Ragweed pollen allergy
Ragweed pollen allergy, peaking in late summer and autumn.
About ragweed pollen allergy
Ragweed is a weed that produces highly allergenic, wind-borne pollen, mainly in late summer and autumn, from around August into October. It is a major cause of autumn hay fever in North America and parts of continental Europe. In the UK it is currently less established, so it causes fewer problems here, but it is spreading in Europe and can affect UK residents through imported pollen and travel, making it worth recognising. When a sensitised person inhales ragweed pollen, the immune system produces IgE antibodies against its proteins, driving an allergic reaction. A single ragweed plant can release very large amounts of pollen, which is why it is such a potent late-season trigger.
The usual presentation is seasonal allergic rhinitis, with sneezing, a runny or blocked nose and itchy, watering eyes in late summer and autumn, extending the hay-fever season. As with other pollens, exposure can worsen asthma and eczema in those prone to them. Ragweed is also linked with pollen-food (oral allergy) syndrome and can cross-react with mugwort and with certain foods such as melon and banana, causing an itchy mouth in some people. Symptoms are usually not life-threatening but can be persistent and disruptive.
Seasonal avoidance measures help, such as checking pollen forecasts, keeping windows shut at peak times and washing off pollen. Diagnosis uses skin-prick or specific-IgE tests. Treatment follows the usual ladder of antihistamines and steroid nasal sprays, with immunotherapy considered for selected cases. See a GP if symptoms are hard to control or affect sleep and daily life.
Common triggers
- Ragweed pollen and products containing it
Symptoms
- Sneezing and a runny or blocked nose
- Itchy, red or watery eyes
- Itchy throat, nose or ears
- Coughing or wheezing
- Worsening of asthma
Avoidance & management
- Reduce exposure to the trigger where possible
- Keep windows closed during high-exposure periods
- Use air filtration and wash bedding regularly
- Shower and change clothes after exposure
- Use prescribed antihistamines, nasal sprays or preventers
Sources & references
Allergy safety: what everyone should know
Mild-to-moderate reaction signs
- Itching, hives or a raised rash
- Swelling of lips, face or eyes
- Tingling mouth, sneezing, runny nose
- Stomach pain, nausea or vomiting
Anaphylaxis — call 999 (UK) or 112 (EU) immediately
- Difficult or noisy breathing, wheeze, persistent cough
- Swelling of the tongue or tightness in the throat
- Dizziness, collapse, pale and floppy (young children)
- Use an adrenaline auto-injector (e.g. EpiPen) at once if prescribed, then call an ambulance even if symptoms improve
Allergy or intolerance? A true allergy involves the immune system and can escalate quickly; an intolerance (e.g. lactose intolerance) is unpleasant but not life-threatening. The symptoms overlap, so self-diagnosis is unreliable.
Getting tested: home-testing kits based on IgG are not diagnostically valid. If you suspect an allergy, ask a GP for referral to an allergy clinic for skin-prick or specific-IgE testing and a supervised food challenge where appropriate.