Inclusion Criteria:  Written informed consent provided prior to conducting any study-specific assessment. Male and female adults, 18 through 65 years of age, inclusive. Current diagnosis of SAD as defined in the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition, and confirmed by the MINI. Clinician-rated LSAS total score ≥70 at Screening (Visit 1). Clinician-rated Hamilton Depression Score 17-items total score <18 at Screening (Visit 1). Women of childbearing-potential must be able to commit to the consistent and correct use of an effective method of birth control throughout the study, and must also have a negative urine pregnancy test result at both Screening (Visit 1) and Baseline (Visit 2), prior to investigational product (IP) administration. Effective methods of contraception include: condoms with spermicide, diaphragm with spermicide, hormonal contraceptive agents (oral, transdermal, or injectable), or implantable contraceptive devices. Negative COVID-19 test either in the presence of COVID-19 symptoms or after direct exposure to someone with a positive COVID-19 test  Exclusion Criteria:  Any history of bipolar disorder (I or II), schizophrenia, schizoaffective disorder, psychosis, anorexia or bulimia, premenstrual dysphoric disorder, autism-spectrum disorder, or obsessive-compulsive disorder.  Any other current Axis I disorder, other than SAD, which is the primary focus of treatment. Note that subjects with concurrent Generalized Anxiety Disorder are eligible for the study provided that Generalized Anxiety Disorder is not the primary diagnosis.  Subjects who meet criteria for moderate or severe alcohol or substance use disorder within the 1 year prior to Study entry.  In the opinion of the investigator, the subject has a significant risk for suicidal behavior during the course of their participation in the study, or  At Screening (Visit 1): the subject scores "yes" on items 4 or 5 in the Suicidal Ideation section of the Columbia-Suicide Severity Rating Scale (C SSRS) with reference to a 6-month period prior to screening; or At Screening (Visit 1): the subject has had 1 or more suicidal attempts with reference to a 2 year period prior to screening; or At Baseline (Visit 2): the subject scores "yes" on items 4 or 5 in the Suicidal Ideation section of the C-SSRS with reference to screening; or The subject is considered to be an imminent danger to themself or others. Clinically significant nasal pathology or history of significant nasal trauma, nasal surgery, total anosmia, or nasal septum perforation that may have damaged the nasal chemosensory epithelium. An acute or chronic condition, including an infectious illness, uncontrolled seasonal allergies at the time of the study, or significant nasal congestion that potentially could affect drug delivery to the nasal chemosensory epithelium. Two or more documented failed treatment trials with a registered medication approved for SAD, at any time during the lifetime of the subject, whereby an adequate treatment trial is defined as that described in the package insert for a particular drug during which the subject received an adequate medication dosage (defined as the treatment dose indicated in the package insert to obtain efficacy for that particular drug). Use of any psychotropic medication within 30 days before study entry (other than medication permitted for insomnia: eszopiclone, ramelteon, melatonin, zaleplon, zolpidem, or antihistamines). Use of any anxiolytics, such as benzodiazepines or unapproved treatments such as beta blockers, within 30 days before study entry; concomitant use is prohibited during the study. Subjects who have been taking benzodiazepines daily for 1 month or longer at the time of Visit 1 are not eligible to participate. Use of any over-the-counter product, prescription product, or herbal preparation for treatment of the symptoms of anxiety or social anxiety within 30 days before study entry; concomitant use is prohibited during the study. Prior participation in a clinical trial involving PH94B. Women who have a positive urine pregnancy test prior to IP administration. Subjects with clinically significant abnormalities in hematology, blood chemistry, urinalysis, electrocardiogram, or physical examination identified at the Screening visit or Baseline visit that in the clinical judgment of the Investigator, could place the subject at undue risk, interfere with study participation, or confound the results of the study.