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Effect of intranasal oxytocin versus placebo on stress and repetitive behaviors in adults with autism

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What is this trial about?

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

The study focuses on individuals diagnosed with Autism Spectrum Disorder, a condition that affects communication, social interaction, and behavior. Participants will receive a nasal spray containing the hormone oxytocin or a placebo spray that looks the same but does not contain the active ingredient. The spray is given intranasal, meaning it is administered through the nose.

The main aim is to see whether daily use of the oxytocin spray for six weeks can reduce the level of stress that participants feel about themselves, as measured by a questionnaire called the PSS-10. Participants will be randomly assigned to one of the two spray groups and will use the spray each day for the study period.

During the study, participants will complete the stress questionnaire at the start, after the six‑week treatment period, and at several follow‑up visits to track any lasting changes. The study will last several weeks, with regular check‑ins to collect questionnaire responses and monitor safety.

The research process

The trial runs in 5 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Randomization and receipt of medication

    After joining the study, you will be randomly assigned to receive either oxytocin nasal spray or a placebo nasal spray that contains only saline solution.

    The study medication will be provided to you in a bottle labeled for intranasal use.

  2. Step 2

    First administration of nasal spray

    On the first day, you will use the nasal spray as instructed by the study team.

    Each dose contains 24 IU (international units) of the active substance and is applied once daily through the nose.

  3. Step 3

    Daily nasal spray for six weeks

    You will continue to administer the nasal spray every day for a total of six weeks.

    The spray is used intranasally, meaning it is placed inside the nose according to the provided instructions.

    If you are in the placebo group, the spray contains only saline and does not contain any active medication.

  4. Step 4

    Primary outcome assessment at week 7 (T1)

    One week after completing the six‑week treatment period (approximately seven weeks after randomization), you will complete the Perceived Stress Scale (PSS‑10) questionnaire.

    This questionnaire measures your level of self‑perceived stress and is used to compare your results with the baseline measurement taken before the treatment started.

  5. Step 5

    Follow‑up assessments (T2, T3, T4)

    After the primary assessment, you will be asked to complete the same stress questionnaire at three additional follow‑up sessions referred to as T2, T3, and T4.

    These follow‑up visits are scheduled at later time points determined by the study protocol to monitor any lasting effects of the treatment.

Who can join the trial?

5 criteria

  • Voluntary written informed consent – you must sign a form agreeing to join the study before any screening procedures begin.
  • You must be at least 18 years old when you sign the consent form.
  • A confirmed diagnosis of Autism Spectrum Disorder (ASD) – this means a doctor or a team of specialists has identified you as having autism using the standard guidelines called DSM‑5 (or the older guidelines DSM‑IV for specific types such as Autistic Disorder, Asperger Syndrome, or Pervasive Developmental Disorder‑Not Otherwise Specified).
  • The diagnosis must be made by a multidisciplinary team – a group of professionals from different fields (for example, doctors, psychologists, and therapists) who work together to evaluate you.
  • You must self‑report that you have been experiencing increased stress for at least the past month – you simply tell the study staff that you feel more stressed, without needing a formal questionnaire.

Who cannot join the trial?

9 criteria

  • Taking anti‑epileptic medication (drugs for seizures) or having a serious, not well‑controlled health problem such as severe anemia (very low red blood cells), low platelets, uncontrolled thyroid disease, uncontrolled diabetes, irregular heart rhythm (e.g., atrial fibrillation), fast heart rhythm, heart failure, high blood pressure, moderate‑to‑severe lung disease (COPD or severe asthma), moderate‑to‑severe kidney disease or dialysis, severe liver disease (cirrhosis or hepatitis), major stomach or intestinal surgery, poor nutrient absorption, or active cancer.
  • Having a severe intellectual disability (major limits in thinking and learning) because it makes it hard to give consent, follow study steps, use the nasal spray, or fill out questionnaires; people with a mild disability may join only if they are not under legal guardianship and can read at a fourth‑grade level.
  • Having a known syndrome that affects the reproductive hormonal system, such as Prader‑Willi syndrome or Angelman syndrome.
  • Having used chronic oxytocin treatment at any time during the past ten years.
  • Being allergic (having a hypersensitivity) to the active ingredient or any part of the nasal spray, including a latex allergy.
  • Using any of the following medicines while taking the nasal spray: prostaglandins (drugs that affect inflammation), inhalation anesthetics (gases used for anesthesia), systemic vasoconstrictors or sympathomimetic agents (drugs that narrow blood vessels or stimulate the nervous system), or receiving caudal anesthesia (spinal anesthesia given in the lower back).
  • Currently taking part in another interventional clinical trial that uses an investigational drug or device.
  • Being pregnant, breast‑feeding, or planning to become pregnant during the study; people who could become pregnant must not be pregnant at the start, must not breast‑feed, and must use effective birth control or abstain from vaginal intercourse for the whole study period.
  • Using high‑dose or long‑term external sex hormones that substantially change natural hormone levels, such as gender‑affirming hormonal therapy or other high‑dose hormone treatments; regular oral contraceptives are allowed.
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Investigated drugs

Oxytocin nasal spray is a medication that is sprayed into the nose. In this study participants used it every day for six weeks. Oxytocin is a hormone that the body naturally makes, and it is thought to help people feel calmer and more socially comfortable. The trial tested whether giving oxytocin through the nose could lower the participants’ own feeling of stress and reduce repetitive actions that are common in autism. The nasal spray was the active treatment being compared with a placebo spray.

What is already known about the treatment

  • Placebo - physiological water-based nasal sprays (NaCl 0.9%)

    This product is a sterile saline solution (0.9% NaCl) delivered as a nasal spray for intranasal use. It is widely used in clinical research as an inert control and does not act as a medication. It has no therapeutic indication and works only by delivering a small amount of water and salt, producing no pharmacologic effect. It is classified as an isotonic saline solution used as a placebo.

  • Oxytocin CD Pharma 6,7 mikrogram/dos nässpray, lösning

    Oxytocin is given as a nasal spray solution, with each spray delivering 24 IU for intranasal use. The drug is approved for obstetric purposes but is being studied experimentally for autism spectrum disorder, where it may help lower stress and repetitive behaviors. It works by binding to oxytocin receptors in the brain, influencing social and emotional pathways at the molecular level. Oxytocin belongs to the peptide hormone/neuropeptide class.

Investigated diseases

Autism spectrum disorder - Autism spectrum disorder is a neurodevelopmental condition that appears in early childhood and affects how a person perceives and interacts with the world. It is characterized by challenges in social communication, repetitive behaviors, and restricted interests. Symptoms often become more noticeable as social demands increase, such as when children start school. Over time, some individuals may develop coping strategies that reduce the impact of certain features, while others may experience increasing difficulties in adapting to new situations. The pattern of strengths and challenges can vary widely from person to person throughout life.
Trial detailsLast updated 5 Nov 2026
Age18+ yearsPhasePhase IIITrial ID2025-524797-42-00Protocol code2025-524797-42Estimated enrolment210 patientsSponsorUZ Leuven

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