Do not rely only on the internet. Consult your family doctor or community nurse.
There are five main health problems arising from a wasp sting:
Initial pain which can feel quite severe, especially to a child. The pain is much worse than pain from nettle stings or injections for immunisations. Personal experience is that the pain is very bad for around 30 to 40 minutes if not treated and then usually begins to fade. Treatment can instantly reduce pain sensations to minimal.
Local swelling at, and nearby, the wasp sting site. Untreated this can be very marked swelling. The swelling can cause pain itself so for example a badly swollen hand will hurt for many hours, long after the pain of the sting has gone. Swelling in itself is not usually harmful unless an eyelid becomes so puffy that there might be pressure on the nerves at the back of the eye (this needs prompt medical attention), or the airway is affected. Stings to the lip, mouth, inside or outside of the throat all need to receive prompt medical attention if swelling begins to develop. Swelling on a hand might cause a ring to cut blood supply off – so rings should always be removed when the sting is on the hand.
Infection of the sting site need not occur if proper care is taken. Although wasps visit dirty places like dustbins, rubbish bins and compost bins the only part in contact with you is the sting which had been held inside the wasp. It seems unlikely the sting would carry much in the way of infection. If the wasp stings through dirt on your skin due to the whatever you were doing prior to the sting, for example gardening or cleaning your dustbin then infection is more likely. Any scratching of the irritated site may also lead to infection. Simple hygiene measures immediately and good aftercare to minimise scratching greatly reduce the risk of infection.
Severe systemic allergic reaction (anaphylaxis). This is a very serious situation which can be life threatening. Statistically this occurs rarely and the even more rare chance of it causing death are mathematically less than your chance of winning a large amount of money on the lottery (In England 8 people in the whole year in 2004 and 2 people in one month in August 2006). No-one knows when their next sting may be the one to cause this serious total body reaction to a wasp sting. Symptoms and collapse can occur suddenly within the hour of the sting and so extremely prompt emergency medical care is required within 20 – 40 minutes of allergic reactions starting.
Fear of wasps in case of future stings and serious reactions. This fear can cause people to get stung again due to their reactions when a wasp is near them and can even cause other injury due to road traffic collisions if a wasp enters a car during driving. As it is actually very easy to avoid stings this fear can be minimised by developing understanding of how wasps live and what they want when they are near us. It should be very easy to become less fearful by reading through this website
Wasp sting aftercare is something you need to know about before you or your child gets stung. In the time it takes you to read this information severe reactions may have occurred and so it is better to have a thorough prior understanding of what to do and how to recognise and prevent problems occurring. Just like scalds with very hot water, prompt first aid for wasp stings is vital and can reduce the subsequent health problems.
There are some government organised information websites about what to do about wasp stings and as a health care professional I must advise you to use those sites as your main source of information and guidance. Currently excellent examples of these sites are called NHSDirect and PatientUK. There are links to their websites below (put stings into the search facility on their home page). Advice on those sites is updated more regularly than this website and their advice will always take into account any new evidence. If your Health Centre has a website you should also check what your family doctor advises for wasp sting treatment.