Self-harm takes many physical forms and is accompanied by behavioral changes that are often more visible than the injuries themselves. Cutting is the method most people picture, but scratching, burning, hitting, and other forms are common, and most people who self-harm use more than one method over time. Recognizing the signs means looking beyond marks on the arms and paying attention to shifts in clothing choices, mood, social habits, and language.
Physical Signs Go Well Beyond Cuts on the Arms
When people think of self-harm, they tend to think of cuts on the forearms. That image is not wrong, but it is incomplete. Common forms of self-injury include cutting, severe scratching, burning, and banging or hitting the body against surfaces, and most people who self-harm have used more than one of these methods.1PubMed. Self-injury: a research review for the practitioner Because the popular image is so focused on cutting, other physical signs get overlooked.
Burns or branding marks, for instance, can appear as small circular scars from cigarettes or lighters, or as unusual-looking reddened patches. Bruises from hitting or banging may show up on the head, legs, or torso and be dismissed as clumsiness. Severe scratching can leave raw, raised lines that look different from accidental scrapes, particularly when they appear in parallel rows or in a repeated pattern on the same area. Biting that breaks or bruises the skin, pulling out hair, and interfering with wound healing (picking at scabs or reopening old cuts) are also forms of self-harm that leave physical evidence.
The marks themselves vary in age and appearance. Fresh wounds, healing scabs, and old scars appearing on the same body area at once suggest an ongoing pattern rather than a single incident. Unexplained wounds that appear repeatedly and do not match the person’s explanation deserve attention.
Where the Injuries Appear
The upper arms are the single most common location. In a study of adolescents who engaged in self-cutting, about two-thirds reported cutting only their upper arms, while roughly a third also cut other parts of the body.2PubMed. Adolescent self-cutting elsewhere than on the arms reveals more serious psychiatric symptoms That finding matters for two reasons. First, arms are the area most likely to be concealed by long sleeves, so a sudden switch to long-sleeved clothing in warm weather is a commonly cited warning sign. Second, injuries appearing beyond the arms, on the legs, stomach, chest, or elsewhere, may indicate more severe distress.
Research on gender and body location adds more detail. Females are more likely to injure their abdomen and legs, while males are more likely to injure their torso and chest.3PubMed Central. Characterizing gender differences in nonsuicidal self-injury: Evidence from a large clinical sample of adolescents and adults Males are also more likely to injure the face or genitals.4PubMed. Nonsuicidal self-injury and gender: patterns of prevalence, methods, and locations among adolescents These less expected locations are easier to miss in a casual check, and they reinforce why a careful, full-body examination matters when a young person has unexplained wounds.
Behavioral and Emotional Warning Signs
The physical marks are sometimes hidden, so behavioral changes are frequently the first clue that something is wrong. These signs do not confirm self-harm on their own, but several appearing together deserve a closer conversation.
- Social withdrawal: Pulling away from friends, family, and activities they once enjoyed. Research on people in crisis identifies social withdrawal as one of the most common behavioral warning signs alongside low mood and frequent crying.5Frontiers in Public Health. Suicide warning signs of self-identification in patients with mood disorders: a qualitative analysis based on safety planning
- Concealment behaviors: Wearing long sleeves or pants in hot weather, refusing to change clothes for sports, covering arms with wristbands or jewelry, or becoming defensive when asked about visible marks.
- Keeping sharp objects: Unexplained possession of razors, box cutters, or similar items, particularly if kept hidden in a bedroom or personal bag.
- Frequent unexplained injuries: Repeated cuts, burns, or bruises accompanied by vague or inconsistent explanations like “the cat scratched me” or “I fell.”
- Emotional instability: Rapid mood shifts, intense reactions to interpersonal conflict, and difficulty calming down. Clinical research highlights that self-harm, emotional instability, and relational difficulties tend to cluster together and can change rapidly in severity.6Personalized Psychiatry. Self-harm, emotional instability, and relational difficulties in adolescents in psychological crisis: change over time as a tool for clinical risk assessment
- Avoiding situations that expose skin: Skipping pool parties, refusing medical check-ups, or becoming anxious about gym class or swimming.
None of these signs in isolation means someone is self-harming. A teenager who suddenly wants to wear long sleeves might just be cold, or following a fashion trend. But a cluster of these behaviors, especially when combined with emotional distress or a known stressful event, warrants gentle inquiry rather than dismissal.
How Methods and Patterns Differ by Gender
Self-harm affects all genders, but the specific methods, locations, and internal experiences differ in ways that matter for recognition. Females tend to report higher overall rates of self-injury and are more likely to cut and scratch. Males are more likely to burn, brand, or hit themselves.4PubMed. Nonsuicidal self-injury and gender: patterns of prevalence, methods, and locations among adolescents Because burning and hitting leave different-looking marks than cutting does, self-harm in boys and men is easier to misinterpret as the result of accidents or fights.
There are also internal differences worth knowing about. In a large clinical sample, males reported lower levels of urges to self-harm and endorsed fewer emotion-regulation reasons for the behavior, while females were more likely to report self-harm on the abdomen and legs across a wider number of body locations.3PubMed Central. Characterizing gender differences in nonsuicidal self-injury: Evidence from a large clinical sample of adolescents and adults The practical takeaway is that looking for stereotypical cuts on the forearms will catch some cases while missing others, especially in boys, who may present with burns on the chest or bruises from hitting that get attributed to rough play or sports.
Age Changes What Self-Harm Looks Like
Self-harm does not look the same at age thirteen as it does at age twenty-three. Among adolescents, cutting and burning are the most commonly reported methods. Through late adolescence, the proportion of people self-harming drops substantially, and by young adulthood the decline continues more slowly, with no single form of self-harm predominating.7The Lancet. The natural history of self-harm from adolescence to young adulthood: a population-based cohort study
The gender balance also shifts with age. Among 12-to-14-year-olds presenting to emergency departments for self-harm, females outnumber males by more than six to one. By ages 22 to 25, the ratio narrows to roughly even. Younger adolescents are more likely to self-poison (typically with over-the-counter medications), while older young adults are more likely to use prescribed medications, alcohol, or recreational drugs in their self-harm. Repetition of self-harm is most common in the youngest group, though multiple repeated episodes concentrate in the oldest age bracket.8Journal of Affective Disorders. Age-related differences in self-harm presentations and subsequent management of adolescents and young adults at the emergency department
Rates have also been climbing. A ten-year national registry study found that self-harm rates rose by about a fifth over the study period, with the steepest increases among girls aged 10 to 14. Peak rates appeared among 15-to-19-year-old females and 20-to-24-year-old males.9PubMed. Increasing rates of self-harm among children, adolescents and young adults: a 10-year national registry study 2007-2016 The practical point for parents and teachers is that self-harm is not rare, and the age at which it starts may be younger than they expect.
Why People Self-Harm, and Why That Matters for Spotting It
Understanding the motivation behind self-harm is not just academic. It helps explain why the behavior is so often hidden and what emotional patterns to watch for. A large body of evidence consistently points to affect regulation as the primary driver: intense negative emotion builds up, and self-injury provides temporary relief.10PubMed. The functions of deliberate self-injury: a review of the evidence People describe escalating distress before an episode and a sharp drop in that distress immediately afterward.
Beyond emotion regulation, self-punishment is a strongly supported function. People who self-harm frequently describe feeling they deserve the pain. Other reasons include using pain to break through emotional numbness or dissociation, distracting from psychological distress, and making internal suffering feel physically visible and real.11PubMed Central. Non-Suicidal Self-Injury and Emotional Dysregulation in Male and Female Young Adults: A Qualitative Study A smaller number of people describe interpersonal reasons: wanting others to understand how much they are hurting, or seeking care and support they feel unable to ask for directly.
This means the behavioral signs that tend to precede self-harm episodes mirror these functions. Watch for patterns of intense self-criticism, statements about deserving bad things, expressions of feeling “numb” or “empty,” and difficulty putting emotions into words. These are not personality quirks; they are the emotional landscape in which self-harm becomes a coping tool.
Digital and Online Signals
For younger people especially, online behavior can be a window into self-harm that the physical body keeps hidden. Research consistently finds that young people who self-harm are more active on social networks than peers who do not. They use these platforms to communicate about their distress, seek support from other users, and sometimes share images or descriptions of self-injury.12PubMed Central. The role of online social networking on deliberate self-harm and suicidality in adolescents: A systematized review of literature
A systematic review of social media content related to self-harm found that common themes in posts included discussing triggers or motivations, talking about concealment strategies, and expressing thoughts about suicide.13PLOS ONE. A Systematic Review of Social Media Use to Discuss and View Deliberate Self-Harm Acts If you notice a young person engaging with self-harm content online, following accounts that post graphic imagery, or using coded language and hashtags associated with self-injury communities, those are signals worth paying attention to. The relationship between online activity and self-harm runs both ways: people seek out communities that reflect their experience, and exposure to self-harm content can reinforce the behavior.
Peer Influence Is Real
Self-harm does not spread the way a cold does, but social influence plays a documented role. A longitudinal study of adolescents found that among girls, a best friend’s frequency of self-harm at one time point predicted the girl’s own self-harm months later, even after accounting for her own prior history. The same effect was not found for boys.14PubMed Central. Peer Influence and Nonsuicidal Self Injury: Longitudinal Results in Community and Clinically-Referred Adolescent Samples
Experimental evidence adds another layer. When young adults were exposed to a story about a peer who self-harmed, their perceived ability to control their own urges to self-harm dropped significantly, and the effect was stronger when the peer was someone they admired.15Acta Neuropsychiatrica. The influence of peer non-suicidal self-harm on young adults’ urges to self-harm: experimental study Broader reviews of the literature support the idea that social modeling can increase the risk of someone starting to self-harm, particularly among people who already have certain psychological vulnerabilities.16PubMed. The impact of social contagion on non-suicidal self-injury: a review of the literature
For parents and educators, this means that when one young person in a friend group is known to self-harm, it makes sense to be more attentive to the others, not with suspicion but with awareness.
What Parents Actually Experience
One of the more poignant findings in this area comes from qualitative research with parents. Many parents suspected something was wrong before their child told them or before any professional got involved. They noticed changes in clothing, mood, or behavior but struggled to act on those observations. Communication difficulties and a tendency to underestimate the seriousness of what they were seeing led to delays in addressing the behavior.17The British Journal of Psychiatry. Parents’ perspectives on adolescent self-harm: Qualitative study
Parents described not knowing how to bring the subject up, fearing they would make it worse, or hoping it was a phase that would pass on its own. This hesitation is understandable but costly. Self-harm screening tools used in clinical settings often uncover episodes that are not recorded anywhere in clinical notes. In one pilot of a self-harm questionnaire for adolescents, a fifth of young people disclosed self-harm on the questionnaire that was not recorded anywhere in their clinical records.18PubMed. Brief report: the Self Harm Questionnaire: a new tool designed to improve identification of self harm in adolescents The gap between what is happening and what is documented is wide, and parental observation can help close it.
When It Might Not Be Self-Harm
Not every unexplained mark or repetitive behavior is self-injury. Body-focused repetitive behaviors like skin picking, hair pulling, and nail biting can leave visible damage that looks concerning but serves a different psychological purpose. Research comparing these behaviors to non-suicidal self-injury finds meaningful differences. People who engage in self-injury are more likely to do so to regulate intense negative emotions, relieve feelings of emptiness, or influence how others respond to them. People with body-focused repetitive behaviors, by contrast, tend to perform them more automatically, often without conscious awareness, to reduce boredom, or to “fix” perceived appearance flaws.19PubMed. Body-focused repetitive behaviors and non-suicidal self-injury: A comparison of clinical characteristics and symptom features
The distinction matters because the approaches to helping are different. A person who picks at their skin absentmindedly while watching television needs different support than someone who deliberately cuts to relieve emotional anguish. If you are unsure whether marks on someone’s body reflect intentional self-harm or a repetitive habit, the emotional context surrounding the behavior is the most reliable guide. Self-injury tends to co-occur with higher levels of stress, anxiety, and depression, while body-focused repetitive behaviors, though distressing, are more habitual in nature.
Language and Communication Patterns
There is growing interest in whether the way someone writes or speaks can flag self-harm risk. Recent research analyzing digital language found that people who self-harm tend to use first-person singular pronouns (“I,” “me,” “my”) at higher-than-average rates, along with more words expressing sadness and anger.20npj Mental Health Research. Psychosocial dynamics of suicidality and nonsuicidal self-injury: a digital linguistic perspective The elevated use of “I-words” is thought to reflect a kind of inward-turning attention, a preoccupation with the self and one’s suffering that shows up in everyday writing.
This is not a diagnostic tool you can use at the dinner table, but it is worth noting as part of a broader pattern. If someone’s text messages, social media posts, or journal entries increasingly center on themselves in a negative emotional frame, with frequent references to sadness, anger, or self-blame, that shift in tone deserves attention alongside any physical or behavioral changes you have observed.
Coexisting Health Problems
Self-harm rarely appears in isolation. Among people with frequent self-harm episodes, the rates of co-occurring conditions are strikingly high. One study found that roughly three-quarters of individuals with frequent self-harm reported chronic pain, and over a third met criteria for major depressive disorder, both rates far above what is typical in the general population.21Frontiers in Psychiatry. Physical and mental illness comorbidity among individuals with frequent self-harm episodes: A mixed-methods study Substance use disorders, borderline personality features, and histories of sexual assault were also common and frequently overlapped with one another.
For anyone trying to spot self-harm in someone they care about, this means the signs may be tangled up with other health problems. Someone managing chronic pain may have injuries that are partly self-inflicted and partly related to their pain condition. Someone with depression may be withdrawing socially for reasons that include but are not limited to self-harm. The comorbidity is the rule rather than the exception, and it argues for asking direct questions rather than trying to assign a single explanation to a set of concerning behaviors.
Self-Harm in Supervised Settings
Self-harm does not stop when someone enters a hospital or residential care facility. In fact, the way it presents can change. On psychiatric inpatient units, where supervision is higher and access to typical means like razors is restricted, young people adapt. They may use different objects, injure themselves in different ways, or find less obvious methods that are harder for staff to detect.22Journal of Affective Disorders Reports. Characteristics of self-harm on an adolescent psychiatric inpatient unit based on neurodevelopmental diagnoses This adaptability underscores that self-harm is driven by a psychological need, not merely by the availability of a particular tool. Removing the tool without addressing the need shifts the form of the behavior rather than stopping it.
Emergency department clinicians also face the challenge of identifying who is at highest risk for repeating self-harm or dying by suicide after discharge. One clinical screening tool identifies four risk factors that, taken together, flag patients who should receive more intensive assessment: recent self-harm in the past year, living alone or being homeless, cutting as the method of harm, and current treatment for a psychiatric disorder. In the validation data, the combination caught the vast majority of patients who went on to die by suicide within six months.23Psychological Medicine. The development of a population-level clinical screening tool for self-harm repetition and suicide: the ReACT Self-Harm Rule These are not just clinical details; they are things that friends and family can be aware of too. Someone who has harmed themselves recently, lives alone, uses cutting, and is already in psychiatric treatment is statistically at higher risk, and the people around them should know that.