Can You Take Codeine While Pregnant?

Codeine is not considered safe during pregnancy by most medical guidelines, though it is sometimes prescribed at low doses for short periods when no adequate alternative exists. The drug crosses the placenta, its active metabolite morphine reaches fetal tissue, and the risks shift depending on the trimester, the dose, and the mother’s individual genetics. For a question that sounds like it should have a simple yes-or-no answer, the reality involves more moving parts than most people expect.

Codeine Crosses the Placenta

Codeine is a prodrug, meaning it does relatively little on its own. Your liver converts it into morphine via an enzyme called CYP2D6, and morphine is what actually suppresses pain. The problem for pregnancy is that this conversion does not stay confined to the mother’s body. Research using animal models has confirmed that codeine and all of its metabolites, including morphine, penetrate the placenta and reach fetal tissue.¹ In other words, when a pregnant person takes codeine, the fetus is exposed to morphine too.

What makes this exposure unpredictable is that pregnancy itself changes how the body processes codeine. CYP2D6 activity rises substantially as pregnancy progresses. One study measuring CYP2D6 activity across trimesters found that enzyme activity climbed by about 26% in the second trimester and nearly 48% by late pregnancy, compared to the postpartum baseline.² More enzyme activity means more codeine gets converted to morphine, which in turn means more morphine is available to cross the placenta. This is one of several reasons that a dose considered safe in a non-pregnant adult can produce different, and potentially higher, fetal exposure during pregnancy.

First Trimester and Birth Defect Risks

The first trimester is when organs are forming, and it is the window researchers focus on most when evaluating whether a medication causes structural birth defects. The evidence on codeine in this period is mixed, which is part of what makes counseling so difficult.

A large Norwegian cohort study comparing codeine-exposed pregnancies to unexposed ones found no significant increase in the overall rate of congenital malformations.³ That study, based on several thousand codeine-exposed pregnancies, was reassuring on the surface. But other research has identified specific concerns. A 2024 systematic review and meta-analysis looking at first-trimester opioid exposure found a raised risk for atrial septal defects (a type of heart defect) specifically with codeine, along with elevated but not statistically firm signals for cleft palate and gastrointestinal malformations with opioids more broadly.⁴

A separate cohort study found a more striking signal: the risk of spina bifida among codeine-exposed pregnancies was roughly four times higher than in unexposed pregnancies, and this association held up even after additional statistical adjustments.⁵ Spina bifida is a neural tube defect, and while the absolute number of cases in any study is small (because it is a rare condition), a fourfold increase in risk is the kind of finding that gets attention from clinicians. The evidence is far from settled, but these results are enough that most guidelines recommend avoiding codeine in the first trimester unless there is a compelling medical reason.

Risks in Later Pregnancy

The concern shifts in the second and third trimesters. Organ formation is largely complete by this point, so the worry is less about structural defects and more about complications with the pregnancy itself and what happens to the baby at delivery.

A large population-based cohort study found modestly increased risks of placental abruption and preterm birth with opioid exposure during pregnancy, and codeine specifically was associated with both. The risk increases were not dramatic in absolute terms, but they were consistent and statistically meaningful.⁶ Another study reported that first- and second-trimester codeine exposure was linked to a higher risk of preterm birth, along with a small increase in the rate of babies born smaller than expected.⁷

Importantly, these studies are observational. Women taking codeine during pregnancy often have underlying pain conditions, and pain itself, along with the stress and inflammation that go with it, may independently affect pregnancy outcomes. Researchers try to account for this, but it is difficult to fully disentangle the effect of the drug from the effect of the condition it is treating.

Neonatal Withdrawal After Delivery

One of the most concrete risks of codeine use late in pregnancy is neonatal withdrawal, sometimes called neonatal abstinence syndrome. When a baby has been exposed to opioids in the womb for a sustained period, the baby’s body can become physically dependent. After delivery, when the supply stops, withdrawal symptoms appear. These can include irritability, tremors, feeding difficulties, high-pitched crying, and in more severe cases, seizures.

Case reports have documented neonatal withdrawal syndrome specifically caused by codeine-containing preparations taken during pregnancy, including over-the-counter headache remedies and cough syrups.⁸ This is not limited to heavy or prolonged use; even therapeutic doses taken regularly in the final weeks of pregnancy can trigger it.⁹ The key factor is consistency of exposure in the weeks before delivery. A single dose is unlikely to cause withdrawal, but daily or near-daily use in the third trimester puts the newborn at real risk.

Why Your Genetics Matter More Than Usual

Codeine’s conversion to morphine by the CYP2D6 enzyme is not the same in everyone. Some people are “poor metabolizers,” meaning they produce very little morphine from codeine and get minimal pain relief. Others are “ultrarapid metabolizers,” producing much more morphine than average from the same dose. In the general population, this variation mostly affects whether the drug works well for you or whether you get more side effects than expected.

During pregnancy, this variation has higher stakes. Modeling research has found that in mothers who are ultrarapid metabolizers, fetal morphine exposure was about 1.8 times higher than in mothers with normal metabolism.¹⁰ That is a meaningful jump, and it happens without the mother necessarily realizing she is producing an unusual amount of morphine. It also means that the same codeine dose can result in very different fetal exposures depending on the mother’s genetic profile, making general dose recommendations unreliable for this particular drug.

The concern about CYP2D6 status has driven some researchers to call for pharmacogenetic testing before prescribing codeine to pregnant patients, though this is not yet standard practice in most healthcare settings.¹¹ Without testing, neither the patient nor the prescriber knows whether the fetus is being exposed to a modest or an outsized amount of morphine.

What If You Took Codeine Before Knowing You Were Pregnant

This is among the most common real-world scenarios. More than half of pregnancies are unplanned, which means a large number of first-trimester opioid exposures happen before the mother even confirms the pregnancy. A woman might take codeine for a headache, a dental procedure, or a cough without having any reason to think she could be pregnant.

If this applies to you, the data is more reassuring than alarming. The large Norwegian cohort study that found no overall increase in malformation rates included many women who used codeine around the time of conception or in early pregnancy.³ While specific risks like the spina bifida and heart defect signals cannot be ignored, the absolute risk of any individual defect remains small. Clinical guidance emphasizes stopping opioid use once pregnancy is recognized, seeking alternative pain management, and using the lowest effective dose if opioid treatment genuinely needs to continue. Detailed fetal imaging later in pregnancy can also screen for the kinds of structural issues flagged in the research.

What Doctors Typically Recommend Instead

When a pregnant person has pain that needs treatment, the starting point in most clinical guidelines is acetaminophen (paracetamol). It has the longest track record in pregnancy and, while not entirely without controversy, is broadly regarded as the safest first-line option for mild to moderate pain. Non-drug approaches such as physical therapy, heat application, and rest are also standard recommendations before moving to stronger medications.

When those options are not enough, the decision gets harder. Nonsteroidal anti-inflammatory drugs like ibuprofen are generally avoided in the third trimester because they can cause problems with fetal blood vessels, though they may be used cautiously earlier in pregnancy. Codeine and other opioids occupy an awkward middle ground: they are not banned outright, but they are reserved for situations where the pain is severe enough that the benefits of treatment outweigh the risks of fetal exposure. The general principle is the lowest effective dose for the shortest possible time.

In practice, some conditions, like kidney stones or severe migraine, genuinely require stronger pain control than acetaminophen can provide. In these situations, a short course of a low-dose opioid may be prescribed, and codeine has historically been among the ones chosen because of its relative familiarity and wide availability. But that familiarity can also be a trap. Because codeine is available over the counter in some countries as a component of cough syrups and combination painkillers, some pregnant people take it without realizing it warrants the same caution as a prescription opioid.

Long-Term Developmental Outcomes

Most of the research on codeine in pregnancy focuses on birth defects and neonatal complications, which are the most visible and immediate consequences. Less attention has been given to whether prenatal opioid exposure affects how children develop over time. A study that used teacher assessments of kindergarteners found that among children who had been exposed to prescription opioids before birth, the overwhelming majority had been exposed to low-potency opioids, primarily codeine.¹² The study used a standardized tool to evaluate developmental vulnerability in areas like language, social competence, and physical health.

Research on this question is still thin, and most of it cannot cleanly separate the effects of opioid exposure from the effects of the mother’s pain condition, stress, or other health factors. The honest assessment is that we do not know with confidence whether brief, low-dose codeine exposure in pregnancy has any lasting effect on child development. For longer or heavier exposures, the concern is more plausible, but the evidence is similarly limited. This is a gap in the research that is only now starting to get serious attention.

Codeine and Breastfeeding

The codeine conversation does not end at delivery. One of the most well-known cautionary cases in pharmacology involved a breastfed newborn who died of morphine poisoning after the mother was prescribed codeine for postpartum pain. The mother turned out to be an ultrarapid CYP2D6 metabolizer, producing far more morphine than typical. Her breast milk contained morphine concentrations vastly exceeding the normal range, and the newborn’s blood morphine levels were roughly 30 to 70 times higher than what is expected in breastfed infants whose mothers take codeine.¹³

That case was extreme, but it drove home the point that ultrarapid metabolizers can expose their newborns to dangerous morphine levels through breast milk.¹⁴ As a result, several regulatory agencies have since restricted or banned codeine use in breastfeeding mothers. For postpartum pain, alternatives like ibuprofen and acetaminophen are now strongly preferred. If codeine is used, guidance calls for the shortest possible course, careful monitoring of the infant for signs of sedation (unusual sleepiness, difficulty feeding, breathing changes), and prompt medical attention if those signs appear.

When Stopping Is Not Simple

For someone who has been taking codeine regularly before or during pregnancy, abruptly stopping can itself be a problem. Opioid withdrawal in a pregnant person is not just uncomfortable for the mother; it can trigger uterine contractions and, in some cases, has been associated with miscarriage or preterm labor. This is why medical guidelines generally advise against quitting opioids cold turkey during pregnancy. Instead, a supervised taper or, for more significant dependence, transition to a medication like methadone or buprenorphine is recommended.

This situation is different from occasional use for acute pain. If you took a few doses of codeine for a dental issue, you can simply stop. But if you have been taking codeine daily, whether by prescription or as part of an over-the-counter product, stopping should be managed with medical guidance. The goal is to get off the opioid without putting the pregnancy at risk from withdrawal effects, which sometimes means the safest short-term plan is a gradual reduction rather than immediate cessation.