Does Eating Olive Oil Have Side Effects? What You Need to Know

November 1, 2025 •

4 min read

According to the Dietary Guidelines for Americans, healthy fats should constitute part of your diet. However, this leads many to ask: does eating olive oil have side effects? For most people, moderate consumption is safe and beneficial, but excessive intake or specific sensitivities can lead to negative reactions.

Quick Summary

Although olive oil is celebrated for its health benefits, overconsumption may cause digestive problems, weight gain, and lower blood pressure. Quality and moderation are crucial to reap the benefits while minimizing potential risks.

Key Points

Moderation is key: Excessive olive oil intake is the main cause of potential side effects, with a few tablespoons a day generally considered safe.
Digestive issues are common with excess: Consuming large amounts can trigger diarrhea, bloating, or stomach cramps due to its natural laxative effect.
Beware of high calories: Olive oil is calorie-dense, and overindulgence can contribute to weight gain if not balanced within your total daily intake.
Watch for drug interactions: Those on blood pressure or diabetes medication should monitor their intake, as olive oil can lower both blood pressure and blood sugar.
Allergies are rare but possible: Though uncommon, allergic reactions to olive oil can occur, with symptoms including skin rashes or gastrointestinal upset.
Prioritize quality and proper use: Stick with high-quality, unrefined Extra Virgin Olive Oil (EVOO) for the most benefits, and avoid heating it to excessively high temperatures.

The Surprising Truth About 'Liquid Gold'

Olive oil has long been hailed as a cornerstone of the healthy Mediterranean diet, prized for its high content of monounsaturated fats and powerful antioxidants. However, like any food, consuming it in excess or without understanding its properties can lead to unintended side effects. For the vast majority, moderate daily use is perfectly safe, but for those who overdo it or have underlying health conditions, caution is advised.

Potential Side Effects of Overconsumption

Even a good thing can be harmful in excess. Because olive oil is a concentrated source of calories and fat, overconsumption is the primary cause of negative side effects.

Digestive Issues

Olive oil has natural laxative properties, which can be beneficial in moderation for relieving constipation. However, if you consume excessive amounts, especially on an empty stomach, you might experience the following digestive discomforts:

Diarrhea: This is one of the most common reactions to too much olive oil, as it can overwhelm the digestive system.
Stomach cramps and bloating: The high fat content can be difficult to process in large quantities, leading to pain and a feeling of fullness.
Nausea: Some individuals report a feeling of nausea when consuming excessive oil, particularly when taken straight.

Weight Gain Risk

While olive oil contains healthy fats, it is also highly calorie-dense. Just one tablespoon contains approximately 120 calories. If you drizzle it generously over every meal without reducing other calorie sources, the added energy can contribute to weight gain over time. A 2025 study found that while olive oil was associated with less weight gain than other fats like butter or margarine, consuming it in excess without accounting for its calories can still lead to weight accumulation.

Skin-Related Issues from Excess Intake

For those with acne-prone or oily skin, high consumption of olive oil, or its topical application, can potentially exacerbate issues. The oil's thick consistency can clog pores, trapping bacteria and dead skin cells.

Olive Oil and Specific Health Concerns

Beyond simple overconsumption, certain health factors can influence how your body reacts to olive oil.

Drug Interactions

Olive oil can have a significant impact on certain bodily functions, which can interfere with medications.

Blood pressure: Olive oil may lower blood pressure. For individuals already taking antihypertensive drugs, this combined effect could cause blood pressure to drop too low, leading to dizziness or lightheadedness.
Blood sugar: Olive oil has been shown to improve blood sugar control. This is beneficial for many but requires caution for those with diabetes on medication. Taking olive oil alongside diabetes drugs might cause blood sugar levels to drop dangerously low.

Allergic Reactions and Sensitivities

While a true olive oil food allergy is rare, it is not impossible. Symptoms can range from mild skin rashes to more severe respiratory issues. Those with an existing allergy to olive pollen should consult a doctor before increasing consumption, though cross-reactivity is not guaranteed. A key distinction is that an allergy is caused by proteins in the olive, and highly filtered oils contain fewer proteins. Symptoms of an olive oil allergy or intolerance can include:

Hives and skin rashes
Abdominal pain and bloating
Vomiting
Wheezing or respiratory issues

The Importance of Quality and Moderation

Not all olive oils are created equal, and the type you consume can influence potential side effects. Extra Virgin Olive Oil (EVOO) is minimally processed, retaining its beneficial antioxidants and polyphenols, but it also has a lower smoke point. Heating EVOO to excessive temperatures can destroy its healthy compounds and potentially produce harmful substances. Refined olive oils, in contrast, have been processed to withstand higher temperatures, but they lack many of the health-promoting compounds found in EVOO.

Comparison: Excessive vs. Moderate Olive Oil Intake


Aspect	Excessive Intake (e.g., several shots per day)	Moderate Intake (e.g., 2-4 tablespoons daily)
Caloric Impact	High risk of weight gain due to calorie density	Fits into a healthy daily caloric allowance
Digestive System	Can cause diarrhea, bloating, or cramping	May aid digestion and help with constipation
Cardiovascular System	May cause blood pressure to drop too low in medicated individuals	Promotes heart health by lowering LDL cholesterol
Weight Management	Can be counterproductive to weight loss efforts	Promotes satiety, which can aid in weight management
Absorption of Nutrients	May disrupt the absorption of other essential nutrients	Enhances the absorption of fat-soluble vitamins

Conclusion: Balance is Best

So, does eating olive oil have side effects? The answer is yes, but primarily when consumed in excess or by those with specific sensitivities. For most people, adding high-quality extra virgin olive oil to a balanced diet is a healthy choice, offering a wealth of benefits for heart and overall health. However, the key lies in moderation and mindful consumption. By being aware of potential risks like digestive upset, caloric intake, and medication interactions, you can enjoy this nutritious oil without adverse effects. Always consult a healthcare professional before making significant changes to your diet, especially if you have pre-existing health conditions.

For more detailed information on olive oil and its effects, you can visit a trusted resource like WebMD.

Frequently Asked Questions

While often touted as a health trend, drinking olive oil straight can lead to digestive side effects like diarrhea, nausea, and stomach upset, especially for those with sensitive stomachs or if done excessively.

Yes, if consumed in excess. Olive oil is calorie-dense, and adding large amounts to your diet without reducing other calories can lead to weight gain, regardless of whether the fat is 'healthy'.

Yes, but an olive oil allergy is rare. Symptoms can include skin reactions (hives, itching), respiratory problems (wheezing), and gastrointestinal issues (pain, vomiting). It is a protein-based allergy, so filtered oils have fewer allergenic proteins.

Excessive intake can cause digestive upset such as diarrhea and bloating. Over the long term, it could contribute to weight gain and may cause blood pressure or sugar levels to drop too low, especially for those on medication.

Heating Extra Virgin Olive Oil (EVOO) can reduce its antioxidant and phenolic content, and using refined olive oil at high temperatures is generally safer. Overheating any oil can potentially produce harmful compounds.

Olive oil may help lower blood sugar levels. If you have diabetes and are on medication, you should monitor your blood sugar carefully when incorporating it into your diet and consult with a doctor.

A daily intake of 1 to 4 tablespoons is generally considered moderate and safe for most adults, though this depends on your overall dietary needs and health goals.