Are all mosquito repellents equally safe? Internal medicine expert Dr Chirag Tandon explains
Mosquito Season in India: Why the Repellent on Your Shelf Deserves a Second Look
Bharatmorningnews.com – Every year, as temperatures climb and monsoon rains pool in urban drains, Indian households reach for coils, vapouriser plugs, and aerosol cans with the same urgency they once reserved for winter blankets. Dengue, chikungunya, malaria, and Japanese encephalitis continue to claim thousands of cases across the subcontinent, making insect repellent a near-essential item in most Indian kitchens and bedrooms. Yet the question most families never pause to ask is whether every product on the shelf carries the same safety profile — and whether the way it is being used at home is actually the safest way.
Dr Chirag Tandon, director of Internal Medicine at Shardacare – Healthcity in Greater Noida, with more than eighteen years of experience managing acute and chronic adult conditions across multiple organ systems, says the answer is a firm no. While all repellent formulations share the basic goal of killing or deterring mosquitoes, their chemical delivery mechanisms differ enough to create distinct risk landscapes for the people sharing the same room.
Coils: The Smoke Problem
The most ubiquitous form of indoor repellent in Indian households — the small, coiled disc that smoulders on a plate or clip — works by slowly burning a treated substrate and releasing active ingredients into the air. Dr Tandon cautions that the combustion process also generates particulate smoke, which can irritate the eyes, nasal passages, and throat, especially in poorly ventilated rooms or after extended overnight use.
"This also poses a more significant risk to asthmatics, individuals suffering from allergies or other ailments connected with the lungs."
For families with a member who has reactive airways, the doctor's guidance is straightforward: keep a window cracked or a fan running to maintain airflow, position the coil well away from the sleeping head, and never leave it within arm's reach of a toddler. The smoke is not merely an annoyance; in a sealed bedroom it becomes a low-grade irritant load that compounds existing respiratory vulnerability.
Vapouriser Plugs: Gradual Release, Specific Rules
Electric vapouriser units heat a liquid or solid pad at a steady rate, metering out repellent molecules over many hours without open flame. Dr Tandon considers them well suited to enclosed indoor spaces, provided two conditions are met. First, the user must follow the manufacturer's instructions regarding placement height, room size, and maximum continuous runtime. Second, the room should retain some degree of ventilation so that concentrations do not climb unchecked.
A particular caution applies to households with young children or pets. The doctor advises keeping these vapouriser units out of reach and out of the immediate breathing zone of small kids and animals, since their lower respiratory capacity makes them more sensitive to airborne chemical loads than adults.
Sprays: Short-Term Utility, Longer-Term Caution
Aerosol and pump sprays fall into two broad categories: area-treatment sprays that coat surfaces and kill resting mosquitoes, and personal sprays applied directly to skin or clothing. Dr Tandon notes that area sprays are effective for a limited window — useful before settling into a garden pavilion or a balcony, for instance — but they are not a substitute for personal protection when a person is outdoors for an extended period. In that scenario, a skin-applied repellent is the more appropriate tool.
"Sprays can be hazardous if their directions are ignored. For a treatment spray, one may have to avoid an area for up to three hours, but be wary not to apply such a product to broken or damaged skin."
The three-hour re-entry interval exists because the active ingredient needs time to dry and bind to surfaces; lingering in a freshly sprayed enclosure while the chemical is still volatile increases inhalation and dermal exposure. Applying any repellent to cuts, abrasions, or eczematous patches bypasses the skin's natural barrier and can provoke local irritation or systemic absorption.
The Over-Application Trap
Perhaps the most common household error, according to Dr Tandon, is the belief that doubling or tripling the recommended dose yields proportionally greater protection. It does not. Once the labelled quantity has been applied, additional product simply raises the chemical load on skin, mucous membranes, and the surrounding air without extending the duration or breadth of mosquito deterrence. The marginal gain is zero; the marginal risk is real.
He also warns against combining different repellent brands or types in the same space unless the product directions explicitly permit the combination. Layering an unknown cocktail of pyrethroids, DEET, picaridin, or essential-oil blends can push total exposure past the threshold at which mild symptoms — headache, dizziness, transient dyspnoea — begin to appear.
"Avoid mixing products unless there is no other alternative or the directions state there is no alternative. If one experiences prolonged inability to breathe easily due to any product, it is advisable to find a better-ventilated environment, and if it persists, seek appropriate medical attention."
Practical Takeaways for Indian Households
Given the density of urban housing, the prevalence of shared ventilation shafts in apartment blocks, and the seasonal spike in vector-borne disease notifications from state health departments, a few grounded habits can meaningfully lower household risk:
Read the label before the first use of any new product, and re-read it each season. Match the product type to the setting — a vapouriser for a bedroom, a personal spray for an evening walk, a coil only where airflow is guaranteed. Keep all units out of children's reach. Ventilate. Do not exceed the stated dose. Do not layer incompatible formulations. And if breathing difficulty lingers after leaving a treated space, move to fresh air and, if symptoms do not resolve within minutes, contact a physician.
None of this replaces the broader public-health measures — eliminating standing water, using bed nets in endemic zones, and seeking prompt medical care for fever lasting beyond two days — but it ensures that the small chemical shield on the shelf does not quietly become a source of its own low-grade harm.
This article is for informational purposes only and does not constitute medical advice. Consult a qualified physician for questions about any health condition or product interaction.
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