Introduction A CDC report shows that in 1994, there were 9,418 spider bites reported in the U.S. with 82 (0.9%) of them being attributed to tarantulas. Spider bites are not required to be reported by law and these numbers are the result of people calling poison control centers for advice, so the actual number may be higher. While there is little or no documented medical evidence regarding the medical significance of tarantula bites, all tarantulas are venomous and their bite can cause a local and/or systemic reaction. If you plan on keeping and especially handling tarantulas you should be familiar with some basic first aid procedures in the unlikely event of a bite. It is important to note that the information presented here is a very basic overview and is not intended to be a replacement for qualified medical care.
Reactions to venom will vary from person to person and are affected by a number of factors including the amount of venom injected, the size and general health of the victim, and the toxicity of the venom. It is estimated that 5% of people will have an allergic reaction to (any) venom and of that group a small percentage will develop anaphylactic shock.
Localized Reactions Following a tarantula bite expect, at the very least, to see some local reactions:
Skin weal at the bite site
Immediate treatment should be to wash the area with soap and water and apply cool compresses to the site. A paste made from baking soda and water and applied to the site may help decrease the severity of the local reaction. Topical cortisone or Benadryl creams may also help to with itching or irritation. You should also observe for signs of an allergic or anaphylactic reaction. If you haven't had a tetanus shot in the past 5 years, contact your doctor to decide whether you should receive an update. If you haven't had a tetanus in the past 10 years, now is a good time to get one.
Suctioning style snake bite kits are considered ineffective at withdrawing venom from a site and under no circumstances should you attempt to suck venom out with your mouth. Over the next week or so be sure to keep the area clean and apply an antibiotic ointment such as Bacitracin, or Polysporin and watch for infection.
Common Signs of Infection
The site becomes red and warm to the touch.
Red streaks near the site.
Pain or yellowish discharge from the site.
Fever, chills, body aches.
Bumps in the armpits or groin.
Allergic reactions and anaphylactic shock are primarily caused by the release of immunoglobulin E (IgE). This antibody mediates the body's allergic response by attaching to the body's mast cells, stimulating the release of histamine and heparin. Histamine has many effects on the body including bronchoconstriction, vasodilation and increased gastric motility. While uncomfortable, these reactions serve to accelerate the deactivation and elimination of the allergen. The signs and symptoms of an allergic reaction include:
Headache is a common complaint as are anxiety and restlessness.
A rash or urticaria (hives) along with a warm or itchy feeling caused by vasodilation and increased permeability of the capillaries.
Sneezing, coughing and/or wheezing are early signs that should be watched It can potentially progress to neck and throat tightness.
The gastrointestinal system responds aggressively to the release of histamine. Nausea, vomiting, diarrhea and abdominal cramps may present as the body tries to rid itself of the offending toxin.
Wash the bite with soap and water, and apply cool compresses. Minor reactions generally respond well to over-the-counter antihistamines such as diphenhydramine (Benadryl) and will usually resolve anywhere from a couple of days to more than a week.
If you experience any chest tightness, difficulty breathing or a lot of hives, you should be evaluated by a physician. The physician may opt to give epinephrine 1:1000 which decreases the capillary permeability and opens the airways. Steroids may also be prescribed for long term maintenance. Steroids decrease inflammation and suppress the body's immune response. If you have an allergic reaction, there is roughly a 60% chance of a similar or worse reaction if bitten again.
Anaphylaxis can best be described as a runaway allergic reaction. In an anaphylactic reaction the person's airway can be rapidly obstructed by swelling, the blood pressure can drop sharply and convulsions or cardiac arrest may ensue. This is a true medical emergency and the person must be transported to a hospital immediately, preferably by ambulance. DIAL 9-1-1, or the number used to activate your local emergency medical service.
Treat the local reaction as discussed above. Keep the affected extremity lower than the level of the heart. You might also apply a constricting band between the bite and the person's heart. This should only be a bit tighter than a watch band to decrease the flow of lymph.
Do not apply an arterial tourniquet!
Persons predisposed to anaphylaxis may be wearing a medic alert bracelet or necklace and may carry a kit containing epinephrine 1:1000. The person and family members should be trained in the indications for and use of the kit.
If someone is allergic to bee or wasp stings it doesn't mean that they will automatically have an adverse reaction from tarantula venom. While tarantula venom causes reactions that resemble bee venom, chemically it is very different.
While tarantula bites have not proven to be a significant medical problem, care and common sense are the rule when handling and caring for a bite. If you have any concerns regarding an allergic reaction to a bite, it is best to err on the side of safety and seek medical advice from a qualified physician.
It's always a good idea to...
Have the number to the Poison Control Center posted near your telephone.
Know how to activate your local emergency medical services.
Take a course in CPR.
Think and act safe when working with or showing your spiders.