Black Widow Bite

A black widow bite often feels like a pinprick and leaves only faint marks, but within an hour it can cause spreading muscle pain, cramps and sweating, a reaction called latrodectism. It is rarely dangerous and most people are better within 1–2 days. Call Poison Control at 1-800-222-1222 right away, and go to an ER for severe pain, breathing trouble, or if the person bitten is a small child, older, pregnant or has heart disease.

How black widow bites happen

Black widows are not aggressive. Penn State Extension notes nearly all bites come from adult females, especially those guarding egg sacs; males and young spiders can't pierce human skin. Bites happen when a female is pressed against skin: putting on a glove, boot or piece of clothing stored in a garage, reaching under a deck or into a woodpile, sitting on outdoor furniture, or using an outhouse or shed. Penn State estimates about 2,200 black widow bites a year in the US. See black widow spider for where they hide.

What does a black widow bite look like?

The skin is the least dramatic part:

• one or two small red puncture marks, often too faint to see;
• slight swelling and redness; sometimes a pale ring with redness around it (a target look);
• sweating and goosebumps around the bite, sometimes on other parts of the body as well. This is unusual for other bites and a useful clue.

There is usually no blister, no ulcer and no dead tissue. If a wound blisters, oozes, or turns dark and sunken over days, that points to something else, most often a bacterial skin infection, not a black widow.

Black widow bite symptoms

Black widow venom (alpha-latrotoxin) makes nerves release signals nonstop, so muscles fire and cramp. A typical timeline, based on Poison Control and Penn State Extension:

Other possible signs: headache, tremors, rapid heartbeat, puffy eyelids and trouble breathing. A board-hard, painful belly can mimic appendicitis, and doctors have mistaken it for that when nobody mentioned a bite.

Can a black widow kill you?

Very rarely. Poison Control describes a review of more than 15,000 US black widow exposures with no deaths. About half of those people were managed at home and about 10% were admitted to a hospital. Penn State Extension notes no US deaths recorded since 1983. Severe cases do happen, mostly in small children (Poison Control describes a 3-year-old who needed a breathing tube), and older adults, pregnant people and anyone with heart disease or high blood pressure are also at higher risk.

What people who dealt with it say

We read first-hand accounts in r/AskDocs and r/spiderbro. A few patterns stood out:

• People rarely realize it's a bite at first. One person bitten by a female hiding in a compression wrap stored in the garage thought the velcro was scratching her hip. Another, bitten on the foot in the yard, thought she'd torn a ligament. The pain was 10/10, spread, and came with uncontrollable shaking.
• The worst is usually overnight. Several accounts describe the pain peaking in the first night, then being able to walk normally and feeling only sore by the next day. One reported feeling "out of it" for about a week with a large welt.
• Timing matters for treatment. In one r/AskDocs thread a medical responder explained that once the worst has passed, antivenom is no longer an option and the only treatment left is pain control, so if the pain is severe, go in early.
• Goosebumps are a giveaway. The same thread pointed out that widow venom often causes goosebumps, sometimes on limbs away from the bite, which helps tell it apart from, say, stepping on a bee.
• Lingering spots happen. One person with an ER-confirmed bite had the site flare up every few months for over a year. A medical responder replied that persistent bite reactions can last months, so ongoing problems are worth a dermatologist visit.
• Necrotic "black widow bites" are usually infections. In a viral thread about a blistering, blackening wound blamed on a widow, the top replies were that MRSA is often mistaken for spider bites and that antibiotics were needed.

First aid for a black widow bite

1. Move away from the spider. If it's safe, take a photo or trap it in a jar for ID.
2. Wash the bite with soap and water.
3. Apply a cold pack wrapped in cloth, 10 minutes on, 10 off.
4. Keep the limb still and raised if you can.
5. Take an over-the-counter pain reliever, following the package directions, if you're not going straight to an ER.
6. Call Poison Control (1-800-222-1222, free, 24/7). They'll tell you whether home care is enough.
7. Do not cut the bite, suck out venom, or apply a tourniquet or heat.

Check that your tetanus shot is current; Poison Control and NIOSH both recommend it after spider bites.

When to see a doctor

Go to an ER or call 911 if:

• pain spreads beyond the bite or muscle cramps begin and over-the-counter pain relievers don't control it;
• there is trouble breathing or swallowing, chest pain, or a pounding headache;
• the person bitten is a child, older adult, pregnant, or has heart problems or high blood pressure;
• symptoms get worse instead of better after a few hours.

What hospitals do: manage pain and muscle spasms with medication, monitor blood pressure and heart rate, and, for severe cases, consider antivenom. Poison Control notes the antivenom works but is made from horse serum, can cause anaphylaxis, and isn't available at every hospital, so it's kept for symptoms that other treatment can't control.

Is it really a black widow bite?

Severe, spreading muscle cramps with sweating and few skin changes fit a widow. A painful bump that blisters, oozes or ulcerates over days fits other causes: infection, a brown recluse bite in recluse country, or another insect. If you saw the spider, compare it with black widow look-alikes: false widows (Steatoda) are common and their bites usually cause only local pain, and brown widow bites tend to be milder. For other spiders, see spider bites.

Preventing bites

Wear gloves for yard work, woodpiles and cleaning sheds. Shake out shoes, gloves, boots and clothing kept in garages, or store them in sealed plastic bags as NIOSH recommends. Keep stored items off the floor, check under outdoor chair seats and deck-box lids, and clear webs from play equipment. See how to get rid of spiders.