What is the biggest health risk associated with eggs? The low-down on Salmonella

October 8, 2025 •

4 min read

According to the Centers for Disease Control and Prevention, an estimated one in every 20,000 raw eggs is contaminated with Salmonella bacteria. This harmful bacterium is the single biggest health risk associated with eggs, potentially causing severe foodborne illness if proper handling and cooking procedures are not followed.

Quick Summary

This article explores the risks of Salmonella contamination in eggs, covering how bacteria enter eggs, who is most vulnerable, and the symptoms of infection. It provides crucial steps for safe purchasing, storing, and cooking to reduce risks and discusses the benefits of pasteurized eggs.

Key Points

Salmonella Contamination: The biggest health risk associated with eggs is contamination with Salmonella bacteria, which can cause severe food poisoning.
Internal and External Risk: Salmonella can be present inside an egg before the shell is even formed (vertical transmission) or can penetrate the porous shell from the environment after laying (horizontal transmission).
Vulnerable Populations: Infants, young children, older adults, pregnant women, and individuals with weakened immune systems are at the highest risk for severe illness from Salmonella.
Safe Handling is Key: Proper refrigeration, avoiding cracked eggs, and thorough cooking until the yolks and whites are firm are essential steps to prevent infection.
Pasteurization as a Safeguard: For dishes with raw or lightly cooked eggs, using pasteurized egg products is the safest option as they have been heat-treated to kill bacteria.
Cholesterol Re-evaluated: Unlike outdated concerns, modern nutritional science views dietary cholesterol from eggs as less of a risk factor for heart disease for most healthy people than other saturated fats in the diet.

Understanding Salmonella: The Primary Risk with Eggs

For many, eggs are a staple in a healthy, balanced diet. They are a powerhouse of protein, vitamins, and minerals. However, despite their nutritional benefits, a significant health risk looms, primarily from the bacteria Salmonella. While heart disease and cholesterol were once major concerns, current scientific consensus and evidence-based dietary guidelines have shifted, emphasizing food safety and bacterial contamination as the most pressing health risk associated with eggs.

Salmonella can be present both on the exterior of an eggshell and, more critically, inside the egg itself. This internal contamination can occur in a laying hen’s reproductive tract before the shell even forms, making external washing ineffective. The danger lies in consuming raw or undercooked eggs, as the heat from thorough cooking is what kills the bacteria. The illness caused by Salmonella, known as salmonellosis, can range from mild discomfort to severe, life-threatening complications, particularly for vulnerable populations.

The Mechanisms of Contamination

Egg contamination with Salmonella can happen in two primary ways: vertical and horizontal transmission.

Vertical Transmission: Internal Contamination

Vertical transmission occurs when the egg is contaminated from within the hen's reproductive system. A hen infected with Salmonella can lay eggs that already contain the bacteria. This is especially true for the Salmonella Enteritidis serotype, which is adept at colonizing the reproductive organs of poultry. When this happens, the bacteria are sealed inside the egg, impervious to external cleaning and washing methods.

Horizontal Transmission: External Contamination

Horizontal transmission happens when bacteria enter the egg from the external environment after it has been laid. Salmonella can be present in the hen's feces and can penetrate the porous eggshell, especially if the egg is laid in a dirty nesting area or stored improperly. Cracks in the shell provide an easy entry point for bacteria. This is why purchasing clean, uncracked eggs is a critical first step in reducing risk.

Who is at Highest Risk?

While anyone can contract salmonellosis, certain individuals are at a much higher risk for developing severe illness that may require hospitalization.

Infants and Young Children: Their immune systems are still developing, making them more susceptible to severe infection.
Older Adults (65+): Their immune systems may be weaker, increasing the risk of serious complications.
Pregnant Women: The illness can pose a risk to both the mother and the fetus.
Immunocompromised Individuals: People with weakened immune systems due to conditions like HIV/AIDS, cancer, or diabetes are at a significantly higher risk.

Comparison of Egg Risks: Salmonella vs. Cholesterol


Feature	Salmonella Risk	Dietary Cholesterol Concern
Primary Danger	Acute, severe foodborne illness (salmonellosis) from bacterial infection.	Long-term risk of heart disease, once linked directly to egg consumption.
Cause	Bacterial contamination of the egg, either internally or externally, especially in raw or undercooked forms.	High levels of dietary cholesterol in egg yolks.
Current Scientific View	A significant and immediate public health concern, particularly for vulnerable populations.	Not as influential as once thought. Research shows that saturated fat has a greater impact on blood cholesterol for most healthy people.
Prevention	Proper handling, refrigeration, and thorough cooking to kill bacteria. Use of pasteurized eggs for uncooked dishes.	Focus on overall dietary balance rather than limiting eggs. What you eat with your eggs matters more.
Severity	Can lead to severe diarrhea, vomiting, hospitalization, and, in rare cases, death.	A cumulative risk factor for cardiovascular disease over a long period, but less concerning for most healthy individuals.

Crucial Steps for Safe Egg Handling and Preparation

Given the risk, prioritizing safe handling and preparation is non-negotiable. The Food and Drug Administration (FDA) and USDA provide clear guidelines to minimize exposure to Salmonella.

Refrigerate Immediately: Always store eggs in their original carton in the main part of the refrigerator, not the door, where temperatures fluctuate. Keep the refrigerator at or below 40°F (4°C).
Inspect for Cracks: Never use eggs with cracked or dirty shells. Bacteria can enter easily through these tiny openings. If an egg cracks after purchase, break it into a clean container, refrigerate, and use within two days.
Cook Thoroughly: Cook eggs until both the yolk and white are firm. Dishes containing eggs, like casseroles or quiches, should reach an internal temperature of 160°F (71°C). For runny yolks, be aware that the risk of Salmonella is higher.
Use Pasteurized Eggs for Raw Dishes: For recipes that call for raw or lightly cooked eggs, such as homemade mayonnaise, hollandaise sauce, or Caesar salad dressing, use pasteurized eggs or egg products to ensure safety.
Practice Proper Hygiene: Wash hands, utensils, and surfaces thoroughly with hot, soapy water before and after handling raw eggs.

The Role of Pasteurization

Pasteurized eggs are subjected to a controlled heat treatment that kills harmful bacteria like Salmonella without cooking the egg. This process is particularly useful for foodservice operations and home cooks preparing recipes with raw or lightly cooked eggs. While still requiring careful handling, they offer an additional layer of safety for those most at risk.

Conclusion: A Balanced Perspective

Ultimately, the biggest health risk associated with eggs is bacterial contamination, primarily Salmonella, which can lead to serious foodborne illness. While past concerns over dietary cholesterol have been largely re-evaluated and minimized for healthy individuals, the danger of improperly handled eggs remains a relevant public health issue. By following established food safety practices—including safe purchasing, proper storage, and thorough cooking—the risk of Salmonella can be dramatically reduced, allowing most people to enjoy the nutritional benefits of eggs with peace of mind. For those in high-risk groups or preparing uncooked egg dishes, pasteurized egg products offer the safest option.

Visit FoodSafety.gov for more information on safe food handling practices.

Frequently Asked Questions

The biggest health risk associated with eggs is contamination with Salmonella bacteria, which can cause a serious foodborne illness known as salmonellosis if the eggs are not handled and cooked properly.

Salmonella can contaminate an egg in two main ways: either internally from an infected hen's reproductive organs before the shell is formed, or externally from feces that then penetrate the porous eggshell.

For most healthy people, the dietary cholesterol from eggs is not a major concern. Newer research has found that dietary saturated fats have a much greater impact on blood cholesterol levels than the cholesterol consumed from eggs.

The safest way to cook eggs is to heat them until both the yolk and white are firm. This thorough cooking process kills any potential Salmonella bacteria.

For recipes requiring raw or lightly cooked eggs, it is highly recommended to use pasteurized eggs or egg products. These have been heat-treated to eliminate harmful bacteria.

Pregnant women, older adults, young children, and immunocompromised individuals should be most careful about egg safety, as they are at a higher risk for severe illness from Salmonella.

No, washing eggs at home is not recommended. Eggshells are porous, and washing can remove a protective coating and push bacteria from the shell's surface into the egg.

Store eggs in their original carton in the main body of the refrigerator, not the door, where temperatures are more stable. Keep the refrigerator at or below 40°F (4°C).