Is it allergies or a cold? Pollen, dust, and what is making your nose run

If you have been blowing your nose every morning since you moved to Bangkok, you are not alone. I hear this from expats constantly. They arrive from Europe or North America expecting allergies to be a spring problem. Then they spend twelve months sneezing and assume it must be a series of colds. It is usually neither. Bangkok has its own set of airborne allergens, and they do not take a season off.

The good news is that most allergy symptoms are manageable once you know what is causing them. The frustrating part is that many people spend months on antihistamines that do not fully work, or avoiding triggers that are not actually their problem. Getting tested properly changes that. Here is what you need to know about allergy symptoms in Bangkok, how to tell them apart from a cold, and when it is time to stop guessing and come in.

Pollen allergy in Bangkok: why it behaves differently from back home

Most of my patients from Europe or North America expect pollen to be a spring problem. Birch trees, ragweed, high counts in April and May, then it settles down. Bangkok does not work like that.

Research conducted in Bangkok confirms that the dominant pollen allergens here are grasses and weeds, not trees. Nutsedge, para grass, and Bermuda grass are the main culprits. Because Bangkok’s tropical climate supports year-round grass growth, these pollens stay in the air across all seasons. Symptoms that started in February may still be going in September.

Your allergy test results from back home may not tell the full story either. Standard Western panels are built around temperate-climate allergens. If your panel never tested for nutsedge or para grass, you may have a sensitivity that was never picked up.

Bangkok’s air quality adds another layer. Fine airborne particles from traffic irritate the lining of the nose and airways, lowering the threshold at which pollen triggers a reaction. Even a moderate pollen count on a high-pollution day can produce symptoms that feel disproportionately severe. It is a double hit that is uniquely Bangkok.

Dust allergy: symptoms, triggers, and treatment options

Dust mite allergy is the most common indoor allergy I see here, and Bangkok’s warm, humid climate is almost perfect for dust mites. If your nose runs every morning when you wake up but clears once you have been out of the apartment for an hour, dust mites in your bedding or mattress are a strong suspect.

Symptoms include sneezing, a blocked or runny nose, itchy or watery eyes, and sometimes a dry cough. They are often worst first thing in the morning or after time in bed. Some patients also react to cockroach allergen, which is relevant in Bangkok, and mould spores that build up during the rainy season.

Avoidance measures help but rarely solve the problem entirely. Washing bedding weekly in hot water, using allergen-proof mattress covers, and running a HEPA air purifier in the bedroom all reduce the allergen load. They are worth doing, but they are not a substitute for treatment.

For moderate to severe symptoms, I recommend a nasal corticosteroid spray used daily. It reduces inflammation over time with consistent use and has strong evidence behind it as a first-line treatment. Antihistamines help with sneezing and itch but do less for congestion. For patients who want a longer-term solution, allergen immunotherapy, which gradually desensitises your immune system to the trigger, is something we discuss after formal allergy testing.

Nasal allergy: what causes a persistently blocked or runny nose?

Allergic rhinitis simply means inflammation of the nasal lining caused by an allergen. When it happens year-round, we call it perennial allergic rhinitis, and it is extremely common in Bangkok.

The nose reacts to an allergen by swelling, producing mucus, and triggering sneezing. Postnasal drip, where mucus runs down the back of the throat rather than out the front, is a common complaint. Patients describe it as a constant need to clear the throat or a mild cough that will not go away. It often gets misread as a chest infection.

Nasal corticosteroid sprays are the cornerstone of treatment. They need to be used daily and consistently, not just when symptoms are bad. Most patients notice real improvement within one to two weeks. Antihistamines help with breakthrough sneezing and itch. Decongestant sprays give fast relief but should not be used for more than a few days at a time.

If nasal symptoms are affecting your sleep or your ability to function, do not just push through. Untreated allergic rhinitis can contribute to sinus infections, middle ear problems, and can make asthma harder to control. Getting on top of it early makes a real difference.

Allergies vs cold: how to tell the difference

This is the question I get asked most often. Here is how I think about it.

Itching is the clearest sign that something is allergic. A cold does not make your eyes itch or your nose itch inside. If you are rubbing your eyes constantly and your nose itches before you even sneeze, that points strongly to an allergic response. Fever, on the other hand, points toward infection. Allergies never cause a fever. If your temperature is above 37.5 degrees Celsius alongside nasal symptoms, you are dealing with an infection.

Timing also matters. A cold starts, worsens over a few days, and resolves within one to two weeks. Allergy symptoms can appear quickly after allergen exposure and last for weeks or months without resolving. Allergy nasal discharge is usually clear and watery. A cold can start that way but often turns yellow or green as the infection progresses.

In Bangkok, poor air quality can irritate the airway in ways that look a lot like both. If you are not sure what you are dealing with after two weeks of symptoms, stop guessing and get assessed.

When to see a doctor about allergy symptoms in Bangkok

Most mild allergy symptoms can be managed with over-the-counter antihistamines to start. But there are clear points where you need to come in.

If your symptoms have lasted more than two to three weeks and are not improving, that is a signal to get tested. If symptoms are affecting your sleep, your work, or your ability to exercise, you need a proper treatment plan rather than another round of pharmacy guesses. If you are using a decongestant spray more than a few days a week, that is a problem in itself, as it can make congestion worse over time.

The bigger concern is the link between untreated allergic rhinitis and asthma. Persistent nasal allergy that goes unmanaged can eventually affect the lower airways. If you already have asthma and your control has deteriorated since arriving in Bangkok, an unidentified allergen may be driving it.

At Doctor Bangkok, we run either a skin prick test or a specific IgE blood test using a panel that includes Bangkok-relevant tropical allergens. Results guide a treatment plan tailored to what is actually triggering your symptoms here. You can find out more about our allergy testing and treatment and book online.

DR Ponlawat

Dr. Ponlawat Pitsuwan is a physician at Doctor Bangkok, a private clinic in central Bangkok. He sees expats, residents, and medical tourists for general medicine, wellness consultations, and IV therapy. His focus is straightforward, evidence-based care delivered in plain language.