Yellow Sac Spider Bite: Pictures, Symptoms & First Aids

There are a variety of sac spiders found in North America. The yellow sac spider is one of the more common specie seen in and around people’s homes. These very tiny spiders are often hard to identify but take it from someone with experience with these spiders – they can pack a big punch when their fangs latch on to the skin. Although painful, basic first aid for its bites is usually all that is required for treatment.

The spider is very small. Examining one up close for distinguishing characteristics may take a magnifying glass. The body of an adult yellow sac spider is approximately one-quarter inch long and is a light brown/tan color or it may have a yellow-tint to the coloring. Many believe that it is a definite “yellow” which isn’t always the case. Because of their color range, the yellow sacspider is often misidentified as a brown recluse.

At first glance, they may look like a harmless brown spider or the dreaded brown recluse. The two-part body has a sac-like back end and the head has eyes and fangs. There are two distinguishing characteristics when trying to identify these spiders – the eyes and front legs.

Many times people who encounter these spiders may smash them until their body parts are no longer recognizable. The most important part of the spider for identification purposes is the upper part. On the head, the spider has two rows of eyes, one row on top of the other, with four eyes in each row – yes, that’s a total of 8 eyes! Another characteristic of the body is the front legs which are somewhat longer than the other legs. They are a lot longer than the very back legs.

The Bite
The intensity of the yellow sacspider’s bite has been described anywhere from a pin prick to an intense sting like that of a hornet. From personal experience, the bite feels like a painful bee sting. The venom of the yellow sac spider contains cytotoxin – the same as the brown recluse spider but not as potent. While the bite is not as dangerous as the brown recluse, it can still cause a variety of symptoms – especially pain. Here are pictures of bites as below:

Depending upon the severity of the bite, victims most often just experience pain at the location of the bite. Swelling and redness often follow shortly after. In severe cases, victims may experience a fever, headache, dizziness, and nausea. In the most serious cases, a person may go into shock especially if they are highly allergic to the venom.

In rare cases, the skin may begin to die at the area of the bite which is also a common occurrence with brown recluse spider bites. Yellow sac spider bites are often mistaken for brown recluse spider bites. While these two spiders have a lot in common, it’s important to remember that the bite from a yellow sacspider is not as serious.

First Aid

There are a number of yellow sac spider species, but all of them involve a rather nasty bite that requires some care to make sure that it doesn’t become infected. Thankfully the bites are not fatal and do not cause a great deal of concerned unless one is allergic to them.

Identifying the spider

Whenever possible it is a good idea to catch the spider that is responsible for your bite. This way you can take it in for identification if you need to see a medical care practitioner. With the yellow sacspider you are looking at a spider that is about 1/2″ to 1″ in size. It is smooth and its abdomen region is large and rather bulbous in appearance. It is usually tan or yellowish in appearance, but it can be a darker brown or even a pale yellow or cream. It is a very smooth spider and has three rows of eyes. The difficulty with the spider is that it doesn’t really have any distinguishing marks that set it aside from other spiders.

Identifying the bite

Often times the bite feels like a sharp sting. For some people this is very mild, but most people who know that they have been bitten often report it feeling much like a wasp sting. However, when a spider isn’t present it is hard to know what caused the bite. This is especially true if you were bitten in the night and now have a red mark. While you may not know for sure whether or not the bite was caused from a yellow sac spider bite some basic care for the bite will help and make sure that it doesn’t get infected.

Wash the area

You should wash the area really well and make sure that you keep it clean on a regular basis. This usually means washing the area once or twice a day.

Antibacterial cream

You will want to apply an antibacterial cream to the bite. This will help to keep the area from getting infected which is the number one concern with a yellow sac spider bite.

Avoid itching and popping

It is important to try and avoid itching the spider bite. If a lesion or puss filled blister breaks out on the surface of the skin you want to avoid popping this. That increases the risk of infection and can cause additional pain. It is best to keep it covered to avoid damage to the area as well.

Elevate the area

If you are having a fair amount of swelling the best thing you can do is elevate the area. This will help reduce the swelling and in turn will make your discomfort less.

Seek medical attention

As long as you are keeping the wound clean and avoiding infection most yellow sacspider bites don’t require medical attention. However, if you are feeling dizzy, nauseous, experiencing chills, have a fever, or have a headache within eight hours of the bite. These are signs that you may be allergic to the spider bite and it is best to go and see a doctor. If you have any other concerns you may also want to visit the doctor just to be sure.


In most cases healing is very quick. If there isn’t a legion or blister you can expect the bite to be gone in a couple of weeks. Healing time for a legion or blister caused from a yellow sac spider bite is about 8 weeks. It is best if you make sure that you keep the area clean during the entire healing process. It is also a good idea to keep antibiotic ointment on the blister for the entire time that it is there as well. Blistered bites are much more likely to get infected and taking good care of them can prevent issues later on.

These bites are often uncomfortable, but they rarely have complications and rarely cause serious allergic reactions. Make sure that you take good care of your spider bite to avoid infection. Remember that it is important to try and avoid itching the bite!