Tarantula Bites and Scorpion Stings Just How Dangerous Are They?

The Full Story

Tarantulas and scorpions, the stuff of nightmares, are loathed by many and admired by some. Popular in Hollywood movies and YouTube videos, these desert dwellers also have starring roles in Zuni Native American and Greek mythologies. Both tarantulas and scorpions have received their fair share of negative press in Internet folklore resulting in exaggerated and inaccurate concerns about their danger to humans.

Tarantulas can be found throughout the US with many species living in the dry areas of the western states. Scorpions can be found in warm climates throughout the world, but in the US their habitat is primarily the Southwest desert areas. Both tarantulas and scorpions are arachnids as are ordinary spiders. They have an outside shell instead of an inside skeleton, segmented bodies, and 4 pairs of legs. Tarantulas have 8 eyes, are large and hairy, and have fangs. Scorpions have a front pair of pinchers and a tail that contains venom sacs and a curved barb (think stinger). Tarantulas bite; scorpions sting.

Tarantulas

While many people are terrified of spiders, tarantulas are sometimes kept as pets. When handled gently, tarantulas pose little risk. When threatened, the spider will bite and can also release a cloud of irritating hairs. The bites usually leave fang marks and are often painful. The pain is described as throbbing and can last for hours. Fever, nausea, and vomiting occur rarely. In general, the effects from tarantula bites are mild. A greater health risk is from contact with the spider's hairs. Contact of the hairs with the skin causes lots of inflammation including pain, redness, itching, and swelling that can last for weeks. The hairs can also get into the eyes and cause pain, redness, sensitivity to light, and other eye problems. The eye discomfort has been described as like having fiberglass particles in the eye. The hairs can get stuck in the eye for a long time.

There is no antidote for tarantula bites, but the pain can be managed with cool compresses (such as ice packs) and over-the-counter pain relievers (such as acetaminophen or ibuprofen). All bites should be washed well with soap and water. Hairs stuck in the skin can be removed using a sticky tape such as duct tape. Inflammatory skin reactions can be managed with topical corticosteroids (such as hydrocortisone cream) and oral antihistamines (such as diphenhydramine). The skin irritation usually responds well to over-the-counter treatments but sometimes requires prescription strength medicines like prednisone or other corticosteroids. Hairs stuck in the eyes might need surgical removal, but sometimes the hairs are so small that removal is difficult. Inflammatory eye reactions can be managed with corticosteroid eye drops.

Scorpions

Scorpions come in a variety of colors, shapes, and sizes. They often blend into their environment during daylight but will glow under a black light at night. The toxicity caused by a scorpion sting differs depending on the kind of scorpion involved. There are several areas of the world where scorpion stings cause serious toxicity. Fortunately, most of the scorpions found in the US are much less dangerous but they can still inflict painful stings. The pain occurs immediately and is often described as stinging or burning, although sometimes a tingling or numb sensation happens. Other possible effects at the sting site include redness, swelling, and a scab. The most dangerous species found in the US is the Centruroides exilicauda (formerly known as Centruroides sculpturatus), commonly called the bark scorpion. This species primarily lives in Arizona but can also be found in parts of California, Nevada, New Mexico, Texas, and Utah. In addition to causing a painful sting, the bark scorpion can sometimes cause abnormal muscle activity like muscle twitching, unusual eye movements, slurred speech, or difficulty swallowing and breathing. Agitation, high blood pressure, and changes in heart rate can develop. These effects usually happen quickly, can worsen over a few hours, and can last for several hours. Serious toxicity is typically limited to very young children. Death from a scorpion sting is very rare and has not been reported in the US for almost 50 years.

Treatment for all scorpion stings includes washing the site with soap and water. A tourniquet should never be used. Pain from scorpion stings can usually be managed at home with over-the-counter pain relievers. Initial management of a scorpion sting at home is appropriate even if it is known to be a bark scorpion, but call Poison Control to help you through it. Pain that is not relieved with home treatment or the development of body-wide effects should be managed in an emergency room because prescription pain relievers, muscle relaxants, or other medications might be needed. Antivenom is available in the US to treat serious envenomation from Centruroides species, but life-threatening side effects can happen and it is very expensive and not stocked by many hospitals.

If you suspect someone has been bitten by a tarantula or stung by a scorpion, wash the area well with soap and water, then check the webPOISONCONTROL^® online tool for guidance or call Poison Control at 1-800-222-1222.

Karen D. Dominguez, PharmD
Certified Specialist in Poison Information