Delhi's summer has arrived harder and earlier than expected this year. With temperatures repeatedly crossing 40°C, the effect on hospitals is already visible. Outpatient departments across the city are reporting a steady rise in children arriving with heat-related illness, and peak summer is still ahead. What makes this surge concerning is not only its size but its timing, because the season has barely begun. Much of it, however, begins at home, where the early warning signs are easily missed. Dr. Ravi Malik, Founder & Medical Director, Malik Radix Healthcare (MRHC) lists the following signs and symptoms that should not be missed by parents.Heat-related illness Begins QuietlyMost children do not suddenly collapse from heatstroke. Heat-related illness tends to begin quietly. The early changes are subtle ones in behaviour and energy, and they are easily attributed to summer fatigue, a disturbed night of sleep, or a mild viral infection. Quite often, these are the first signs of heat exhaustion. Paediatric guidance from the Indian Academy of Pediatrics and the American Academy of Pediatrics is consistent on one point. Children are more vulnerable to heat than adults. Their bodies heat up faster, they lose fluids more quickly, and they register thirst later than adults do. The signs parents most often missOne of the most commonly missed signals is reduced activity. A child who is normally energetic begins to want to lie down and loses interest in play. During heatwaves, a phrase heard repeatedly in the OPD is that the child "just isn't playing like usual." That change in energy deserves attention. It can point to dehydration, overheating, or an electrolyte imbalance well before any more visible symptom appears. Irritability is another warning sign that tends to be overlooked. A heat-affected child may turn cranky, emotionally unsettled, or excessively sleepy through the day. Some stop eating properly. Others complain of headaches after returning from school. In infants, dehydration may show up only as excessive crying, refusal to feed, dry lips, or a reduction in wet diapers.Vomiting and fever are often misreadVomiting in summer is frequently misread. A large number of children brought to hospital with vomiting are not suffering from food poisoning at all. They are overheated. Heat-related vomiting commonly follows prolonged outdoor exposure, a long school assembly, sports activity, travel in a poorly ventilated vehicle, or prolonged sweating. The context in which the vomiting occurred matters a great deal. Fever can mislead in a similar way. Heat exhaustion itself may raise body temperature and produce flushed skin, nausea, headache, and lethargy. A persistent high fever is a different matter. So are changes in behaviour, seizures, breathing difficulty, or poor responsiveness. These should not be waited out.Heat exposure indoorsThere is growing clinical concern about indoor heat exposure. Many parents associate heat illness with direct sunlight alone. A child can become significantly dehydrated indoors as well, whether in an overcrowded room, on a school bus, or during a power cut at night. Poor sleep in an overheated room leaves a child fatigued, irritable, and unwilling to eat the following day.Why drinking water alone isn't enoughMany parents assume that a child who is drinking water is adequately hydrated. This is a misconception. Children playing outdoors lose both water and sodium through sweat, and a child who drinks only plain water replaces the fluid while the lost electrolytes go unreplaced. Parents are advised not to wait for a child to ask for water during a heatwave. Hydration should be proactive, particularly for school-going children involved in sports or outdoor activity. Warning signs to watch for include dark yellow urine, reduced urination, dry lips, dizziness, headache, or unusual tiredness with muscle cramps. When to seek urgent medical attentionThe most serious complication is heatstroke. It is a medical emergency, and it can affect the brain, kidneys, and other organs within a short span of time. Parents should seek urgent medical attention if a child shows any of the following - persistent vomiting or an inability to drink fluids, confusion, fainting, or extreme drowsiness, breathing difficulty, seizures, or very low urine output.PreventionPrevention, in most cases, comes down to straightforward measures. Encourage fluids before a child feels thirsty, and offer ORS, lemon water, coconut water, or buttermilk during outdoor activity. It is best to avoid outdoor play between 11 am and 4 pm. Ensure proper ventilation during sleep, either by keeping doors and windows open or through AC and fans. For infants, maintain frequent breastfeeding and avoid overdressing. Never leave a child inside a parked vehicle, even for a short while.The takeawayThe children who arrive in a critical state are rarely the ones whose illness looked dramatic from the start. They are far more often the ones whose early signs were quiet and were read as something else. A child who is a little subdued, who skips a meal, who sleeps oddly through the afternoon, is a child worth a second look. Heatwaves are growing longer and more intense each year. Recognising these signs early can prevent a hospital visit. In the most serious cases, it can save a child's life.