Is taking a hot shower after drinking or eating bad for you and can it really cause white spots on the skin?

Despite the scorching heat and perpetual sweaty dampness on our skin, many Singaporeans would rather step into a hot shower than a cold one. And why not? As the water hits your body and the steam rises from your skin, tense muscles relax and you can imagine the stress from a long workday melting away.

In a way, the heat from hot showers functions like an “off” switch for your body’s “fight or flight” response system, said family physician Dr Andrew Fang from Doctor Anywhere, to “induce a more relaxed body and mental state”.

Moreover, heat can cause your blood vessels in the skin to dilate and allow an increased blood flow to the body’s surface. “This can raise metabolic rate and provide a temporary boost to energy levels.”

The increased blood circulation has another benefit, according to Cindy Chan, a physiotherapist from Asian Healthcare Specialists: Soothing sore muscles and post-workout pain. “Heat can increase blood circulation, which aids in the recovery process by delivering nutrients and oxygen to the muscles.”

Respiration-wise, the steam from a hot shower can also “help moisturise and soothe the respiratory passages, providing relief for congestion and mild respiratory issues”, said Dr Terence Lim, the medical director of Assure Urology & Robotic Centre.

Besides, a hot shower is far more welcoming to get into than a tub of ice-cold water – a purported health-promoting technique that has been gaining popularity lately – and a story we’ll save for another day.

FACTS OR MYTHS ABOUT SHOWERING

“While hot showers per se do not usually directly cause health issues, they may aggravate certain skin conditions,” said Dr Derek Lim, an associate consultant from National Skin Centre.

“The most common are patients with eczema who enjoy taking long hot showers. Such showers remove oil and moisture from the skin, leading to dry, itchy and flaky skin, and worsening their eczema.”

Added Dr Derek Lim: "Hot water strips the skin of its natural oils, which are usually involved in maintaining our skin barrier. This leads to dryness, scaling, redness and itch". 

That's not to say you should avoid hot showers altogether. "In general, most people without any skin problems may take hot showers without any issues. However, as you age, your skin gets drier and may be aggravated by the use of hot water," he said. In fact, most doctors recommend taking hot showers that are no longer than 15 minutes to avoid drying out your skin. 

But what about other notions you may have heard that supposedly arise from taking hot showers, such as causing white skin spots after a sweaty session in the gym or post-run, preventing joint aches or interrupting digestion after a meal? We find out from the experts:

1. Taking a hot shower after exercising or sweating can result in white spots on the skin: False

White spots can be due to many reasons, such as vitiligo, fungal infections and post-inflammatory changes, said Dr Derek Lim. But they are not caused by hot showers after exercising or sweating, he said.

The most common condition that can be attributed to white spots after showering is likely tinea versicolor, which is a superficial fungal infection of the skin caused by Malassaezia furfur. “Heat, sweat and moisture promote the growth of this fungus in individuals who exercise regularly,” he said.

To prevent these spots, shower with lukewarm water after exercising, he said, and dry yourself to prevent fungal growth. To treat the white spots, a combination of antifungal washes and creams, and in more severe cases, oral antifungal tablets, are prescribed, he said.

2. Shower with hot water to kill the bacteria or fungus causing your skin infections: False

Sometimes, the preference for hot showers could be borne from habit and misconception, said Dr Derek Lim. “Patients may acquire the habit of showering with hot water when young and believe that hot water can better remove dirt and germs.”

That, of course, is a misconception. “The temperature of hot showers is generally not enough to kill bacteria and fungus on the skin,” he said. These patients would need antiseptic or antifungal washes, combined with antibiotics or other creams, to treat the infections, he said.

3. Don’t shower with hot water immediately after eating – it disrupts digestion: True

A process known as hyperthermic action is stimulated in your body when you take a hot shower, which raises your internal body temperature by a degree or two, according to Dr Fang. The increased warmth you feel after a satisfying meal? That’s your body directing more blood flow to your digestive organs to break down the meal.

But if you head straight into a hot shower, the blood that was intended for digestion will flow to other parts of the body instead and delay digestion, he said. “Having a hot shower immediately can also increase one's heart rate, which feels uncomfortable on a full stomach.”

4. Don’t shower after drinking – the alcohol will take longer to break down in your body: False

The organ that is primarily involved in the processing of alcohol is the liver, said Dr Fang. “If you consumed alcohol and took a shower soon after, alcohol will continue to be processed by the liver at its regular rate.”

However, he said, hot showers can cause the dilation of blood vessels, which causes alcohol to be absorbed faster into your bloodstream, which can result in a quicker onset of the effects of alcohol.

“Alcohol consumption is dehydrating – and the combination of alcohol and a hot shower – could leave an individual even more dehydrated, due to the sweat produced during a hot shower,” said Dr Fang.

5. Women should take hot showers to ease the pain of menstrual cramps: Somewhat true

Your uterus is essentially one big muscle and it contracts to shed its lining every month to create your period, said Dr Sherry Ross, a women’s health expert and author of She-ology: The Definitive Guide To Women’s Intimate Health. Period.

So, like how hot showers can relax tense muscles, the heat too, can ease the uterine muscle tissue to lessen the cramps, said Assistant Professor Jessica Shepherd, the director of Minimally Invasive Gynecology at The University of Illinois College of Medicine at Chicago, US. Try taking a hot shower and face the spray while you’re at it.

There’s no harm in trying a hot shower, said Dr Fang, though the effect is subjective to the individual. “Some women find applying a heat patch or a warm shower can help ease menstrual cramps. But it may not apply for all and only provides temporary relief.”   

6. Men should avoid long, hot showers if they're trying for a baby: True

High temperature is simply bad news for sperm formation or spermatogenesis, said Dr Jay Lim, a urologist from PanAsia Surgery, which is why nature intended for the testicles to exist outside of the body.

“The optimal temperature for sperm formation is 2 to 4 degrees Celsius lower than the body temperature. And research shows that every 1-degree increase in testicular temperature decreases spermatogenesis by 14 per cent,” he said.

This is why it doesn’t bode well for men to take long, hot showers. “High temperatures have been associated with decreases in semen parameters”, said Dr Fang. Luckily, the effects seem to be reversible. “Most studies reported an improvement of sperm and semen quality within three months of heat cessation,” he said. If you are starting a family, it’s best to take warm showers instead.