Spider Bite Allergies and Toxic Reactions

Spiders get a lot of bad press. They look fearsome and dangerous, but few spiders can seriously hurt humans and animals. Even so, arachnophobia, an irrational fear of spiders, is widespread. And among people who experience allergic reactions to spider bites, that fear may be justified.

An allergic or anaphylactic reaction to a spider bite is uncommon, but it can occur, and when it does, it's a 911 medical emergency. So it's a good idea to recognize the symptoms of anaphylaxis:

· Hives, itching (urticaria)

· Shortness of breath, wheezing, coughing, hoarseness, feeling of fullness in the mouth or throat that may indicate that the airway is closing or narrowing

· Weakness, fainting, confusion because of inadequate blood flow to organs, also known as shock

· Nausea, vomiting, diarrhea, cramps

· Face, eyes, tongue, lips, ears, palms of hands, soles of feet and mucous membrane swelling (angioedema).

· Drop in blood pressure, fainting, and respiratory arrest. This is called anaphylactic shock and needs immediate attention or death may result.

What's the difference between allergic reactions and toxic reactions to spider bites? Toxic reactions can occur in anyone if there are multiple bites from any kind of spider, or if the spider is very poisonous. But few spiders fall into the toxic category. Most spiders are beneficial to the ecosystem as well as harmless to humans. The main exceptions are black widows, brown recluses, hobos and scorpions. As for tarantulas, many people are terrified of them because they're big and scary-looking, but they're actually very timid. Their bite is painful-like a bee bite-but harmless.

The difference between an allergic and a toxic reaction is that in the latter, there are no hives, nor is there difficulty breathing. Symptoms of a toxic reaction usually disappear in 48 hours. However, be aware that a spider bite may produce a combined toxic and allergic reaction, so get to an ER as soon as possible. Symptoms of a toxic reaction may include most of those listed above plus the following:

· Fever

· Swelling at the bite site

· Muscle spasms

· Headache

· Drowsiness

· Seizures (jerky movements)

· Shock

· Heart rhythm abnormalities

· Death

Depending on an individual's susceptibility to spider bites, physical reactions or infections can also occur that involve a large or small area of skin or a mucous membrane. These are not strictly allergic reactions but may require medical attention if they are still present after a week or there are red streaks indicating blood poisoning, pus, swollen lymph nodes, fever, chills or nausea.

The important point to remember about spider bites is that all spiders are poisonous, but in the vast majority of cases their poison is too weak to do any damage. The world is full of spiders quietly going about their business, most of them quite invisible. If you suspect or know you are allergic to spider bites, learn the symptoms of anaphylaxis and have a plan in place to get medical help, should you need it.