SINGAPORE - With the weeks-long sweltering heat persisting for the rest of the month and drier weather expected to stay till September, doctors have cautioned the public against heat-related health risks.

During the hotter months, Khoo Teck Puat Hospital sees up to three times more patients with heat-related injuries than in the cooler months, said Dr Kanak Naidu, senior consultant at the hospital's Department of Acute & Emergency Care.

The injuries range from mild conditions such as heat rash, heat cramps - which refer to painful muscle spasms due to dehydration and overworked muscles - and heat exhaustion, to more severe forms like heatstroke.

Dr Derek Li, a family physician at Raffles Medical, said he has seen more patients with flare-ups of skin ailments such as eczema and hives, which can be triggered by heat and dehydration from sweating.

He added that people who work outdoors are more prone to headaches, malaise, body aches, dizzy spells and poor concentration.

"But these symptoms are difficult to attribute purely to heat stress alone... (with) the background incidence of Covid-19 and dengue fever in the community, all of which can also cause similar symptoms."

Dr Li expects the number of heat-related complications to rise in the next few weeks, with more large-scale sporting events resuming.

The National University Polyclinics and the National Healthcare Group Polyclinics (NHGP) have been seeing a rise in patients with mild conditions such as heat rashes and eczema flare-ups. 

Family physician Yeap Youwen from Hougang Polyclinic, which is under NHGP, said he has been seeing patients with heat rash and heat cramps daily.

Dr Lee Joon Loong, medical director of Paddington Medical Clinic in Bedok, said the warm and dry weather becomes a double whammy for patients with gastroenteritis, who are already predisposed to dehydration owing to their symptoms of vomiting and diarrhoea.

April and May this year has seen some of the highest temperatures recorded in Singapore.

April 1 saw the second-highest temperature on record here, at 36.8 deg C in Admiralty. This was just 0.2 deg C shy of the all-time high recorded in Tengah on April 17, 1983.

May 13 was the hottest May on record, at 36.7 deg C, also recorded in Admiralty.

The National Environment Agency's Meteorological Service Singapore forecast that the rest of this month would see daily maximum temperatures hovering between 34 deg C and 35 deg C on most days, with the mercury hitting 36 deg C on a few days.

A climate report card released last week by the World Meteorological Organisation stated that 2021 was between the fifth and seventh hottest years on record, despite it being a La Nina year, a climate phenomenon which causes a temporary cooling in the Pacific.

Dr Rachel Lim, SingHealth Polyclinics' clinical lead for its preventive care workgroup, said: "With higher environmental temperatures, the body would find it harder to lose heat to its surrounding atmosphere. This causes the core body temperature to increase, increasing risk of heat-related complications."

Young children, who tend to perspire less, and the elderly, whose ability to remove heat from their body has dropped, are more at risk of heat-related complications, added Dr Lim.

Other groups at risk include those with obesity, patients with chronic conditions such as cardiovascular disease, heavy alcohol drinkers and foreigners not used to the local weather.

"Perspiration is a common method of heat removal for the body. However, this method becomes less effective in a humid environment like Singapore's," noted Dr Lim.

Dr Ang Shiang Hu, chief of Changi General Hospital's accident and emergency department, said exertional heat injuries - caused by a rise in body temperature due to intense physical activity - are more common here, compared with classic heat injuries reported during heatwaves in temperate regions.

Outdoor workers, which include cleaners and construction workers, should be given more rest breaks, cooling options and shelter, said Associate Professor Jason Lee from the NUS Yong Loo Lin School of Medicine.

He added: "The transition phase now, where it changes from normal to very hot temperatures, is usually the most dangerous phase because some are too slow in changing their behaviours to slow down to protect their health."

While classic heat illnesses - caused by exposure to environmental heat and poor heat-releasing abilities - are less common here, the elderly, especially those with chronic diseases and who live in less ventilated conditions, are more susceptible to them, doctors said.

Seniors with cardiovascular disease, for example, can collapse from heat stress due to oxygen deprivation to internal organs.

When exposed to scorching heat, the body works to cool off by shifting blood flow from the organs to the skin, but those with heart disease may not be able to cope with the increased demands.

Therefore, it is important to keep a close watch on the bed-bound, or those unable to communicate, as they may not be able to move to a cooler place, or voice out their discomfort, said Associate Professor Kenneth Tan, head of Singapore General Hospital's Department of Emergency Medicine.

These days, Paddington Clinic's Dr Lee's parting words to his patients are: "Drink lots of water."

Beating the heat

To avoid heat stress:

• Go for loose-fitting, thin and absorbent clothing and a hat. 
• Schedule outdoor activities during cooler hours of the day, before 9am and after 6pm. Avoid intense outdoor activities between 10am and 4pm. 
• Drink at least two litres of water a day. Stay hydrated before and during outdoor work or exercise. People with medical conditions should check their fluid requirements with their doctors. 
• For those who are not used to the heat, they have to gradually increase their heat tolerance by slowly raising the intensity or duration of work performed under the sun. Not getting acclimatised to the heat will increase their risk of getting heat injuries.
• If you are feeling unwell due to the heat, stop your activity and move to a shaded or air-conditioned place. Drink water and seek medical help early.
• Avoid strenuous exercise if you are unwell.
• Outdoor workers should take periodic breaks in a shaded area. Handheld portable fans can be used to cool the body down as you perspire.
• Avoid hot food and drinks as much as possible.
• Iced slushies, but only of the non-sugary kind, can help. Drinks high in sugar and alcohol content should be avoided.
• Do more aerobic fitness exercises to train the heart to pump blood more efficiently and raise one’s thermal tolerance.
• Moisturise skin to manage heat rashes and eczema. Topical steroids of appropriate potency and oral antihistamines may help with eczema flare-ups. 

Common treatments for heat injury cases:

• Oral hydration with isotonic fluids.
• Sponge or spray the patient with cold water and fan him.
• Remove excess clothing. Place a cold, wet cloth to areas such as the neck, armpit and groin areas to decrease body temperature.
• In the hospital, cold intravenous fluids and cooling blankets may be used.

Sources: Dr Keith Ho, head of Alexandra Hospital’s Urgent Care Centre, Alexandra Hospital, and senior consultant at National University Hospital’s Emergency Medicine Department; Dr Kanak Naidu; Associate Professor Kenneth Tan; Associate Professor Jason Lee; Dr Rachel Lim, Dr Yeap Youwen, Dr Loh Jun Hao, family physician at Jurong Polyclinic, National University Polyclinics

This article was first published in The Straits Times. Permission required for reproduction.