Only a very small number of the larger species of British spiders have fangs capable of penetrating human skin. There have been a number of reports of people being bitten by spiders and false widows are often the focus of this, particularly in the media. However, it is difficult to obtain accurate evidence as those complaining of bites often do not see the spider but assume they are the culprit because of the absence of a bee or wasp. Alternatively, they only get a brief glimpse. Rarely is a spider captured and an accurate identification carried out.
Steatoda nobilis and occasionally Steatoda grossa have been implicated in bites on humans. A young woman in Worthing was recorded as being bitten by a female Steatoda nobilis (Snazell & Jones 1993, Bulletin of the British Arachnological Society Vol 9 164-167) and in 2009, there was a report of a woman from West Cumbria being bitten by a false widow spider which allegedly caused her to suffer from an allergic reaction. Indeed, it would appear that such a reaction is likely to be the most likely cause of a serious problem to humans as otherwise the bite has been compared to a wasp sting. In fact, when one considers the undoubtedly large number of people who are stung each year by wasps and bees, the risk of being bitten by a false widow spider must surely be relatively small. False widows are sedentary by nature, remaining in their webs and the males are only likely to wander when they are ready to mate. Being bitten is therefore likely to be the result of putting a hand into a web, handling one roughly or sitting or lying on one by mistake. Reports of bites by false widows are difficult to substantiate and often highly exaggerated by the media.
In summary, being bitten by a spider is very unlikely in this country in normal circumstances, and the effect of a bite is unlikely to be worse than being stung by a wasp or bee. A more serious problem is only likely to arise in the event of an allergic reaction, infection of the bite or if the person is already compromised by other health issues.
Nevertheless, if severe swelling or ulceration results from a suspected spider bite it is recommended that you see your doctor immediately or visit an Accident and Emergency Department.