Quick answer. A runny nose (rhinorrhoea) is excess nasal discharge, most often from a cold or allergic rhinitis, and usually settles on its own or with simple treatment. One-sided clear fluid after a head injury or one-sided bloody discharge are warning signs that need an ENT review.
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A runny nose, known medically as rhinorrhoea, is one of the most common complaints there is. It happens when the lining of the nose produces more mucus than usual, often as a reaction to infection, allergens or irritants. In Singapore, colds and allergic rhinitis triggered by house dust mites, and occasionally haze, are frequent culprits.
Most of the time a runny nose is harmless and clears up by itself. This guide explains the common causes, how a persistent runny nose differs from a blocked nose, what treatments help, and the small number of warning signs, such as one-sided clear fluid after a head injury, that mean you should see an ENT specialist.
At a glance
| Cause | Typical features | Usual course |
|---|---|---|
| Common cold | Clear then thicker mucus, sore throat, mild fever | Settles in about a week to ten days |
| Allergic rhinitis | Clear watery discharge, sneezing, itchy eyes | Recurs with allergen exposure |
| Sinusitis | Thick discoloured mucus, facial pain or pressure | May need treatment if persistent |
| Vasomotor (non-allergic) | Triggered by temperature change, smells, spicy food | Ongoing, no clear allergy |
| Irritants or haze | Watery discharge with exposure | Eases when exposure stops |
What is a runny nose (rhinorrhoea)?
A runny nose, or rhinorrhoea, is the discharge of excess fluid from the nose. The lining of the nose normally makes mucus to keep it moist and to trap dust and germs; when it is irritated or inflamed, it produces far more, which then drips from the nostrils or runs down the back of the throat (post-nasal drip).
The colour and consistency can give clues. Clear, watery discharge often points to a viral cold in its early stage or to allergy, while thicker yellow or green mucus can occur later in a cold or with a sinus infection. A runny nose is different from a blocked or stuffy nose, although the two often go together. It is usually a temporary nuisance rather than a sign of anything serious.
Symptoms & associated signs
A runny nose may come on its own or with other symptoms depending on the cause. You might notice:
- Clear, watery or thicker discoloured nasal discharge
- Sneezing
- A blocked or stuffy nose
- Itchy nose, eyes or throat, especially with allergy
- Post-nasal drip, where mucus runs down the back of the throat
- A mild cough or throat irritation
- Facial pressure or pain over the cheeks or forehead with sinusitis
- Sore throat, mild fever or body aches with a cold
Allergic causes tend to bring sneezing and itchy, watery eyes, while infections more often bring fever and feeling unwell.
Causes & risk factors
Common causes of a runny nose include:
- Colds and other viral infections, the most frequent cause
- Allergic rhinitis, triggered by allergens such as house dust mites (very common in Singapore homes), pollen, pet dander or mould
- Sinusitis, inflammation or infection of the sinuses
- Vasomotor (non-allergic) rhinitis, where the nose over-reacts to temperature changes, strong smells, spicy food or fumes without a true allergy
- Irritants such as cigarette smoke, pollution and haze
- Crying, cold weather, or hot or spicy food
Risk factors include a personal or family history of allergy, asthma or eczema, frequent exposure to allergens or irritants, and close contact with people who have coughs and colds.
How it's diagnosed
Most cases of a runny nose need no special tests and are diagnosed from your symptoms and a simple examination of the nose. A doctor will ask about how long it has lasted, the colour of the discharge, triggers, and whether you have itchy eyes, fever or facial pain, which helps separate a cold from allergy or sinusitis.
If symptoms are persistent, one-sided or unusual, an ENT specialist may examine the nose more closely with a nasal endoscope (a thin camera) to look at the lining and sinuses. Allergy testing, such as a skin prick test or blood test, can identify triggers in suspected allergic rhinitis. Imaging such as a CT scan of the sinuses may be used for chronic sinus problems or to investigate one-sided symptoms.
Treatment options
Treatment depends on the cause. For a cold, rest, fluids and time are usually all that is needed, with simple remedies such as steam inhalation and saline nasal sprays or rinses to ease symptoms. Antibiotics do not help viral colds.
For allergic rhinitis, the mainstays are avoiding triggers where possible (for dust mite allergy, regular washing of bedding and reducing dust at home), antihistamines, and steroid nasal sprays, which are very effective at reducing inflammation. For sinusitis, treatment may include nasal rinses, decongestants for short-term use, steroid sprays and, where a bacterial infection is confirmed, antibiotics. Vasomotor rhinitis is managed by avoiding triggers and using certain nasal sprays. If symptoms are persistent or do not respond, an ENT specialist can review the diagnosis and consider further treatment.
When to see a doctor & which specialist
A runny nose is rarely an emergency, but certain features need prompt medical attention. Seek urgent care, and call 995 or go to A&E if needed, for a persistent watery, clear discharge from one nostril after a head injury, as this can rarely be cerebrospinal fluid (a CSF leak). See an ENT specialist soon for a one-sided bloody or blood-stained discharge, a persistent one-sided blocked or runny nose, or a runny nose with persistent facial pain, swelling or numbness.
You should also see a doctor if a runny nose lasts more than about ten days without improving, keeps coming back, comes with a high fever, or significantly affects your sleep or daily life. An ENT specialist can examine the nose, arrange allergy testing or imaging, and tailor treatment. Find one through our directory of ENT specialists in Singapore.
Related guides
- Best ENT Clinics in Singapore — our editorial shortlist
- ENT clinics directory
- Angiogram
- Heart murmur
- Heart bypass (CABG)
- Vasovagal syncope
- Tonsillectomy
Sources
Part of our Ear, nose & throat guides · Browse all health topics