Green Oil Essence (綠油精) — Taiwan’s National Medicated Oil

In Taiwan, it is hard to find a household medicine box without that small green glass bottle. Open the roller or dropper top, and a sharp coolness shoots straight up the nose — that is Green Oil Essence (綠油精, Lǜ Yóu Jīng). It is not Hong Kong’s Wood Lock Oil, nor Singapore’s Tiger Balm. It is a thoroughly home-grown Taiwanese medicated oil that has accompanied at least three generations of Taiwanese from childhood. This guide covers the formula pharmacology, brand history, official indications, and safety contraindications of this “national medicated oil.”

1. Brand and History: From a Fengyuan Pharmacy to the National Medicine Box

Green Oil Essence is made by Hsin Wan Jen Chemical & Pharmaceutical Co., Ltd. (新萬仁化學製藥), headquartered in the Fengyuan District of Taichung. Founder Lin Tian-ru (林添如, 1917–1994) and his wife Lin Chen Xing-yuan started from a small post-war shop called “Rì Róng Táng Pharmacy” (around 1947), founded “Wan Jen Pharmaceutical Works” in 1953, and later expanded and renamed it “Hsin Wan Jen Pharmaceutical.” The company first found its footing with a 1953 stomach-and-bowel remedy (“Gold Cross”) and a 1958 cold medicine. But the product that truly carried the brand into every household — Green Oil Essence — was formally launched in 1964.

Half of Green Oil Essence’s place in the national memory belongs to its advertising jingle. The melody — “Lǜ Yóu Jīng, Lǜ Yóu Jīng, Daddy loves Green Oil Essence, big brother, big sister, little sister all love Green Oil Essence, fragrant and fresh Green Oil Essence” — is adapted from the English children’s song This Old Man. Sung for more than half a century, it was the first advertising jingle in Taiwan to obtain a registered “sound trademark,” and the industry jokingly calls it “the national anthem of advertising.” This tells us something: Green Oil Essence’s brand equity long ago outgrew the product itself and became a shared cultural symbol across generations.

One common myth needs correcting. The claim that “Hsin Wan Jen was founded in 1933” circulates online, but according to company and public records the pharmaceutical business began in the late 1940s after the war, and Green Oil Essence reached the market in 1964 — not before the war in 1933.

2. Formula and Pharmacology: A Synergy of Four Cooling–Analgesic Ingredient Classes

Green Oil Essence is classified in Taiwan’s drug system as a Category B over-the-counter medicine, with the health authority license number 內衛成製字第 001347 號, manufactured by Hsin Wan Jen Chemical & Pharmaceutical (Fengyuan District, Taichung). According to the manufacturer’s published composition, the active ingredients per 1 g are approximately:

Trace botanical and aromatic components (such as peppermint oil, lavender oil, and chlorophyll-copper coloring, which gives the liquid its signature green) round out the classic formula.

1. Menthol

The core of the “cooling” sensation. Menthol acts on the TRPM8 cold receptors in skin and mucosa, creating the brain’s illusion of “turning cold.” At the same time, through a counter-irritant mechanism, it produces a mild analgesic and anti-itch effect on minor pain and itching, and briefly dilates local blood vessels. This is the source of that nose-piercing coolness after application. At 310 mg/g, menthol is the dominant active in Green Oil Essence.

2. Methyl Salicylate (Wintergreen Oil)

The analgesic and anti-inflammatory workhorse. After percutaneous absorption, methyl salicylate has a local action similar to a non-steroidal anti-inflammatory drug, effective for muscle soreness and aching limbs. But it is also a potential source of acute salicylate poisoning. Taiwanese regulators explicitly cap methyl salicylate at no more than 1.8 g per day; overdose can cause tinnitus, nausea, rapid breathing, and other salicylate-toxicity symptoms.

3. Camphor

Camphor provides mild local anesthesia and an alternating warm–cool counter-irritant effect, soothing itch from insect bites and minor muscle aches. Camphor is also one of the most safety-sensitive ingredients in Green Oil Essence (see contraindications below).

4. Eucalyptus Oil and Clove Oil

Eucalyptus oil (main component 1,8-cineole) contributes anti-itch, mild local anesthetic, and antibacterial action, and lends Green Oil Essence its distinctive herbal aroma. Clove oil (main component eugenol) has local anesthetic and antibacterial properties and is folklorically used for temporary relief of minor toothache.

Overall, Green Oil Essence is designed as a composite topical oil following the logic of “cooling counter-irritation + mild analgesia + herbal antibacterial aroma.” It is positioned for fast relief of everyday minor symptoms — not as a curative drug.

3. Official Indications: What It Is Actually For

According to the registered license, the indications for Hsin Wan Jen Green Oil Essence are fairly broad, including:

These are the classic scenarios in which older generations of Taiwanese reach for Green Oil Essence: a dab on the temples and philtrum when feeling stuffy and faint, under the nose before a car ride, a touch on a mosquito bite to stop the itch, a rub on sore muscles. Folk usage has extended further — a few drops on underwear to reduce sweat odor, or applied to acupoints to “clear the head and refresh the mind.” These extended uses are largely experiential, lack rigorous clinical evidence, and should be understood as “comfort relief” rather than guaranteed efficacy.

4. Correct Use

  1. Topical application: Apply an appropriate amount to the affected area or to the temples, philtrum, or brow point, and massage gently until absorbed.
  2. Headache, congestion, refreshing: Apply a small amount to the temples and both sides of the nostrils; avoid getting it directly inside the nostrils or in the eyes.
  3. Insect bites and itch: Dab onto the bite, several times a day.
  4. Muscle soreness: Apply to the sore area and rub gently, achieving relief through counter-irritation and methyl salicylate.
  5. Motion sickness: Apply a small amount under the nose or to the temples before departure, reapplying en route if needed.

Always wash hands after use, and avoid rubbing the eyes or contacting mucous membranes and wounds.

5. Safety Contraindications and Warnings (Read Carefully)

Although Green Oil Essence is an open-shelf over-the-counter product, “easy to obtain” does not mean “safe for everyone.” Key safety reminders:

1. Never Take Internally

Green Oil Essence must not be swallowed. Accidental ingestion can cause vomiting, tinnitus, and even camphor and salicylate poisoning. A folk “remedy” of “drinking Green Oil Essence in water” has circulated — this is dangerous and wrong and must be avoided. Keep the green bottle out of children’s reach.

2. Forbidden for Infants and Children Under 2

Green Oil Essence contains menthol and camphor and is prohibited for infants and children under 2 years old. Infants have thin skin, a large surface-area-to-body-weight ratio, and a high percutaneous absorption risk. Camphor can trigger convulsions and central-nervous-system toxicity in young children; menthol can provoke laryngospasm and respiratory depression in infants. This contraindication is consistent with White Flower Oil and Tiger Balm. See Can Babies Use Medicated Oils? Under-2 Contraindications.

3. Forbidden for G6PD Deficiency (Favism)

This is a point Taiwanese pharmacists repeatedly stress. Because Green Oil Essence contains camphor and methyl salicylate, it is on the list of topical products that people with G6PD deficiency (favism) should avoid. Taiwanese pharmacists have repeatedly come forward to debunk the online rumor that “people with favism can freely use Green Oil Essence, Mentholatum, or Tiger Balm” — these camphor/salicylate-containing products are all on the avoidance list for G6PD-deficient individuals and may trigger acute hemolysis. For the full list and alternatives, see G6PD Deficiency and Medicated Oils: Complete Contraindication List.

4. Do Not Use on Cuts, Wounds, or Broken Skin

Green Oil Essence should not be applied to cuts, open wounds, or broken skin. It causes intense stinging discomfort and increases the risk of rapid absorption through the wound. Use only on intact skin surfaces.

5. Methyl Salicylate Dose Ceiling

Methyl salicylate intake must not exceed 1.8 g per day. Everyday small dabs are far below this, but heavy, frequent, large-area, or prolonged use — especially in children, or combined with other salicylate patches and ointments — carries a salicylate-poisoning risk. People taking anticoagulants (such as warfarin) should be especially careful; see Medicated Oils and Anticoagulant Medication Safety Guide.

6. Pregnancy and Sensitive Skin

Pregnant women should consult a doctor or pharmacist before using topical oils containing camphor and methyl salicylate. First-time users should patch-test a small area on the inner forearm and watch for rash, burning, or other allergic reactions. See Medicated Oils in Pregnancy: What to Avoid by Trimester and Medicated Oil Allergy and Skin Sensitivity Guide.

6. Green Oil Essence vs. White Flower Oil vs. Tiger Balm: How to Choose

These three are common in Taiwanese household medicine boxes, with slightly different positioning:

In short: choose Green Oil Essence for cool penetration and refreshment, choose Tiger Balm for a long-lasting balm massage, and note that the core contraindications of all three (infants, G6PD deficiency, never internal) are essentially the same. For a deeper comparison, see Asian Medicated Oils vs. Western Topical Analgesics.

7. Spotting Counterfeits and Storage

Green Oil Essence is widely sold in Taiwanese pharmacies and convenience stores, commonly in 3 g (small), 5 g (medium), and 10 g (large) sizes. When buying, look for the license number 內衛成製字第 001347 號 and the Hsin Wan Jen Chemical & Pharmaceutical mark on the packaging, and avoid unlabeled bulk or grey-market knockoffs. After opening, screw the cap tight and store in a cool, dark place; volatile components (menthol, eucalyptus oil) dissipate over time, so discontinue use if the aroma noticeably fades or the product smells off. For storage details, see Medicated Oil Storage and Expiry.

Conclusion

Green Oil Essence is Taiwan’s “national medicated oil” not only because of that jingle everyone can hum, but because it turned the classic cooling counter-irritant formula of menthol, camphor, eucalyptus oil, and methyl salicylate into a cheap, handy, everywhere-available everyday remedy. But “easy to get” has never meant “no contraindications.” Forbidden under 2, forbidden in G6PD deficiency, never internal, never on wounds — these four red lines are worth every Taiwanese household remembering even more firmly than the jingle.

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This article is health-education and cultural information, not medical advice. Before using any medicated oil, individuals with special conditions, pregnant women, infants, and patients with chronic illness should consult a doctor or pharmacist.