What will I notice after taking fish oil? A timeline of effects and benefits

October 7, 2025 •

4 min read

Research shows the brain is composed of about 60% fat, with omega-3s being critical components. This explains why the effects of supplementation, including what will I notice after taking fish oil, often begin with subtle changes in mood and cognitive function before developing into long-term systemic benefits.

Quick Summary

Initial fish oil intake may cause mild digestive issues, but consistent, long-term use can lead to improved mood, cognitive function, skin hydration, and joint comfort.

Key Points

Timeline Varies: What you notice after taking fish oil depends on whether you are in the initial weeks (mild side effects) or after several months (significant health benefits).
Initial Side Effects: Be aware of potential digestive issues like fishy burps, heartburn, or nausea during the first few weeks, which can often be managed by taking the supplement with food.
Visible Benefits (1-3 months): Improvements in mood, cognitive clarity, skin hydration, and reduced joint stiffness typically become noticeable after 4 to 12 weeks of consistent intake.
Significant Long-Term Changes: Deeper benefits like lowered triglycerides, enhanced skin health, and better management of chronic inflammation become more pronounced with continued use over 3-6+ months.
Factors for Success: To maximize results, ensure you take a high-quality supplement consistently, preferably with a fatty meal, and be patient for the long-term effects to build up.
Consider the 'Off' Effect: Many people realize the benefits only when they stop taking the supplement and previous symptoms, like aching joints, return.
Consult a Professional: Discuss fish oil supplementation with a doctor, especially if you take blood thinners or have other medical conditions, to avoid interactions and determine appropriate use.

Taking a fish oil supplement introduces essential omega-3 fatty acids, primarily EPA and DHA, into your system. These powerful compounds are gradually incorporated into your cell membranes, a process that determines when you begin to notice changes. Because this is a systemic and gradual process, a person's first observations often differ from the more significant, long-term benefits they may experience after several months.

Initial weeks: Adjusting and subtle changes

In the first couple of weeks, most people will not experience dramatic shifts in their health. Any initial effects are often related to your body adjusting to the new intake of fat. The most commonly reported experiences are mild and gastrointestinal.

Fishy aftertaste and burps: A very common side effect, often a sign that the supplement is digesting. Taking the capsules with a meal can help minimize this.
Mild stomach upset: Some may experience minor nausea, heartburn, or loose stools as their body adapts. Splitting your intake between meals can sometimes help.
Minor mood or clarity boosts: Some individuals, particularly children, may notice a slight improvement in focus or mood within a timeframe of 4–8 weeks.

1-3 months: The first noticeable benefits emerge

As the omega-3s build up in your body's tissues, more tangible benefits start to appear. This is typically when people first notice the positive effects they were expecting.

Enhanced skin health: Skin cells turn over approximately every 4–6 weeks, so it is within this timeframe that you might notice your skin appearing more hydrated, vibrant, and less irritated. Some studies show improved skin hydration after three months of consistent intake.
Reduced joint discomfort: For those taking fish oil for joint health, it may take 8–12 weeks to feel a difference. The anti-inflammatory effects gradually take hold as omega-3s integrate into the cell membranes.
Improved brain function: In adults, studies have noted improvements in cognitive performance, memory, and mood after consistent use. Effects on conditions like brain fog and anxiety can take a few weeks to become apparent.
Lowered triglyceride levels: For those monitoring their cardiovascular health, blood tests may show a reduction in triglyceride levels after 8–12 weeks of consistent, high-quality supplementation.

3-6+ months: Deeper, sustained changes

For the benefits of fish oil to reach their full potential and become sustained, long-term use is necessary. It takes time for omega-3 levels in red blood cells to plateau, often taking several months.

Sustained mood stabilization: For mental wellness, consistent, long-term use is what provides lasting stability and reduced symptoms of depression and anxiety.
Significant inflammation reduction: Deeper, chronic inflammation is reduced over this period, benefiting conditions like rheumatoid arthritis.
Deeper skin improvements: You may notice enhanced skin texture and reduced symptoms of conditions like eczema, as omega-3s continue to support the skin's barrier function.
Cardiovascular protection: Long-term, consistent omega-3 intake is linked to a reduced risk of heart disease, heart attacks, and improved blood pressure control.

Potential side effects and long-term benefits compared

Consistency is key to moving beyond the initial adjustment phase to experience the supplement's full advantages. The table below compares potential initial irritations with the more significant, enduring health benefits.


Initial Potential Side Effects (Days/Weeks)	Sustained Long-Term Benefits (Months)
Fishy aftertaste	Improved cognitive function
Mild indigestion/burping	Reduced joint pain & stiffness
Minor nausea	Enhanced skin hydration & texture
Headache	Lowered triglyceride levels
Temporary loose stools	Stabilized mood and anxiety reduction

What influences how quickly you see results?

Several factors impact how long it takes for a person to notice the effects of fish oil:

Product potency: The concentration of the active ingredients (EPA and DHA) varies significantly between products, so always check the label. A healthcare provider can help determine appropriate intake levels.
Diet and baseline levels: Individuals with a very low baseline intake of omega-3s may notice changes faster than those who already consume fatty fish regularly. A diet high in omega-6 fatty acids can also delay the anti-inflammatory effects.
Consistency: Taking the supplement regularly is critical for building up omega-3 levels in the body.
Taking with a fatty meal: Absorption of omega-3 is significantly enhanced when consumed with a meal containing some fat.

How to track your progress

Since many of the benefits of fish oil are gradual and systemic, it can be helpful to find ways to track your progress. Some changes, like improvements in joint pain, may become apparent when you realize you are able to perform certain activities more comfortably. Other benefits are best measured objectively.

Blood tests: Regular blood work can monitor key markers like triglyceride levels, especially for those with cardiovascular health concerns.
Omega-3 Index Test: For those who want a precise measure, an Omega-3 Index test can provide a powerful snapshot of your omega-3 status. It measures EPA and DHA levels in your red blood cells, reflecting your intake over the last few months.

Conclusion

In summary, what you will notice after taking fish oil depends on the timeframe and your body's individual response. Short-term effects are often subtle and focused on initial digestive adjustment, while meaningful improvements in cognitive function, joint comfort, and skin health typically appear after 1–3 months of consistent use. For deeper, sustained benefits, a commitment to long-term supplementation is required. While omega-3s offer significant potential benefits, they are best viewed as part of a broader healthy lifestyle that includes a balanced diet and regular exercise. For the highest safety and effectiveness, always consult a healthcare provider before beginning any new supplement, particularly if you have pre-existing conditions or are on other medications. More information on the effects and considerations of fish oil can be found on the Mayo Clinic's website.

Frequently Asked Questions

Initial, subtle benefits related to mood, brain fog, or skin hydration may appear within 4-8 weeks. More significant improvements for joint health, triglycerides, and chronic inflammation usually take 8-12 weeks or longer with consistent use.

You can take fish oil at any time, but it's best to take it with a meal containing some fat. This significantly increases absorption and can reduce the likelihood of side effects like fishy burps or heartburn.

Yes, omega-3 fatty acids, especially DHA, are crucial for brain function. Many report improved memory, focus, and mental clarity, often noticing a reduction in brain fog within 4-12 weeks of consistent supplementation.

Common and generally mild side effects include fishy aftertaste, bad breath, heartburn, nausea, and loose stools. Taking supplements with meals or freezing them can help. A healthcare provider can discuss potential risks, including those associated with higher intake levels.

Some studies suggest that fish oil can contribute to stronger hair, reduce hair loss, and increase hair density due to its ability to nourish hair follicles and reduce scalp inflammation. Visible results may take several months.

A higher concentration of EPA and DHA can potentially lead to noticeable results faster. However, the optimal amount depends on individual needs, and it's essential to discuss appropriate levels with a healthcare provider.

Be patient, as many benefits are gradual and take months to become significant. Ensure you are taking a high-quality supplement consistently with meals. Some people only realize the benefits once they stop taking it and old symptoms return. You can also get an Omega-3 Index test to check your levels objectively.