Herb & supplement monograph

Calabash Chalk Drug Interactions, Uses, Safety & More

Medically reviewed by ·Updated July 2026
What is this page for?

First and foremost: how Calabash Chalk interacts with medications. The heart of this page is the interaction list — every drug Calabash Chalk is known to interact with, and how serious each one is.

But these pages have grown well beyond that into a full monograph — what Calabash Chalk is, what people use it for and how strong the evidence is, its safety and side effects, and answers to the questions we’re asked most — written and reviewed by the clinical staff at HelloPharmacist. It’s educational information from our licensed clinical databases, not medical advice, and we don’t sell or endorse products. Our editorial policy

Check Calabash Chalk against your medication

Add one medication
Calabash Chalk
+
Start typing any prescription or over-the-counter drug name.
Reviewed by licensed pharmacists Sourced from Natural Medicines
On this page
Interaction report

Drugs that interact with Calabash Chalk

0 medications have a known interaction with Calabash Chalk, graded by severity. Select any drug for the full evidence-based detail.

We don’t currently list any known drug interactions for Calabash Chalk. This doesn’t guarantee none exist — always confirm with your pharmacist before combining supplements with your medications.

Read The List Like a Pharmacist

What Severity, Likelihood & Evidence Mean

Severity — How Serious It Can Be

  • Major. Clinically significant; generally best avoided, or used only under direct professional supervision.
  • Moderate. May need monitoring, a dose adjustment, or separating the times you take each one.
  • Minor. Generally not clinically significant, but still worth noting and mentioning to your pharmacist.
  • No known interaction. Checked against our sources with nothing documented — not the same as proven safety.

Likelihood — How Well It’s Documented

  • Likely. Well-controlled human studies have demonstrated the likely existence of this interaction
  • Probable. Interaction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
  • Possible. Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists
  • Unlikely. Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans.

Where This Data Comes From

  • Interaction records are evidence-graded and sourced from the Natural Medicines database (TRC Healthcare), the same reference used by pharmacists and hospitals.
  • Each drug listed above links to the full report for that exact Calabash Chalk combination — clinical detail, likelihood, evidence level, and citations.
  • Content is reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.
Monograph

Calabash Chalk: Uses, Safety & Side Effects

Medically reviewed by · Reviewed July 2026 ·
The bottom line

Calabash chalk is a natural clay-like earth material eaten in some West African and other cultures, often during pregnancy to ease nausea or satisfy cravings. It is not a proven remedy, and testing has repeatedly found it contaminated with lead, arsenic, and other heavy metals, so health authorities warn against eating it. Avoid calabash chalk, especially during pregnancy and breastfeeding.

Part used
Natural clay-like mineral material (not a plant)
Common forms
Solid blocks, molded shapes, lumps, or powder for eating
People commonly use it for
  • Pregnancy cravings and morning sickness
  • Easing nausea
  • Cultural and traditional eating practice
  • Settling the stomach

Popular and traditional uses — not proof it works. See “Uses & effectiveness” below for the evidence.

Safety at a glance
OverallBest avoided

It is often contaminated with lead, arsenic, and other heavy metals and is not safe to eat.

PregnancyLikely Unsafe

When calabash chalk is used orally. Calabash chalk contains high levels of lead, arsenic, cadmium, and mercury. Animal data shows that calabash chalk...

Read the full pregnancy detail
BreastfeedingLikely Unsafe

When calabash chalk is used orally. Calabash chalk contains high levels of lead, arsenic, cadmium, and mercury. Animal data shows that calabash chalk...

Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center). Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Jump to a section

Overview

Calabash chalk is a natural clay-like or earth material that people eat in parts of West Africa (such as Nigeria) and among some communities elsewhere. It goes by many local names and is usually sold as molded blocks, lumps, or powder. It is not a herb or plant product — it is essentially a type of edible soil or clay.

It is most often eaten by women during pregnancy, both to satisfy strong cravings and in the belief that it helps with nausea or morning sickness. Eating clay or earth like this is a form of a practice called pica (a craving for non-food substances) or geophagy (eating earth).

Uses & effectiveness

People commonly use calabash chalk to ease nausea and vomiting in pregnancy, to satisfy cravings, and as part of long-standing cultural traditions. There is no good scientific evidence that it treats nausea or any medical condition.

What research and government testing have focused on is its safety, not its benefit. Because of contamination concerns, no health authority recommends calabash chalk for any use. Any perceived benefit is anecdotal and is outweighed by the known risks.

How it works

There is no proven medical mechanism behind calabash chalk. Some people believe the clay may absorb stomach acid or settle the stomach, similar to other clay-based remedies, but this has not been demonstrated for calabash chalk specifically.

Importantly, the main concern is not how it might "work" but what it contains. Laboratory analysis of calabash chalk samples has repeatedly found heavy metals such as lead and arsenic, which are toxic to the body and have no safe role in the diet.

Safety & precautions

Calabash chalk is not considered safe to eat. Food safety agencies in several countries have issued warnings because tested samples contained lead, arsenic, and sometimes other harmful metals. Lead in particular can damage the nervous system, kidneys, and blood, and is especially dangerous to unborn babies and young children.

Pregnancy: Avoid completely. Lead crosses the placenta and has been linked to developmental and neurological harm to the baby. Breastfeeding: Avoid, because toxic metals can pass into breast milk. Children should never be given calabash chalk.

If you have been eating calabash chalk, talk with your doctor or pharmacist. Ongoing cravings to eat earth or clay can also be a sign of an underlying issue, such as iron deficiency, that should be checked.

Side effects

Eating clay-like material can cause stomach upset, constipation, and intestinal blockage. Over time, contaminants can build up in the body.

The most serious concern is heavy metal poisoning. Long-term lead exposure can cause tiredness, belly pain, anemia, high blood pressure, kidney problems, and harm to the brain and nervous system. In children and unborn babies, lead can affect learning and development. Arsenic exposure carries its own long-term health risks.

Calabash Chalk: Reported Adverse Effects

Documented safety reports on Calabash Chalk from the evidence-graded Natural Medicines (TRC Healthcare) database, shown word-for-word from the licensed record.

Calabash chalk should not be consumed. It has been shown to contain high levels of lead, arsenic, cadmium, and mercury. Excessive and/or long-term exposure to these metals can increase the risk for serious adverse health effects, including neurological disorders and cancer.

  1. Reeuwijk NM, Klerx WNM, Kooijman M, Hoogenboom LAP, Rietjens IMCM, Martena MJ. Levels of lead, arsenic, mercury and cadmium in clays for oral use on the Dutch market and estimation of associated risks. Food Addit Contam Part A Chem Anal Control Expo Risk
  2. Nutraingredients. FSA issues warning against calabash chalk. UK Food Standards Agency Warning. October 2002. Available at: https://www.nutraingredients.com/Article/2002/10/16/FSA-issues-warning-against-calabash-chalk. Accessed October 23, 2020.
  3. Food Standards Agency. Importing food supplements and health foods. February 2018. Available at: https://www.food.gov.uk/business-guidance/importing-food-supplements-and-health-foods. Accessed October 23, 2020.
  4. NYC Health. Calabash chalk containing lead and arsenic. New York City Warning: https://www1.nyc.gov/assets/doh/downloads/pdf/lead/lead-calabash-chalk-faq.pdf. Accessed October 23, 2020.
DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.

Adverse-effects data: Natural Medicines, Therapeutic Research Center

Dosing

There is no safe or recommended dose of calabash chalk. Because it can contain toxic heavy metals, no amount is considered safe to eat. Health authorities advise not to use it at all.

If you are experiencing cravings to eat clay or chalk, or you have been using calabash chalk regularly, please speak with a pharmacist or doctor rather than continuing.

Pregnancy & Breastfeeding

Calabash Chalk & Pregnancy

Likely Unsafe

When calabash chalk is used orally. Calabash chalk contains high levels of lead, arsenic, cadmium, and mercury. Animal data shows that calabash chalk can inhibit uterine implantation, reduce maternal weight gain, and cause fetal changes in the brain, pregnancy resorption, abortion, and stillbirth.

  1. Reeuwijk NM, Klerx WNM, Kooijman M, Hoogenboom LAP, Rietjens IMCM, Martena MJ. Levels of lead, arsenic, mercury and cadmium in clays for oral use on the Dutch market and estimation of associated risks. Food Addit Contam Part A Chem Anal Control Expo Risk
  2. Nutraingredients. FSA issues warning against calabash chalk. UK Food Standards Agency Warning. October 2002. Available at: https://www.nutraingredients.com/Article/2002/10/16/FSA-issues-warning-against-calabash-chalk. Accessed October 23, 2020.
  3. Food Standards Agency. Importing food supplements and health foods. February 2018. Available at: https://www.food.gov.uk/business-guidance/importing-food-supplements-and-health-foods. Accessed October 23, 2020.
  4. NYC Health. Calabash chalk containing lead and arsenic. New York City Warning: https://www1.nyc.gov/assets/doh/downloads/pdf/lead/lead-calabash-chalk-faq.pdf. Accessed October 23, 2020.
  5. Aprioku JS, Ogwo-Ude EM. Gestational toxicity of calabash chalk (Nzu) in wistar rats. Int J Appl Basic Med Res. 2018;8(4):249-252.
  6. Ekanem TB, Ekong MB, Eluwa MA, Igiri AO, Osim EE. Maternal geophagy of calabash chalk on foetal cerebral cortex histomorphology. Malays J Med Sci. 2015;22(4):17-22.

Calabash Chalk & Breastfeeding

Likely Unsafe

When calabash chalk is used orally. Calabash chalk contains high levels of lead, arsenic, cadmium, and mercury. Animal data shows that calabash chalk can inhibit uterine implantation, reduce maternal weight gain, and cause fetal changes in the brain, pregnancy resorption, abortion, and stillbirth.

  1. Reeuwijk NM, Klerx WNM, Kooijman M, Hoogenboom LAP, Rietjens IMCM, Martena MJ. Levels of lead, arsenic, mercury and cadmium in clays for oral use on the Dutch market and estimation of associated risks. Food Addit Contam Part A Chem Anal Control Expo Risk
  2. Nutraingredients. FSA issues warning against calabash chalk. UK Food Standards Agency Warning. October 2002. Available at: https://www.nutraingredients.com/Article/2002/10/16/FSA-issues-warning-against-calabash-chalk. Accessed October 23, 2020.
  3. Food Standards Agency. Importing food supplements and health foods. February 2018. Available at: https://www.food.gov.uk/business-guidance/importing-food-supplements-and-health-foods. Accessed October 23, 2020.
  4. NYC Health. Calabash chalk containing lead and arsenic. New York City Warning: https://www1.nyc.gov/assets/doh/downloads/pdf/lead/lead-calabash-chalk-faq.pdf. Accessed October 23, 2020.
  5. Aprioku JS, Ogwo-Ude EM. Gestational toxicity of calabash chalk (Nzu) in wistar rats. Int J Appl Basic Med Res. 2018;8(4):249-252.
  6. Ekanem TB, Ekong MB, Eluwa MA, Igiri AO, Osim EE. Maternal geophagy of calabash chalk on foetal cerebral cortex histomorphology. Malays J Med Sci. 2015;22(4):17-22.
DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.

© 2026 Therapeutic Research Center

Pregnancy & lactation ratings: Natural Medicines, Therapeutic Research Center

References & further reading

The 6 references that drive our Calabash Chalk monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

  1. Aprioku JS, Ogwo-Ude EM. Gestational toxicity of calabash chalk (Nzu) in wistar rats. Int J Appl Basic Med Res. 2018;8(4):249-252. PubMed
  2. Ekanem TB, Ekong MB, Eluwa MA, Igiri AO, Osim EE. Maternal geophagy of calabash chalk on foetal cerebral cortex histomorphology. Malays J Med Sci. 2015;22(4):17-22.
  3. Reeuwijk NM, Klerx WNM, Kooijman M, Hoogenboom LAP, Rietjens IMCM, Martena MJ. Levels of lead, arsenic, mercury and cadmium in clays for oral use on the Dutch market and estimation of associated risks. Food Addit Contam Part A Chem Anal Control Expo Risk PubMed
  4. Nutraingredients. FSA issues warning against calabash chalk. UK Food Standards Agency Warning. October 2002. Available at: https://www.nutraingredients.com/Article/2002/10/16/FSA-issues-warning-against-calabash-chalk. Accessed October 23, 2020.
  5. Food Standards Agency. Importing food supplements and health foods. February 2018. Available at: https://www.food.gov.uk/business-guidance/importing-food-supplements-and-health-foods. Accessed October 23, 2020.
  6. NYC Health. Calabash chalk containing lead and arsenic. New York City Warning: https://www1.nyc.gov/assets/doh/downloads/pdf/lead/lead-calabash-chalk-faq.pdf. Accessed October 23, 2020.
Keep reading

This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

Pharmacist Counseling Corner

Calabash Chalk: Common Questions

Does Calabash Chalk interact with prescription medications?
We do not currently list any known drug interactions for Calabash Chalk. This does not guarantee that none exist, so always confirm with your pharmacist before combining it with your medications.
How are Calabash Chalk interactions rated?
Each interaction is graded major, moderate, or minor based on how clinically significant it is and the strength of the evidence behind it. Major interactions are the most serious and are best avoided, or used only under close professional supervision.
Is it safe to take Calabash Chalk with my medications?
It depends on the specific medication. Some combinations are fine, while others call for monitoring, timing changes, or should be avoided. Check your exact drug above and confirm with your pharmacist or doctor before starting, stopping, or changing anything.
Where does this Calabash Chalk interaction information come from?
Our interaction data is built on the Natural Medicines database — an evidence-graded reference for vitamins, herbs, and supplements — and is reviewed by licensed HelloPharmacist pharmacists, who may add clinical context.
What is Calabash Chalk?
It is a natural clay-like earth material eaten in some cultures, often by pregnant women for cravings or nausea. It is sold as blocks, lumps, or powder and is not a plant or herb.
Is Calabash Chalk safe to eat?
No. Testing has repeatedly found it contaminated with lead, arsenic, and other heavy metals, so health agencies warn against eating it.
Can I use Calabash Chalk during pregnancy?
No. Lead and other toxic metals can cross to the baby and harm development, so it should be avoided in pregnancy and while breastfeeding.
Why do some people crave eating Calabash Chalk?
Cravings for earth or clay (called pica) can happen in pregnancy or with nutritional issues like iron deficiency. If you have these cravings, it is worth getting checked by a doctor.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Where next
Supplement interaction checkerCheck any supplement or product against your medications Drug–drug interactionsCheck two or more of your medications against each other Browse medications A–ZEvery drug we’ve checked against herbs & supplements NDC & pricing lookupFind a drug’s NDCs, packaging and costs Ask a pharmacistFree, personal answer from our licensed team

Have a question about Calabash Chalk?

Our pharmacists answer your medication & supplement questions — free.

Ask a pharmacist