Intimacy and oxytocin are associated with slightly faster healing of skin wounds

Researchers from the University Hospital of Zurich and the University of Zurich report that intimate physical contact combined with intranasal oxytocin was associated with slightly faster healing of skin wounds and decreased levels of stress hormones in healthy romantic couples.

Social connections and physical health

Close romantic partnerships have often been associated with better physical health and lower mortality, with relationship quality often serving as a more powerful predictor of outcomes than relationship status alone. Repeated supportive, affectionate, and intimate interactions within couples have been proposed as a pathway by which immune function and longevity might improve.

Physical contact represents a central channel of social support during times of stress, and experimental studies have associated affectionate touch with reduced autonomic activation, lower cortisol, and less subjective stress.

Couples interventions that cultivate relationship quality, particularly cognitive-behavioral approaches, have improved both relationship functioning and health outcomes in targeted clinical populations such as people with cancer, chronic illnesses, or mental health problems, while preventive interventions aimed at the general population remain less frequently studied.

Oxytocin has been considered a neuropeptide mediator of the positive effects of social interactions on physical and psychological well-being. Animal and human experiments have linked affectionate touch to increases in endogenous oxytocin and have shown that exogenous oxytocin can improve sensitivity to touch and blunt stress responses.

In the study “Intranasal Oxytocin and Physical Intimacy for Dermatological Wound Healing and Neuroendocrine Stress,” published in JAMA PsychiatryResearchers conducted a double-blind, randomized, placebo-controlled clinical trial to examine the relationship between repeated administration of oxytocin, a brief couple interaction exercise, and natural physical intimacy on wound healing and stress responses.

Couples were recruited for a pre-registered clinical trial at the University Hospital of Zurich, Switzerland. Participants included 80 healthy heterosexual couples, for a total of 160 participants with an average age of 27.6 years and an average relationship duration of almost four years, most of whom were employed and college educated.

love hurts

Couples attended three laboratory visits over one week. During the first visit, researchers collected questionnaires and urine samples and created four standardized suction wounds on each participant’s forearms using a vacuum and heat protocol that separated the dermo-epidermal junction.

The tops of two blisters were removed at the first visit and two more at the 24-hour visit, with all wounds covered by hydrocolloid bandages.

Dosage of oxytocin and placebo

Approximately 50 minutes after injury, each partner self-administered a nasal spray containing either intranasal oxytocin or a placebo. Oxytocin spray delivered three puffs per nostril for a total dose of 24 IU in the laboratory, and sprays for home use at a daily dose of 32 IU administered as two puffs per nostril twice daily for five days. The placebo sprays were identical in composition, apart from the absence of oxytocin.

Approximately 45 minutes after spraying, couples were randomly assigned to a structured interaction, the Partner Appreciation Task (PAT), or an unstructured interaction condition (nPAT).

PAT included a 10-minute videotaped conversation in which partners used a list of 23 positive relationship characteristics, such as trust, joint planning, and dyadic coping, to guide mutual positive feedback, gratitude, and attention to valued aspects of the relationship. In the control condition, couples talked freely for 10 minutes while being filmed.

Wound severity was assessed using a revised Photographic Wound Assessment Tool (revPWAT). Two independent evaluators evaluated each wound for granulation tissue type, amount of granulation tissue, wound margins, and skin variability such as erythema, encrustation, or pigmentation. Each dimension was given a score of 0 to 4, with total wound severity ranging from 0 to 16. Assessments took place one hour, 24 hours, and seven days after injury.

Monitoring intimacy and the biology of stress

The researchers supplemented the laboratory protocol with a five-day assessment using an iDialogPad handheld device. Across six prompts per day, participants indicated whether they had interacted with their partner since the previous entry and categorized these interactions as conversation, affectionate touch, sexual activity, conflict, or other categories.

Each prompt also captured momentary emotional state, including a rating on a 5-point scale from very stressed to very relaxed, as well as recent eating, drinking, and exercise activity.

Participants also collected saliva samples to measure cortisol upon waking, 30 minutes later, 2.5 hours, 8 hours, 12 hours, and at bedtime. The samples were frozen for later analysis.

Oxytocin Results

Wound severity scores decreased over time, indicating healing over the seven-day period. The effects of oxytocin alone and PAT alone on revPWAT scores were not significant, nor were the interactions between these factors significant.

A three-way interaction between time, oxytocin, and PAT emerged, suggesting that oxytocin was associated with better wound healing for couples tasked with performing the partner appreciation task, but not for those in an unstructured interaction condition.

Sensitivity checks that removed two influential cases weakened the PAT-related effect of oxytocin, which then no longer reached statistical significance thresholds.

Intimacy Results

Analyzes then focused on physical intimacy measured in daily life through ecological momentary assessment. Models predicting healing between 24 hours and seven days after injury, adjusted for initial wound severity, tested affectionate touch and sexual activity separately. In both cases, oxytocin alone and intimacy measures alone showed no significant main effects on wound severity.

For affectionate touch, a three-way interaction between time, oxytocin, and touch indicated that more frequent daily affectionate touch in the oxytocin group predicted greater improvement in wound healing, whereas affectionate touch in the placebo group showed no such association. Sensitivity analysis retained this effect at a similar magnitude with a statistically significant result.

For sexual activity, a parallel three-way interaction showed that higher levels of daily sexual activity in the oxytocin group were associated with better wound healing, with no corresponding trend in the placebo group.

After removing influential cases, this interaction is below significance levels.

Intimacy, cortisol and perceived stress

Models probing the link between perceived stress and intimacy revealed that oxytocin administration did not significantly change the likelihood of affectionate contact or sexual activity when examined over the ecological momentary assessment period.

Ratings of relaxation predicted affectionate touch and sexual activity, suggesting that participants tended to engage in physical intimacy at times when they already felt more relaxed.

Cortisol analyzes showed no main effect of oxytocin administration on overall daily cortisol secretion. Cortisol decreased over study days and the number of affectionate touch episodes showed no significant relationship with cortisol. In contrast, more frequent sexual activity throughout the day was associated with lower daily cortisol levels, independent of oxytocin affect and other covariates.

Points to remember about oxytocin

The investigators concluded that intranasal oxytocin did not function as a simple autonomous stimulator of wound healing or stress regulation. Oxytocin showed no consistent effects on healing, intimacy, or cortisol.

Associations with better wound outcomes only emerged when oxytocin coincided with a structured positive interaction with natural affectionate touch and sexual activity.

The authors present oxytocin as a social amplifier, playing a role in modulating the impact of intimate interactions rather than as a direct therapeutic agent in itself. The observed links between intimacy, oxytocin, cortisol, and wound healing could provide the basis for future work on interventions that jointly address relational processes and neurohormonal modulation in health and recovery contexts.

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