What is the side effect of olive oil?

October 19, 2025 •

3 min read

While celebrated as a cornerstone of the healthy Mediterranean diet, excessive consumption of olive oil can lead to unwanted side effects. A single tablespoon contains approximately 120 calories, and overindulgence can trigger issues ranging from digestive discomfort to weight gain. Moderation and quality are key to avoiding the negative aspects of this otherwise healthy fat.

Quick Summary

Excessive olive oil intake can cause weight gain due to its high calorie density, alongside potential digestive problems like diarrhea, and may negatively impact blood sugar and pressure levels. Allergic reactions, though rare, can also occur from consumption or topical use, leading to skin irritation or respiratory symptoms. Moderation is crucial for mitigating these risks.

Key Points

Weight Gain: Olive oil is calorie-dense, and overconsumption can easily lead to a caloric surplus and unwanted weight gain.
Digestive Distress: Excessive intake can upset the stomach, potentially causing bloating, gas, or diarrhea, particularly for those with sensitive digestive systems.
Blood Pressure and Sugar Fluctuations: While beneficial in moderation, large amounts can lower blood pressure and blood sugar levels too much, which can be risky for individuals with certain health conditions.
Skin Problems: Topical application can clog pores, leading to acne, and may damage the skin barrier, worsening conditions like eczema for some people.
Allergic Reactions: Though rare, both consuming and applying olive oil can cause allergic reactions, ranging from skin rashes to respiratory issues.

Potential Internal Side Effects of Overconsuming Olive Oil

Despite its many known health benefits, consuming excessive quantities of olive oil can lead to several internal issues. These are primarily linked to its high fat and calorie content.

Weight Gain

As a calorie-dense food, olive oil can contribute to unwanted weight gain if not consumed in moderation. Each tablespoon contains around 120 calories, which can add up quickly when used liberally. While studies show that a moderate amount is beneficial for weight management, excessive intake can easily lead to a caloric surplus and subsequent weight gain.

Digestive Problems

For some individuals, particularly those with sensitive digestive systems, a high intake of olive oil can cause discomfort. These issues may include bloating, flatulence, and even diarrhea, as the body struggles to process the large amount of fat. While olive oil can act as a natural and mild laxative in small doses, overdoing it can overstimulate the digestive tract and lead to undesirable results.

Effects on Blood Sugar and Blood Pressure

In some cases, over-consumption of olive oil has been linked to a significant drop in blood sugar levels, which can be dangerous for individuals with diabetes or those prone to hypoglycemia. Similarly, its blood pressure-lowering effects, which are typically seen as a benefit, can be exacerbated by excess intake, potentially leading to levels that are too low and causing symptoms like dizziness or lightheadedness.

Skin-Related Side Effects of Topical Application

While often praised for its benefits to skin health, topical use of olive oil is not without risks, especially for those with certain skin types or conditions.

Acne Breakouts: Olive oil is comedogenic, meaning it can clog pores. When applied to the face or other areas, it can trap bacteria and dead skin cells, leading to acne breakouts, particularly for those with oily or acne-prone skin.
Skin Barrier Damage: Some older research and observations from health organizations indicate that topical application of olive oil, due to its high oleic acid content, may damage the skin's natural barrier, worsening conditions like eczema.
Contact Dermatitis: Allergic reactions to olive oil, though rare, can manifest as contact dermatitis, causing skin irritation with symptoms such as rashes, itching, swelling, and burning. A patch test is recommended before widespread use.

Other Potential Side Effects

Beyond digestive and skin issues, other potential side effects of olive oil exist, particularly for those with existing health conditions.

Allergic Reactions: Though extremely rare, an allergy to olive oil or olive pollen can trigger symptoms ranging from skin rashes and hives to more serious respiratory issues like wheezing or asthma.
Medication Interference: Olive oil may interact with certain medications, including those for blood pressure and diabetes, potentially causing blood pressure or sugar levels to drop too low. Consulting a doctor is crucial for those on these medications.

Quality Matters: Refined vs. Extra Virgin Olive Oil

The type and quality of olive oil can significantly influence its potential side effects and health impact. Here is a comparison of refined and extra virgin olive oil (EVOO).


Feature	Extra Virgin Olive Oil (EVOO)	Refined Olive Oil
Processing	Minimally processed; mechanically extracted without high heat.	Chemically processed; loses beneficial compounds during production.
Nutritional Content	Retains high levels of polyphenols and antioxidants.	Lower in beneficial nutrients due to processing.
Health Benefits	Higher antioxidant content associated with stronger health benefits.	Fewer health benefits compared to EVOO.
Flavor	Robust and distinct flavor profile.	Milder, more neutral flavor.
Smoke Point	Moderate (190-210°C), suitable for most cooking.	Higher, making it suitable for high-heat applications.
Weight Impact	Associated with less weight gain due to its satiety effects.	Increased consumption linked to greater weight gain.

Conclusion

While olive oil is a highly nutritious fat with well-documented benefits, awareness of its potential side effects is important for balanced consumption. The key to mitigating risks like weight gain, digestive discomfort, or skin irritation lies in moderation and choosing high-quality extra virgin olive oil. Paying attention to how your body responds and consulting a healthcare professional for underlying health concerns is always recommended. By prioritizing moderation, you can enjoy the many health-promoting properties of olive oil without the unwanted side effects. For further details on the Mediterranean diet's approach to healthy fat intake, see this resource on the Mediterranean diet from the National Institutes of Health.

Frequently Asked Questions

Yes, consuming too much olive oil can lead to weight gain because it is very calorie-dense, containing about 120 calories per tablespoon. While its healthy fats are beneficial in moderation, a high daily intake can cause a caloric surplus.

For some individuals, especially with sensitive digestive systems, high consumption of olive oil can lead to digestive issues such as bloating, flatulence, and diarrhea. The high fat content can sometimes be difficult for the body to process in large quantities.

Olive oil can lower blood pressure, which is beneficial in moderate amounts. However, excessive consumption, especially in combination with blood pressure medications, can cause it to drop too low, leading to dizziness or other complications.

Yes, although it is very rare, an allergy to olive oil is possible. Symptoms can include skin irritation, rashes, or respiratory issues like wheezing. A more common olive-related allergy is to the pollen from olive trees.

Topical application can have side effects. Because olive oil is comedogenic, it can clog pores and cause acne breakouts. For individuals with dry or sensitive skin, it may also damage the skin's protective barrier and worsen conditions like eczema.

Extra virgin olive oil (EVOO) is generally considered better for health because it is minimally processed and retains a higher concentration of beneficial compounds like polyphenols and antioxidants. Refined olive oil has fewer of these nutrients.

Most dietary guidelines recommend a moderate intake, with some suggesting 1 to 2 tablespoons per day. This amount allows you to reap its health benefits without excessive calorie intake. Individuals on specific diets or with health conditions should consult a doctor.