A guide to spiders: which can really harm us?

Spider science and complications

Spider venom, like that of jellyfish, is made of a number of enzymes. These are naturally occurring substances found within all living things, and act like molecular machines transforming chemicals to achieve some effect.

In the case of spider venom, these enzymes tend to damage human cells (cytotoxic) or kill them (necrotic.) Some forms cause paralysis (neurotoxic) and may venoms combine all three. It is the dose of the combined venoms that dictates the severity of symptoms. The real risk with these bites is infection or allergy.

Infection of a wound may become evident within hours to days of a bite. Spreading redness, pus, temperature swelling and feeling unwell may indicate a need for antibiotics. Feelings of sickness, chest pain, dizziness, shortness of breath, nausea, a fast heart rate or feeling very unwell may suggest an allergic shock and requires immediate hospital treatment. These complications of a bite are abnormality. Simple spider bites can be treated by cleaning the wound, simple painkillers and antihistamines to reduce itching/swelling.