Can prickly heat powder and cooling water really beat the heat? The facts behind some popular remedies
What’s the difference between heat and heatiness? And can those barley drinks you order at the food court cool you down? Experts explain how they work, their limitations, and when they can do more harm than good.
(Photo: iStock/coffeekai)
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Living in the tropics, we often view the occasional thundery shower with both dread and relief simply because when it rains, it really rains. But the downpour also provides a much-appreciated respite from the heat – until the temperature climbs back up into the mid-30-something again. You know better than to ditch the AC remote control and handheld fan; as you know it, heat with a capital “H” is always around the corner.
HEAT VS HEATINESS
In conventional medicine speak, “heat” refers to an elevated body temperature or a sensation of being hot due to the environment or exertion. The general term for this is hyperthermia.
An example of hyperthermia is heat exhaustion, which is the result of losing excessive water and salt through heavy sweating. Heatstroke, the most severe form of hyperthermia, is a life-threatening situation where your body’s core temperature rises above 40°C.
“Products like the prickly heat powder, calamine lotion, and cooling body wipes can certainly improve comfort in hot weather. They may help with sweating, skin irritation, and create a cooling sensation,” said Dr Sharen Tian, a family physician with Raffles Medical.
However, she noted, none of those products can lower your body’s core temperature. “They should not be relied upon to prevent heat exhaustion or heat stroke,” said Dr Tian. For heat exhaustion, she advised, you’re better off sticking to the fundamentals, such as staying well hydrated, seeking shade, using air-conditioning, and avoiding strenuous activities during the hottest parts of the day.
Heatiness, on the other hand, is a traditional Chinese medicine (TCM) concept to explain the state of imbalance caused by excessive hot yang energy or a deficiency in cooling yin energy.
Other than the weather, eating too much heaty foods such durian, red meat, deep-fried food and chocolate, is also deemed to upset the balance – and lead to fever, sore throat, mouth ulcers, acne and excessive thirst, according to Yan Yew Wai, an acupuncturist at Tan Tock Seng Hospital’s Complementary Integrative Medicine Clinic, on HealthHub.
HOW DO COOLING PRODUCTS WORK?
If you grew up in 1970s or 1980s Singapore, you might remember emerging from the shower, coloured a lighter shade of yourself by the prickly heat powder or calamine lotion that Mum liberally applied on you to keep you cool and rash-free.
Growing up, you probably also drank enough homemade TCM concoctions worth your weight – not limited to barley drink, chrysanthemum tea, green bean soup, liang teh and ling yang drink. And even more if you had a cough or sore throat – the classic symptoms of heatiness in TCM-speak.
Now that you’re all grown up, you might wonder: just how do these products and brews work to help you beat the heat? Are they really effective? Here’s a look:
1. Prickly heat powder
Ex-National Servicemen would be familiar with this product, especially the iconic Snake Brand. What it contains to keep sweat and heat rash at bay is likely a combination of talc or cornstarch, zinc oxide, fragrance and menthol, said Dr Tian.
“Talc and cornstarch absorb excess moisture and sweat from the skin surface,” she explained, while “zinc oxide acts as a skin protectant and helps reduces irritation.” “Menthol activates cold receptors in the skin, creating a cooling sensation.”
As welcoming as the cool feeling is, don’t apply with abandonment as excessive powder – when there’s a visible powder buildup on your skin – can clog sweat ducts, trap dirt and worsen heat rash, said Dr Tian.
Skin dryness and irritation may also occur, or you may develop skin irritation or allergic reactions. “The inhalation of the powder, especially by infants and young children, may irritate their respiratory tracts,” she said.
It is also prudent not to use the powder on broken skin, eczema flares, infected rashes, or open wounds, said Dr Tian. If you have sensitive skin, don’t combine the powder with multiple fragranced products.
2. Calamine lotion
If you’ve had chicken pox before, you might remember having this over-the-counter medication dabbed onto the itchy spots. It usually contains zinc carbonate, ferric oxide, and glycerine or other soothing agents, said Dr Tian.
“Calamine lotion is excellent for the symptomatic relief of heat rash, insect bites, mild sunburn and itchy skin,” she said. “The zinc carbonate and ferric oxide soothe irritation and form a mild protective barrier on the skin. You can experience a cooling effect from the lotion evaporating from your skin.”
But don’t overdo it. “Applying a thin layer two to four times daily is generally sufficient,” said Dr Tian. “Overdoing may dry the skin out and ironically, worsen the itch.” Also, avoid applying calamine lotion on deep wounds or infected skin. Don’t apply calamine lotion immediately before other medicated creams, unless advised by a healthcare professional, she added.
3. Cooling body wipe
Like prickly heat powder and cooling sanitary pads, these wipes are typically infused with menthol to create the cooling effect. “The common ingredients can also include peppermint, alcohol, aloe vera, water and fragrance,” said Dr Tian.
“The alcohol evaporates rapidly, producing a cooling effect, while menthol stimulates cold receptors in the skin,” she said. “Aloe vera may help soothe and moisturise the skin.”
The wipes aren’t a bad choice if you want temporary heat relief but note that the cooling sensation is “largely sensory”, noted Dr Tian – which means they don’t bring down your core temperature in any way.
4. Cooling water
They may look like mineral water but OGs would recognise the labels on the bottles – now largely plastic instead of glass. The more popular brands include Three Legs Cooling Water, Laoshan Oldenlandia Water, and Four Tens Antelope & Rhino Brand Cooling Water.
The taste of these TCM concoctions ranges from neutral to slightly medicinal; some may leave a mild alkaline or slightly bitter aftertaste. That flavour profile is likely thanks to the addition of shi gao (gypsum fibrosum) or snake-needle grass (oldenlandia diffusa).
In TCM, cooling waters are favoured for bringing down high fevers that are accompanied by extreme thirst and excessive perspiration, said associate senior TCM physician, Kok Zirui, from Kwong Wai Shiu Hospital. If your gums are inflamed, which in TCM, is linked to an over-indulgence in fried or spicy food, cooling waters may help to calm them down, said Kok.
Angely Shuo Sun, a TCM physician from Raffles Healthy Longevity, said that shi gao, “a very cooling substance” is also “commonly used when people experience symptoms such as sore throat, mouth ulcers, excessive thirst, or a sensation of internal heat”.
But remember, these are not plain water; drinking too much cooling water (best to check the label for instructions) can lead to “digestive discomfort, bloating, loose stools, reduced appetite, or increased sensitivity to cold”, warned Sun. “Taking it together with large amounts of cold, or iced foods and drinks may further weaken digestive function.”
5. Liang teh
Liang teh, which literally means “cooling tea” in Hokkien, is usually a brew of various TCM herbs. But “there is no single formulation that defines liang teh”, said Sun. “The exact ingredients vary by brand or recipe. Different liang teh formulations may have different functions, depending on their ingredients.”
Commonly, the sweet, dark-brown tea consists of honeysuckle (jin yin hua), chrysanthemum, spica prunellae (xia ku cao) and monkfruit (luo han guo).
“In TCM, jin yin hua helps clear heat and relieve heat-related toxicity,” Sun explained. “Chrysanthemum helps clear heat and soothe the eyes. Xia ku cao helps clear liver heat. Luo han guo soothes the throat and relieves dryness.” Taken together, these herbs target heaty symptoms such as sore throat, mouth ulcers, dry throat, bad breath, or excessive thirst, she said.
6. Ling yang drink
For the uninitiated, the drink is made by boiling shavings of antelope horn – more specifically, the horns of the saiga antelopes that live in Kazakhstan, Russia and Mongolia.
The resulting shavings, known as ling yang (cornu saigae tataricae), “is considered strongly cooling and is traditionally used to clear intense heat, such as high fever, particularly excessive heat affecting the liver system”, said Sun.
“Due to its strongly cooling nature, it is generally not intended for long-term, routine consumption, particularly for individuals with cold constitutions.”
Kok agreed. “Greater public education is needed to clarify that ling yang is a powerful medicine, not a casual, every-day cooling drink, and that its use should be reserved for appropriate clinical situations,” he said.
Another reason to temper ling yang’s use is that the saiga antelope “has historically been classified as critically endangered”, said Kok. “Thanks to conservation efforts, it was reclassified to ‘near threatened’ status in 2023. It’s a significant recovery – though the species remains vulnerable.”
Kok highlighted that “research and development of man-made ling yang extract is currently ongoing”. If you want to do your part for conservation, your best bet is to consult a qualified TCM physician, who can advise on appropriate and sustainable alternatives, he said.
7. Home brews such as chrysanthemum tea and barley drink
In TCM, brewed chrysanthemum tea (not the same as those ready-to-drink brands) is great for dispelling “wind heat, which can be broadly interpreted as reducing inflammation in the respiratory system caused by viruses”, said Kok. He recommended making the floral brew for the “initial stages of flu to reduce mild fever, headache and cough” as well as help “relieve sore eyes that may occur during a flu”.
Sun also recommended chrysanthemum tea for “symptoms of heatiness after prolonged screen use, lack of sleep, or exposure to hot weather”.
However, don’t chug it like water. “Those who are sensitive to cold foods or frequently experience loose stools should avoid drinking large amounts regularly,” said Sun. As a general rule of thumb, added Kok, these drinks “should be consumed in moderation and must not substitute for daily water intake”.
As for the popular barley drink, Kok said that it is deemed to “dispel dampness from the body by promoting urination”. It can also alleviate lethargy caused by the hot and humid weather by improving digestion and eliminating excess water from the body, he added.
However, the barley drinks that you order at the food court or hawker centre probably won’t cut it. “The common barley used in typical barley drinks does not carry the medicinal ‘cooling’ properties often attributed to it,” said Kok. “It is Chinese barley (coix seed) that possesses the desired cooling effect – a distinction that is frequently misunderstood.”
Furthermore, “the typical barley drinks sold commercially may contain added sugar, which can paradoxically make the body more ‘heaty’ rather than cooling it”.
Don’t over-consume it though. “Individuals, who are already dehydrated, should be cautious as this herb promotes further water loss,” warned Kok. Generally, “TCM and western medicine should be taken at least two hours apart”, he highlighted. “However, most barley and chrysanthemum drinks are closer in concentration to food than medicine, and do not require such strict separation.”
Source: CNA/bk
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