Most of the time, if left alone and treated with respect,social wasps will not pose a problem. However, if one is unlucky enough to accidentally disturb a nest, this can lead to a mass attack. So it is always better to know what to do if stung.
Unlike a bee,wasps can sting over and over,because their sting is not barbed like a bee's. Though their venom on its own is probably not more dangerous than a bee,a sting from a social wasp, especially those of the genus Vespa (hornets),can hurt a lot more.
A single sting usually produces intense local pain and swelling, and later, local itching. It should not cause anything more. In this case,all that is needed is to apply antiseptic and treat with ice. In the field, always carry antiseptic pads containing 75% isopropyl alcohol - these work wonders for disinfecting and relieving some of the pain. Many traditional remedies are suggested for insect stings; most of these do not do any harm, but are not necessary. Simple disinfection is sufficient.
However,there is always the danger of an allergic reaction. Symptoms of an allergic reaction include breathing difficulty, generalised itching, rash, rapid heartrate, chest tightness, wheezing, light-headedness or dizziness, headache, abdominal pain, nausea/vomiting. In this case, if such symptoms start, in fact, if any other symptoms besides local reactions occur, seek medical treatment immediately as it can be fatal. Also,a sting in the mouth or throat can be dangerous,so medical treatment is also advised.
This is my right hand after receiving four stings from the hornet Vespa velutina. Such local swelling is not uncommon with wasp stings, but is not a cause for concern. Systemic effects, however, must not be taken lightly.
Single stings are rare and can easily be avoided by not hitting or catching a wasp with bare hands.
If attacked by a swarm,the important thing is to leave the area as quickly as possible. If the area permits,run as fast as possible until most or all of the wasps are far behind or have stopped chasing. Try to get indoors. Some sources suggest jumping into a body of water as an alternative, or taking off articles of clothing where feasible and swinging them both to swat down the insects and to distract them away from the face and neck. Personally, I have no idea if it will work. If all of these are not possible, lie flat on the floor and cover head and neck with hands. Also, try to pull a portion of clothing over your face and neck to avoid being stung there. Yet another method that I find works quite well is to turn sharply or run round a corner. However, this may be less effective with a whole swarm.
Always seek medical attention after being attacked by a swarm because the number of stings means that a lot of venom might have been injected into the body system.