV.UK: Drugs and driving, the law; The Drug Driving (Specified Limits) (England and Wales) Regulations 2014; Road Traffic Act 1988, section 5A; Drug Testing Kit urine and saliva detection tables.