1. Men and women age 18-75;

2. Diagnosis of current trichotillomania based on DSM-5 criteria and confirmed using the clinician-administered MIDI (13);

3. Hair pulling daily with urges to pull as the trigger in >50% of the episodes of pulling;

4. Women of childbearing age are required to have a negative result on a beta-human chorionic gonadotropin pregnancy test;

5. Women of childbearing potential utilizing a medically accepted form of contraception defined as double barrier, oral contraceptive, injectable contraceptive, implantable contraceptive devices, and abstinence

1. Infrequent pulling (i.e. less than daily) or automatic pulling (i.e. no urges to pull);

2. Unstable medical illness or clinically significant abnormalities on laboratory tests, EKG, or physical examination at screen as determined by the investigator;

3. History of seizures;

4. Myocardial infarction within 6 months;

5. Current pregnancy or lactation, or inadequate contraception in women of childbearing potential;

6. A need for medication other than semaglutide with possible psychotropic effects or unfavorable interactions as determined by the investigator;

7. Clinically significant suicidality (defined by the Columbia Suicide-Severity Rating Scale);

8. Lifetime history of bipolar disorder type I or II, schizophrenia, or any psychotic disorder;

9. Current skin picking disorder;

10. Initiation of psychotherapy or behavior therapy within 3 months prior to study baseline;

11. Initiation of psychotropic medications within 3 months prior to study baseline (stable doses will be allowed);

12. Previous treatment with semaglutide;

13. Use of any weight loss medications;

14. Body mass index (BMI, calculated as weight in kilograms divided by height in meters squared) less than 23;

15. Past-year substance use disorder other than tobacco use disorder or mild cannabis use disorder;

16. Recent (30-day) use of illicit drugs except cannabis;

17. History of diabetes, and current medical or neurological illness precluding participation based on physician judgment;

18. Personal or family history of medullary thyroid cancer or multiple endocrine neoplasia 2A or 2B;

19. History of pancreatitis.