Drug & supplement interaction

Calabash Chalk + Phenylephrine

Phenylephrine brand names: Gilchew, AH Chew D, Gilchew IR, Sudafed PE, Biorphen.

No Known Interaction

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS · Updated July 2026 · Pair last verified Oct 4, 2026

The bottom line No known interaction

We found no known interaction between Calabash Chalk and Phenylephrine in our sources. Absence of a documented interaction is not the same as proven safety, and does not guarantee one does not exist. Do not start, stop, or change a medication or supplement based on this page; confirm with your pharmacist or doctor first.

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Interaction report

Calabash Chalk and Phenylephrine

We checked these two against our interaction database. Here is what we found.

No Known Interaction Found

We did not find a documented interaction between Phenylephrine and Calabash Chalk in our sources. This does not guarantee that the combination is completely free of risk — there is often limited research on supplements and herbal products, especially around drug interactions.

Worth understanding: our licensed dataset holds no drug-interaction record for Calabash Chalk at all — not against Phenylephrine, and not against any other medication we track. This verdict therefore rests on the absence of any recorded data, not on research that looked at this combination and found nothing. We cannot rule an interaction out.

If you decide to take both, the practical routine is simple: add one new thing at a time and note the date you started it. If the combination is going to disagree with you, it usually shows in the first days to a couple of weeks — and a start date turns “I’ve been feeling off” into something a pharmacist can actually work with. Do not stop a prescribed medicine on your own.

Always talk with your pharmacist or doctor before making changes to your medications or supplements, particularly if you take several medications or have an ongoing health condition.

Calabash Chalk safety at a glance

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

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 inhibi... Read the full pregnancy detail

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 inhibi... Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center) — the full detail is in the Special populations card below. Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Phenylephrine and Calabash Chalk? Ask Dr. Brian Staiger, PharmD, BCPS directly ›

What to actually watch for

What Phenylephrine’s Own FDA Label Lists

This is not an interaction — none of it involves Calabash Chalk. These are the most notable effects listed in the ADVERSE REACTIONS section of Phenylephrine’s own FDA label, for the medication by itself. Knowing the drug’s own list makes it easier to work out the likely cause if something new turns up while you take both. 3 of them are worth acting on rather than waiting out — marked below.

A slow heartbeat Worth acting on
Shortness of breath Worth acting on mentioned in 6.2% of FDA reports for Phenylephrine
Raised blood pressure Worth acting on
Blurred vision
Headache mentioned in 7.8% of FDA reports for Phenylephrine
Nausea mentioned in 7.6% of FDA reports for Phenylephrine
Vomiting

From the ADVERSE REACTIONS section of the FDA label for Phenylephrine. Read the label on DailyMed › Where a percentage is shown, it is the share of 221,388 voluntary FDA FAERS reports for Phenylephrine that mention that effect — a reporting proportion, not an incidence rate and not evidence the drug caused it. Calabash Chalk’s licensed record lists no adverse effects our clinical vocabulary could match, so there is no Calabash Chalk side to compare — that is a limit of the record, not a statement that Calabash Chalk has no side effects.

Special populations

Calabash Chalk in Pregnancy & Breastfeeding

Pregnancy And Lactation 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.

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

From our Q&A

Questions About Calabash Chalk or Phenylephrine

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Calabash Chalk or Phenylephrine, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Phenylephrine

This page covers Calabash Chalk only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Phenylephrine page lists 81 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Ephedra (major), Lithium (major), Peyote (major) and Rauvolfia Vomitoria (major).

By severity: 6 major · 60 moderate · 15 minor.

From our pharmacist’s overview on the Phenylephrine page

“If you take phenylephrine (Sudafed PE, Biorphen) for congestion, treat this list as one that needs real attention, since six of its 81 entries carry a major rating. Phenylephrine tightens blood vessels to clear your nose, and more than half of the interactions here come from stimulant ingredients, ephedra above all, that can push blood…”

Reviewed by 2 · Jul 18, 2026

Open the Phenylephrine interaction page

How much people look this up

Where Calabash Chalk and Phenylephrine Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Calabash Chalk

Steady interest

#1,268 of 1,452 supplements looked up here in the last 7 days

29 days ago today

Medication Phenylephrine

Top 25%

#668 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Where does our data come from?

Source: the Natural Medicines (TRC Healthcare) clinical database — the evidence-graded professional reference for herb & supplement interactions.
Citation library: 103,510 references behind our interaction content, 65,311 of them resolved to verified PubMed/DOI sources. See every Calabash Chalk reference on this page ↓
Freshness: we automatically re-check this combination every week — this pair was last verified October 4, 2026. The Calabash Chalk and Phenylephrine records this page draws on were last updated July 10, 2026.
What “no known interaction” means: no documented interaction in the sources above — not a guarantee of safety. Supplements are studied far less than prescription drugs, so we say exactly what the evidence supports, and nothing more.

Data structure & sourcing designed and verified by Dr. Brian Staiger, PharmD, BCPS.

Supplement

About Calabash Chalk

What is Calabash Chalk?

Pregnancy cravings and morning sickness
Easing nausea
Cultural and traditional eating practice
Settling the stomach

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.

Natural clay-like mineral material (not a plant) · Solid blocks, molded shapes, lumps, or powder for eating

An interaction check asks whether these two react with each other — it does not ask whether Calabash Chalk is a good idea for someone in your situation. Here is what our Calabash Chalk record says about it on its own.

Calabash Chalk: 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.

From our Calabash Chalk monograph — the full record covers uses, side effects and every documented interaction.

Read the full Calabash Chalk monograph & all interactions

Medication

About Phenylephrine

What Is Phenylephrine Used For?

Brand names: Gilchew, AH Chew D, Gilchew IR, Sudafed PE, Biorphen

Phenylephrine is used in several different products, and each one has its own use.

Injection (IV): raises blood pressure in adults with clinically important hypotension (low blood pressure) caused mainly by widened blood vessels. Some injections are labeled for anesthesia only. Others are labeled for anesthesia and septic shock.

Eye drops: Phenylephrine Hydrochloride Ophthalmic Solution is used to dilate the pupil.

Nasal products: temporarily relieve nasal and sinus congestion from the common cold, hay fever or other upper respiratory allergies.

Rectal suppositories: relieve itching, burning and discomfort from hemorrhoids and temporarily shrink hemorrhoidal tissue.

Most-Reported Side Effects for Phenylephrine

From FAERS, the FDA’s public side-effect reporting system (221,388 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Fatigue 20,609 reports

Headache 17,301 reports

Nausea 16,925 reports

Diarrhea 14,221 reports

Dyspnea 13,719 reports

See full Phenylephrine drug information

Keep checking

Other Drugs & Calabash Chalk

Browse every other medication we’ve checked against Calabash Chalk — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major

0Moderate

0Minor

2,829No known interaction

2,829 No interaction

No interaction 2,829 drugs checked — show the list

We also checked Calabash Chalk against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,829 medications checked with no known interaction — see the full Calabash Chalk list.

See the full Calabash Chalk interactions page

See every supplement checked against Phenylephrine, ranked by severity

Evidence & sources

Calabash Chalk References

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.

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
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.
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
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.
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.
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.

Medication overviews come from MedlinePlus (NIH); supplement label data from the NIH Dietary Supplement Label Database. Content is written and reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

Pharmacist Counseling Corner

Taking Calabash Chalk and Phenylephrine Together: Common Questions

Is it safe to take Calabash Chalk with Phenylephrine?

We do not list a known interaction between Calabash Chalk and Phenylephrine. That does not guarantee the combination is risk-free, so confirm with your pharmacist or doctor — especially if you take other medications or have a health condition.

Does Phenylephrine interact with any supplements?

Yes. Phenylephrine has documented interactions with 81 supplements in our database — Calabash Chalk is not one of them. The Phenylephrine interaction page linked on this page lists every one, ranked by severity.

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

Where next

Keep Exploring

Calabash Chalk monograph Uses, safety profile, and every drug interaction in one place Phenylephrine drug information The full plain-English guide to this medication Phenylephrine supplement interactions Every supplement checked against Phenylephrine, ranked by severity Supplement interaction checker Check any supplement or product against your medications Browse medications A–Z Every drug we’ve checked against herbs & supplements References The 6 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Phenylephrine and Calabash Chalk?

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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.