What Is a Spider Bite

A spider bite is actually a bite rather than a sting because these arachnids have jaws and fangs.

The lesions they cause are often confused with those of other insects or even with skin infections.

Although most spider bites are completely harmless and produce no symptoms in humans, there are some species that can cause conditions ranging from inflammation and itching to something more serious.

Some spiders have a powerful venom that can cause severe symptoms and, at times, endanger a person’s life. Two of the most venomous spiders often found in Mexico are the black widow and the brown recluse.

These arachnids don’t attack unless they feel threatened, but since they live in places without much activity, like bookcases, closets, or sheds, it’s possible for them to accidentally bite us if they feel threatened.

Types of Spider Bites

The types of spider bites are usually classified according to the effect of the venom produced by the species that bit the person. Although not all spiders are dangerous to humans, bites that can cause symptoms are typically divided into three main types:

• Non-venomous or mild-reaction bites: These are the most common. Most spiders do not have fangs strong enough to penetrate human skin, and their venom does not cause significant effects.
• Bites with a local necrotic effect: These are caused by spiders whose venom destroys tissues, such as the brown recluse. The bite is usually painless, but over time, a lesion appears and worsens.
• Bites with a neurotoxic effect: These affect the nervous system. One of the most representative spiders is the black widow. Although it is rarely fatal, it requires urgent medical attention.

Symptoms of a Spider Bite

Some people don’t even notice when they have been bitten by a spider and only perceive a small red mark, similar to a mosquito bite, which disappears on its own in a matter of days. In these cases, there is no significant pain, inflammation, or other symptoms that suggest a serious reaction. Therefore, no medical treatment is required beyond basic cleaning and observation.

But there are some situations where a spider bite can cause discomfort that is not serious. These include local redness, mild inflammation, itching, moderate pain, or a burning sensation. In some cases, blisters or small ulcers may also develop. Even so, these symptoms usually resolve in a matter of days with simple care, and antihistamine creams or analgesics can be used to combat the discomfort.

However, when a person has a spider bite that can cause severe or dangerous symptoms, there are several signs to consider. Depending on the type of spider and its venom, there may be severe pain, fever, necrosis, or respiratory problems, although this will vary depending on the type of spider bite.

If you have the following symptoms, go to your doctor or the ABC emergency room:

• You have intense pain throughout your body, especially in the abdominal area.
• The ulcerous lesion caused by the spider bite begins to spread and increase in size.
• You have difficulty breathing.
• In certain cases, when the person bitten is more susceptible to the venom of these spiders, the symptoms are magnified and can be fatal, especially when the affected people are children.

Black Widow

• Inflammation and intense pain in the affected area, radiating to the abdomen, chest, and back.
• Acute abdominal pain that is often confused with appendicitis.
• Nausea, vomiting, sweating, and chills.

Brown Recluse

Symptoms normally worsen after seven hours from the bite:

• Intense pain in the affected area and throughout the body.
• High temperature and chills.
• Necrosis in the tissues around the bite that slows down healing.

Diagnosing a Spider Bite

The diagnosis of a spider bite can be easier if the person directly sees the animal bite them or can clearly identify the species. For example, the black widow has a very characteristic shape. This will help the doctor recognize if it is a dangerous species.

When it is unknown what insect caused the bite, the diagnosis becomes clinical, meaning the doctor will analyze the visible signs and the patient’s history. The doctor may ask about the onset of symptoms, whether there was recent exposure to places where spiders usually live, such as dark areas. They will also observe if the lesion shows characteristics compatible with bites from venomous species.

In these cases, a follow-up may be required to see if the symptoms progress while other possible causes of similar lesions are ruled out, such as skin infections or bites from other insects.

In any case, the doctor will evaluate the symptoms, the appearance of the bite, and the evolution of the affected area to determine the appropriate treatment.

Treatment for a Spider Bite

The appropriate treatment for a spider bite will be determined by the severity of the symptoms.

In most cases, it’s enough to clean the area with soap and water, apply cold compresses to reduce inflammation, and use conventional medications to relieve pain or itching.

If a blister or minor wound develops, it is important to keep it clean and dry to prevent secondary infections. Observation is important in the next 48 hours, as some reactions can worsen over time.

In cases where the spider bite is considered dangerous, medical treatment is essential, as symptoms can progress rapidly and affect different body systems.

The most feared species are the black widow, where treatment may include the administration of strong analgesics, muscle relaxants, and a specific antidote against its venom.

For the brown recluse, treatment includes careful management of the wound, medications to control pain, antibiotics in case of infection, and hospitalization may be required to monitor systemic complications. The treatment will also vary depending on whether the person is allergic to the spider’s venom or not.

In any case, early intervention significantly improves the patient’s outcome.

At the Internal Medicine department at ABC Medical Center, we can provide you with specialized care. Contact us!