Is Menthol and Camphor Safe During Pregnancy?

Topical menthol and camphor, at the concentrations found in common over-the-counter products, appear to be safe during pregnancy based on the available evidence. A systematic review of the ingredients found that doses capable of causing reproductive harm were hundreds to thousands of times greater than what the body absorbs from normal topical use. That said, the reassurance comes with real caveats: ingestion is a completely different risk category, concentration matters, and the research base is thinner than most people assume.

What the Research Actually Shows About Topical Use

The most directly relevant piece of evidence comes from a systematic review that examined the toxicology and teratology of menthol, camphor, and related ingredients as they appear in topical muscle-care products. The review concluded that while some of these ingredients can cause adverse reproductive effects at high systemic doses, those doses are hundreds to thousands of times greater than the amount that actually reaches the bloodstream through the skin when used at the recommended maximum of about 10 grams of product per day.¹

For camphor specifically, the review examined data from 168 pregnancies where camphor was used during the first trimester and 763 pregnancies where it was used at some point during the pregnancy. In both groups, the rate of birth defects was no higher than the background rate in the general population. Animal studies using oral doses of camphor far exceeding anything a person would encounter through topical use (up to 1,000 mg/kg/day in rats and up to 681 mg/kg/day in rabbits) also showed no increase in congenital abnormalities.¹

Those numbers are reassuring, but they deserve some context. The sample sizes are not enormous by modern clinical-trial standards. Most of the data comes from observational reports and animal studies rather than randomized controlled trials specifically designed to test safety in pregnancy. No researcher is going to run a placebo-controlled trial that deliberately exposes pregnant women to a potentially harmful substance, so the kind of gold-standard evidence that exists for, say, prenatal vitamins simply does not exist here. What we can say is that across the data we do have, topical use at normal doses has not been linked to fetal harm.

Why Ingestion Is a Completely Different Story

One thing the research makes very clear is that camphor can cross the human placenta when swallowed. That distinction between topical absorption and oral ingestion is crucial, because the amount of camphor that reaches the bloodstream through the skin is a tiny fraction of what gets absorbed through the gut.

Camphorated oil has a long history of poisoning cases, particularly in children. In Canada, preparations containing camphor concentrations of up to 20% were still being sold over the counter even after the United States restricted sale of camphorated oil at concentrations of 11% or greater. Case reports described children who suffered generalized seizures and respiratory depression after swallowing small amounts of these products.²

Those poisoning cases involved children, not pregnant women, but they illustrate the core point: camphor is a potent substance when it reaches the bloodstream in large quantities. Pregnancy adds another layer of concern because the compound can cross the placenta and potentially reach the fetus. Despite a number of reported camphor poisoning cases overall, no adverse fetal effects have been specifically documented to date.¹

Still, the absence of documented fetal harm from poisoning cases is not the same as proof of safety. It likely reflects the rarity of these events and the difficulty of following up on pregnancy outcomes after an acute poisoning episode. The practical takeaway is straightforward: never swallow products containing camphor or menthol, keep them out of reach of children in the home, and treat any accidental ingestion as a medical emergency.

How Menthol and Camphor Work on Your Body

Understanding what these substances do once they hit your skin or airways helps explain why the dose and route of exposure matter so much. Menthol produces its characteristic cooling sensation by activating a receptor called TRPM8, which is essentially a “cold sensor” on nerve cells. When menthol binds to this receptor, it triggers calcium release inside the cell, mimicking the feeling of cold without any actual temperature change.³

This same calcium-related mechanism is why peppermint oil, which is rich in menthol, acts as an antispasmodic on smooth muscle. It essentially blocks calcium channels, which relaxes the muscle. That is why menthol-containing products feel soothing on sore muscles and why peppermint tea can ease digestive cramping.³

Camphor works through a somewhat different pathway. It also activates certain temperature-sensitive receptors and produces a warm-then-cool sensation, but it has additional properties as a mild local anesthetic and counterirritant. When you rub a camphor-containing balm on your chest, the strong vapors stimulate nerve endings in the nasal passages, creating the sensation of breathing more freely even though the product does not actually reduce nasal congestion in a measurable way.

The reason topical exposure is so much safer than ingestion comes down to how much of the active ingredient makes it past the skin. Skin is a remarkably effective barrier. Only a small percentage of the camphor or menthol in a balm or cream penetrates through to the bloodstream. Compare that to oral ingestion, where the substance goes directly into the digestive system and gets absorbed rapidly and efficiently. That difference in bioavailability is why the systematic review found such a dramatic gap between the doses that cause harm and the doses that result from normal topical use.

Concentration and Product Type Make a Real Difference

Not all menthol and camphor products are created equal. The typical over-the-counter chest rub or muscle balm sold in most countries contains camphor at concentrations well below 11%, usually around 4 to 5%. Menthol concentrations in these products typically range from about 2 to 10%. At these levels, used as directed on the skin, the systemic exposure is minimal.

Problems arise when products contain higher concentrations or when they are used in ways the manufacturer did not intend. Camphorated oil historically contained camphor at concentrations of 20% and was sometimes mistaken for castor oil or other ingestible products. The U.S. restricted the sale of camphorated oil at concentrations above 11%, but other countries have been slower to act.²

Essential oils are another category worth paying attention to. Pure camphor essential oil and pure peppermint essential oil are dramatically more concentrated than the diluted versions found in consumer products. A reference guide on essential oil safety notes that adverse reactions to essential oils can include a range of serious outcomes, from skin reactions and bronchial hyperreactivity to neurotoxicity and even pregnancy complications including abnormalities.⁴

The distinction between a dab of Vicks VapoRub on your chest and a few drops of undiluted camphor essential oil applied to your skin or added to a bath is significant. The former delivers a controlled, low dose through formulated concentrations. The latter can deliver a much higher and less predictable dose, especially if used liberally or in a hot bath where increased blood flow to the skin boosts absorption.

Common Pregnancy Scenarios Where These Ingredients Come Up

Pregnant women most often encounter menthol and camphor in a handful of familiar situations. Cold and flu season is probably the most common trigger. When you are pregnant and congested, the list of medications you can safely reach for shrinks dramatically, and many women turn to vapor rubs, menthol lozenges, or steam inhalation as alternatives to oral decongestants.

Muscle and joint pain is the other big one. Pregnancy places enormous strain on the lower back, hips, and legs, and topical analgesics containing menthol and camphor are a natural choice when you are trying to avoid oral painkillers. A review of pain management in pregnancy noted that evidence for nonpharmacological approaches is limited and their efficacy unclear, though they do appear to be primarily safe.⁵

Here is a rundown of common product types and what to keep in mind:

Chest rubs: Products like Vicks VapoRub contain camphor (around 4.8%), menthol (around 2.6%), and eucalyptus oil. Applied to the chest or throat in a thin layer, these fall well within the range that the available research suggests is safe.
Menthol cough drops: These deliver a small amount of menthol orally, but the doses per lozenge are low, typically a few milligrams. Occasional use is generally considered acceptable, though sucking on them constantly throughout the day increases total exposure.
Muscle balms: Products like Tiger Balm or Biofreeze contain varying concentrations of menthol and sometimes camphor. Check the label for percentages and stick to the recommended amount.
Pure essential oils: Undiluted camphor or peppermint essential oils are far more concentrated and carry greater risk. Avoid applying them directly to the skin during pregnancy, and if you use them in a diffuser, keep sessions short and the room ventilated.

Menthol, Camphor, and Newborns With G-6-PD Deficiency

One important safety concern that most pregnancy guides overlook involves what happens after the baby is born. A controlled study examined the effects of menthol- and camphor-containing powders on 60 newborns who had glucose-6-phosphate dehydrogenase (G-6-PD) deficiency, a common inherited enzyme condition. Half of the babies had their umbilical cords dressed daily with the powder, while the other half served as controls. The treated babies developed significantly worse jaundice than the untreated group.⁶

The researchers concluded that menthol- and camphor-containing commercial products should not be used on newborns, especially in communities where G-6-PD deficiency is common. G-6-PD deficiency affects hundreds of millions of people worldwide, with particularly high prevalence in parts of Africa, the Mediterranean, the Middle East, and Southeast Asia. In babies with this condition, exposure to certain chemicals can trigger the breakdown of red blood cells, leading to jaundice that can become severe if untreated.

This finding is relevant to pregnancy in a broader sense: if you are from a population where G-6-PD deficiency is common, or if your partner is, your newborn may carry the trait. Avoiding menthol and camphor products on the baby’s skin in the first weeks of life is a straightforward precaution. This does not mean that your own topical use of these products during pregnancy poses a risk to the fetus through the same mechanism, but it is worth knowing about before your baby arrives.

Herbal Teas and Dietary Supplements Are a Separate Question

Many pregnant women drink peppermint tea to ease nausea or digestive discomfort, and this is one of the more common ways menthol enters the body orally during pregnancy. Peppermint tea is generally considered safe in moderate amounts, but the broader category of herbal teas during pregnancy deserves caution. A review of commonly used herbal teas during pregnancy emphasized that the rapidly developing fetus is particularly vulnerable to adverse effects from substances that might be harmless to an adult, and that many herbs marketed as teas have not been adequately studied for safety in pregnancy.⁷

The dose of menthol in a cup of peppermint tea is modest compared to a menthol cough drop or a chest rub, and occasional consumption is unlikely to be problematic. Where things get murkier is with concentrated peppermint oil capsules sold as dietary supplements for irritable bowel syndrome or other digestive issues. These capsules deliver a much higher bolus of menthol to the gut than a cup of tea does, and their safety during pregnancy has not been well studied. If you are using peppermint oil supplements, talk to your provider about whether to continue them during pregnancy.

Camphor does not typically show up in teas or dietary supplements in Western markets, but in some traditional medicine systems, camphor is taken orally in small amounts or added to home remedies. This is the kind of use that carries real risk given camphor’s ability to cross the placenta and its known toxicity at even moderate oral doses.

What Your Provider Likely Thinks About All This

Most obstetricians and midwives will tell you that occasional topical use of standard menthol and camphor products is fine during pregnancy. This is consistent with the available evidence: no signal of harm at normal topical doses, a large margin between those doses and the levels that cause problems in animal studies, and no documented cases of fetal harm from topical use in humans.

Where providers tend to draw the line is at heavy, frequent, or unconventional use. Applying a thick layer of camphor-containing balm multiple times a day, using undiluted essential oils on the skin, adding camphor to a hot bath, or ingesting camphor in any form would all raise concern. The basic principle that applies to most substances during pregnancy holds here too: use the lowest effective dose for the shortest period necessary.

If you are dealing with severe muscle pain or persistent congestion that makes you want to reach for these products multiple times a day, that is probably a conversation worth having with your provider. Not because the products themselves are dangerous at normal use, but because they may be able to suggest more effective approaches. Physical therapy, warm compresses, acetaminophen (which has a long safety record in pregnancy for short-term use), and saline nasal rinses may provide better relief than repeated applications of menthol rubs.

The Evidence Gap Nobody Talks About

The honest truth about menthol and camphor safety in pregnancy is that the evidence base is remarkably thin for substances used by millions of pregnant women every year. The systematic review that provides the most reassuring data covered a total of about 930 pregnancies with camphor exposure, which sounds decent until you realize that major drug safety studies in pregnancy routinely track tens of thousands of exposures. For menthol specifically, the pregnancy-specific human data is even sparser.

This does not mean these substances are unsafe. It means they occupy the large gray zone of “probably fine based on what we know, but we don’t know as much as we’d like.” That gray zone includes a huge number of everyday exposures during pregnancy, from household cleaning products to cosmetics to food additives. Regulatory agencies have generally not flagged topical menthol or camphor at standard concentrations as requiring pregnancy warnings, which reflects their assessment that the risk is low.

Researchers face a fundamental difficulty studying substances like these. Camphor and menthol are found in so many consumer products that isolating their effects from everything else a pregnant woman is exposed to is nearly impossible in an observational study. And running a randomized trial where you deliberately give a potentially harmful substance to pregnant women is ethically off the table. So we are left with animal data, case reports from accidental poisonings, and retrospective reviews of pregnancies where exposure happened to be documented. The consistency of the finding across these imperfect data sources, showing no signal of harm at typical topical doses, is what gives researchers and clinicians reasonable confidence.

1
PubMed Central. Toxicology and teratology of the active ingredients of professional therapy MuscleCare products during pregnancy and lactation: a systematic review – Section: Camphor
2
PubMed Central. Camphorated oil: still endangering the lives of Canadian children
3
PubMed Central. Evaluation of mint efficacy regarding dysmenorrhea in comparison with mefenamic acid: A double blinded randomized crossover study – Section: Discussion
4
ScienceDirect. Essential Oil Safety: A Guide for Health Care Professionals
5
PubMed Central. Pain Management in Pregnancy: Multimodal Approaches
6
PubMed. The risk of jaundice in glucose-6-phosphate dehydrogenase deficient babies exposed to menthol
7
PubMed Central. Frequently Used Herbal Teas During Pregnancy – Short Update