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Study of paracetamol effects on emotions and thinking in healthy adults aged 18 to 30 years

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What is this trial about?

A plain-language summary of the goals, design and what participants do

This study is looking at healthy adults aged 18 to 30 years to explore possible effects of paracetamol on emotions and thinking. Paracetamol is a common pain reliever that is widely available and used to treat pain and fever. The study will compare paracetamol in tablet form to a placebo, which is also given as a tablet. The purpose of the study is to find out whether paracetamol can reduce negative emotional experiences compared to placebo over 7 days of treatment.

Participants will take either paracetamol or placebo tablets for 7 days. During this time, they will complete questionnaires to report their feelings, including negative and positive emotions, anxiety, depression, stress levels, and sleep quality. The study will also measure brain activity using a technique that records electrical signals from the brain while participants view emotional images and complete tasks designed to create stress. Blood samples will be taken to measure certain substances in the body that are related to inflammation.

The study is designed so that neither the participants nor the researchers know who is receiving paracetamol and who is receiving placebo during the treatment period. This approach helps ensure that the results are not influenced by expectations. The maximum daily dose of paracetamol will be 1000 milligrams, and the total amount over the 7-day period will not exceed 7000 milligrams. The study aims to better understand whether this commonly used medication might have effects beyond pain relief.

The research process

The trial runs in 7 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Treatment period begins

    Your participation in the study will last for 7 days.

    You will be randomly assigned to receive either paracetamol 500 mg tablets or placebo tablets. A placebo is an inactive substance that looks like the real medication but contains no active ingredient.

    The tablets are film-coated and should be taken orally (by mouth).

    Neither you nor the study staff will know which treatment you are receiving during the study. This is called a double-blind study design.

  2. Step 2

    Daily medication intake

    You will take your assigned tablets daily throughout the 7-day treatment period.

    The specific dosage schedule and frequency of administration will be provided to you at the start of the study.

  3. Step 3

    Daily mood assessments

    Throughout the 7-day period, you will complete questionnaires to assess your emotional state.

    You will use the PANAS (Positive and Negative Affect Schedule), which measures both negative and positive emotions you may be experiencing.

  4. Step 4

    Day 7 assessments

    On the 7th day of the study, you will complete several questionnaires to evaluate your psychological well-being.

    You will complete the BAI-II (Beck Anxiety Inventory) to assess anxiety levels.

    You will complete the BDI-II (Beck Depression Inventory) to assess depression symptoms.

    You will complete the PSS (Perceived Stress Scale) to measure your stress levels.

    You will complete the PSQI (Pittsburgh Sleep Quality Index) to evaluate your sleep quality.

  5. Step 5

    Brain activity measurements

    You will undergo EEG (electroencephalography) testing. This is a non-invasive procedure that records electrical activity in your brain using sensors placed on your scalp.

    During the EEG, you will participate in an Emotional Interrupt Task, where you will view emotional images while your brain responses are measured.

    A resting state EEG will also be recorded while you are at rest, to measure your brain activity patterns.

  6. Step 6

    Stress response testing

    You will participate in the Montreal Imaging Stress Task (MIST), which is designed to create mild stress in a controlled setting.

    Your emotional and physical responses to stress will be measured during this task.

  7. Step 7

    Blood sample collection

    Blood samples will be taken during the study period to measure specific substances in your blood.

    The samples will be analyzed for IL-6 and IL-8, which are markers of inflammation in the body.

    Changes in these markers will be compared between the beginning and end of the treatment period.

Who can join the trial?

7 criteria

  • You must be between 18 and 30 years old
  • You must be in good health based on what you report about yourself and results from blood tests, which are laboratory tests that check various aspects of your health through a blood sample
  • Your body weight must be between 45 and 120 kilograms
  • Your Body Mass Index must be between 18.5 and 30. Body Mass Index is a number calculated from your height and weight that shows if your weight is in a healthy range
  • If you are a woman, you must use contraceptives, which are methods to prevent pregnancy, according to local requirements for people taking part in medical studies
  • You must be able to understand the study information and sign a document called informed consent, which shows you agree to take part and understand what the study involves
  • You must be able to communicate well in Norwegian, as all study materials and forms are written in this language

Who cannot join the trial?

9 criteria

  • You cannot participate if you are younger than 18 years old or older than 30 years old
  • You cannot participate if you have any existing health problems or medical conditions, as this study is only for healthy adults
  • You cannot participate if you are currently taking paracetamol, which is a common pain and fever-reducing medicine, or any other regular medications
  • You cannot participate if you have liver disease, which means problems with the organ that helps clean your blood and process medicines
  • You cannot participate if you have kidney disease, which means problems with the organs that filter waste from your blood
  • You cannot participate if you have an allergy or bad reaction to paracetamol or similar medicines
  • You cannot participate if you are pregnant, trying to become pregnant, or breastfeeding, which means feeding a baby with breast milk
  • You cannot participate if you drink large amounts of alcohol regularly
  • You cannot participate if you are taking part in another research study at the same time
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Investigated drugs

  • Paracetamol

    is a commonly used pain reliever and fever reducer that you can buy over the counter at pharmacies. In this study, researchers want to see if it might also affect emotions and thinking. The medication comes in tablet form and will be compared to a placebo to understand if it has any effects on mood and mental processes in healthy adults.

  • Placebo

    is an inactive tablet that looks like the real medication but contains no active ingredients. It is used in research studies to help scientists understand if the effects seen are truly from the medication being tested or from other factors.

What is already known about the treatment

Paracetamol – Paracetamol is a widely used pain reliever and fever reducer that is available in tablet form and taken by mouth. It is one of the most common over-the-counter medications approved for treating mild to moderate pain and reducing fever in both adults and children. Paracetamol works by blocking certain chemical messengers in the brain that signal pain and affect the body's temperature control center, though its exact mechanism at the molecular level is not completely understood. This medication belongs to a class of drugs called analgesics (pain relievers) and antipyretics (fever reducers), and in this clinical trial, researchers are investigating whether it might also have effects on emotions and thinking processes in healthy young adults.

Investigated diseases

This clinical trial is studying healthy adults aged 18-30 years, not individuals with diseases. The study focuses on the effects of paracetamol on negative emotions, stress responses, and mood in healthy participants. No specific diseases are being investigated in this research.
Trial detailsLast updated 8 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2025-522753-19-02Estimated enrolment84 patientsSponsorOslo Metropolitan University

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