The science behind CROWN Plus: what maximum cooling actually means

CROWN is our everyday roller. CROWN Plus is built for the hard days, when you want the cold deeper and longer. Those two goals pull against each other when menthol does all the work, because more menthol mostly gets you more burn.

CROWN Plus takes a different route: several coolants hitting the same cold receptor with different potencies and kinetics, in an oil base that stays on the skin. Same rule as the CROWN science article: if the evidence is a human trial, we tell you. If it is a mouse, a dish or a tradition, we tell you that too.

Why we built a hard-days roller

CROWN, our everyday roller, uses menthol at 7 percent with peppermint oil at 4 percent, camphor at 3 percent and borneol at 1.5 percent, all disclosed. The best-known menthol migraine trial used 10 percent, but menthol is a counterirritant and its burning quality climbs with concentration,^1,3 so CROWN pairs 7 percent menthol with camphor and borneol for a strong cold with a wide comfort margin. And CROWN isn't just about the cold: magnesium, Chuan Xiong and German chamomile round it out alongside the Bing Pian, which is why it's made for everyday use.

For the hard days we wanted something different: a deeper cold that lasts longer. The obvious route, 10 or 12 percent menthol, was one we did not want to take: at high concentrations menthol starts activating TRPA1, the receptor behind the sting of mustard oil.⁴ Colder, but also hotter. So we asked whether you could get a deeper, longer cold without leaning entirely on menthol. Flavor chemists have been doing that for decades.

How cold works: TRPM8 in one paragraph

Your skin has no "menthol receptor." It has TRPM8, an ion channel on cold-sensing nerve fibers that opens below roughly 25 degrees Celsius. Menthol opens the same channel chemically, so the nerve fires as if the skin were cold.⁸ That explains menthol's two limits: the sensation tracks how much menthol is at the receptor, so it fades as menthol evaporates or absorbs, and at high doses menthol spills onto TRPA1 and adds a burn.⁴ Any molecule that opens TRPM8 without touching TRPA1 is a cleaner coolant. Several exist.

The four coolants, graded honestly

We are not publishing percentages for CROWN Plus while a patent application is pending, but every ingredient is printed on the box in descending order of concentration, so you can see how the formula is weighted. Each entry carries an evidence grade: Human topical trial Mechanistic or in vitro Sensory panel or tradition

Menthol Human topical trial

Menthol is the anchor and the only coolant in any roller with a randomized human headache trial behind it. Borhani Haghighi and colleagues ran a double-blind crossover trial in 35 people with migraine without aura, comparing 10 percent menthol on the forehead and temples against 0.5 percent. The higher dose won on being pain-free at two hours (p = 0.001) and on nausea and light sensitivity.¹ Two caveats: it was small, and the comparator was low-dose menthol rather than an inert placebo. An open-label pilot of a 6 percent menthol gel reported 52 percent of participants improved at two hours, with no control group.² That is the human evidence: promising, small, thinner than the category admits. In CROWN Plus, menthol delivers the fast, sharp cold. It does not do all the work.

Menthyl lactate Mechanistic or in vitro

A menthol ester that activates mouse TRPM8 at a concentration very close to menthol (EC50 3.3 versus 4.1 micromolar).⁸ Formulators reach for it because it is reported to come on more slowly, last longer and feel milder. That reputation comes from supplier sensory panels and decades of flavor and cosmetic use, not from a peer-reviewed time-intensity study on skin; we have not found one. What is published is the receptor data and a fragrance-industry safety assessment.¹⁰

WS-3 (ethyl menthane carboxamide) Mechanistic or in vitro

A synthetic coolant from the 1970s, used in gum, toothpaste and topicals since, about as potent as menthol on TRPM8 (EC50 3.7 micromolar).⁸ In an 18-compound comparison by flavor chemists, WS-3 acted mainly on TRPM8 and not TRPA1, which is why it cools without menthol's hot edge; it also ranked above WS-23 in perceived cooling, though in the mouth, not on skin.⁹ Solid receptor data, industry sensory data, no headache trials.

WS-23 (methyl diisopropyl propionamide) Mechanistic or in vitro

The gentlest of the four: roughly ten times weaker than menthol at TRPM8 in vitro, essentially odorless, no burn.^8,9 Its job is the soft, long tail of cold after menthol has peaked. Regulators have reviewed it as an oral flavoring with no safety concern at those levels. Dermal data for WS-3 and WS-23 sit in supplier dossiers rather than the open literature, which is one reason we ask you to patch test before first use.

Why synthetic coolants, and why we name them

The wellness aisle treats "synthetic" as a red flag. We chose WS-3 and WS-23 anyway, for three reasons. Cleaner signal: they open TRPM8 without recruiting TRPA1, so more cold, not more burn.^4,9 No smell of their own: osmophobia, an aversion to odors during attacks, is one of the most consistent features of migraine, and coolants that add cold without adding more scent keep the mint and herbal blend from getting harsher mid-attack. Consistency: botanical oils vary lot to lot, a synthesized coolant does not.

In return we owe you transparency. Both WS coolants are printed on the box by their INCI names, Ethyl Menthane Carboxamide and Methyl Diisopropyl Propionamide, in their correct position in the ingredient order, and we are candid that their evidence is receptor pharmacology and industry sensory work, not clinical trials.

Bing Pian, Chuan Xiong and Bai Zhi

Bing Pian (borneol) Human topical trial, not headache

Borneol, "ice piece" in Mandarin, is the fifth cold-active ingredient and the bridge between the two traditions. It has one modern human trial worth the name: a randomized, double-blind, placebo-controlled study of 122 people with postoperative pain, in which topical borneol beat placebo on pain scores, with mouse work in the same paper pointing to TRPM8.⁵ A real trial, but postoperative pain, not headache, and the receptor story is contested: one group found borneol a weaker, temperature-dependent TRPM8 agonist,⁶ another found it mainly a TRPV3 agonist.⁷ Borneol is also a documented skin penetration enhancer,²² useful for holding cold on the skin and a reason not to use it on broken skin. In the United States it is approved as a flavoring, not a topical drug ingredient, so we make no drug claims for it.

Chuan Xiong (Ligusticum chuanxiong root oil) Tradition, plus oral trial data

The most-used herb in classical Chinese headache formulas. Its oil is dominated by phthalides such as ligustilide and senkyunolides.¹³ Meta-analyses do show Chuan Xiong-containing formulas reducing migraine frequency, duration and severity, including one of 19 randomized trials in 1,832 patients.^13,14 Every one of those trials used oral, multi-herb decoctions or granules, most were run in China with real concerns about quality and heterogeneity, and none tested the oil on skin. They speak to the herb's reputation, not to what it does in a roller.

The topical case is mechanistic and preclinical: ligustilide modulates TRPA1, the irritant receptor menthol overspills onto;¹⁵ senkyunolide I reduced nociceptive behavior in mice; the oil is a skin permeation enhancer in rat skin;¹⁶ and a rabbit study found slight irritation at high doses with no sensitization.¹⁷ The phthalides oxidize easily, which is why CROWN Plus ships in amber glass with vitamin E.

Bai Zhi (Angelica dahurica root oil) Mechanistic and animal

New to the CROWN family. Chinese medicine pairs Bai Zhi with Chuan Xiong for frontal headache so routinely that the pairing has its own pharmacokinetics: in rats, Bai Zhi raises exposure to Chuan Xiong's phthalides.²¹ Its furanocoumarins, chiefly imperatorin, modulate and then desensitize TRPV1, the heat and capsaicin receptor, and reduced nocifensive behavior in rats.¹⁹ Topical Angelica dahurica oil reduced ear swelling in mice,²⁰ and a 2022 review covers the wider pharmacology.¹⁸ None of that is human data.

Anyone allergic to plants in the carrot family (Apiaceae) should patch test first.

The quiet ingredients, briefly

Six ingredients are there for feel, scent and shelf life rather than cold, and we cover them in a separate article. In short: peppermint oil adds natural menthol and has the category's second real human trial, in which 10 percent peppermint oil in ethanol reduced tension-type headache intensity within 15 minutes in 41 people, with no significant difference from 1,000 mg acetaminophen¹¹ (tension-type headache, not migraine, and not the concentration in CROWN Plus). Eucalyptus and spearmint are aroma; 1,8-cineole is roughly 1,900 times weaker than menthol at TRPM8,⁸ and carvone does not cool at all. Bisabolol is a skin-conditioning agent with rodent nociception data and one negative human irritation study.^26,27 Roman chamomile adds a soft, apple-like note, and it is not the German chamomile used in the one topical chamomile migraine trial.²⁹ Tocopherol helps keep the terpene-rich oils fresh, which matters because oxidized terpenes are common contact allergens.²⁸

Why MCT oil, and why no magnesium

CROWN is hydroethanolic: alcohol and water carry the actives, which is what lets it hold 2 percent magnesium chloride. CROWN Plus is anhydrous, based on caprylic/capric triglyceride, the light, odorless fraction of coconut oil usually called MCT. That base shapes the rest of the formula.

No water means no preservatives. Microbes need water. An oil with no water phase is low risk under the cosmetic microbiology standard, so CROWN Plus needs no preservatives. CROWN gets there a different way, through its alcohol base, and both rollers are paraben-free.

Oil holds the cold longer. Ethanol flashes off fast, which gives CROWN its instant, dry hit.²³ Oil releases coolants over a longer window. MCT dissolves menthol-type actives well,²⁵ does not oxidize like unsaturated plant oils, stays liquid in a cold car, and was non-irritating and non-sensitizing in the human patch studies reviewed by the Cosmetic Ingredient Review panel.²⁵

No water also means no magnesium. Magnesium chloride is a salt and will not dissolve in oil; suspending it gives you a gritty roller. That is why magnesium stays in CROWN, where the water-and-alcohol base can carry it for the neck-and-shoulder use case, and CROWN Plus goes without.

CROWN Plus has no camphor either. Camphor gives CROWN its warm-then-cool signature, and CROWN Plus was designed to be cold without a warm phase.

Safety and how to use it

All of this is on the box, along with the full ingredient list in order, the lot number and the 24-month period-after-opening symbol. CROWN Plus is lavender-free, water-free, paraben-free, vegan and cruelty-free, and it is made for Cerebral Torque, based in New Jersey, at an ISO 9001 and GMPC certified facility.

Related reading: CROWN vs CROWN Plus: which cooling roller is right for you · The quiet ingredients in CROWN Plus · Strongest migraine roll-on: a buyer's guide · The science behind CROWN

These statements have not been evaluated by the FDA. This product is not intended to diagnose, treat, cure, or prevent any disease. For external use only. Avoid contact with eyes and mucous membranes. Not for use on children under 2. If you are pregnant, nursing, or have a medical condition, talk to your healthcare provider before use. Study descriptions in this article summarize published research on individual ingredients and are not claims about what CROWN Plus does. This article is for general information and is not medical advice.