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Depression in Primary Care: PHQ-9 Screening, Starting an SSRI and the Follow-Up Schedule

By Ala Alrashaeideh, Founder, NPPace·11 min read·Updated 2026-11-02

The short answer

Screen every adult for depression (USPSTF 2023, grade B), usually with the PHQ-2 followed by the PHQ-9, and treat a PHQ-9 of 10 or higher as probable major depression that still needs a diagnostic interview, a suicide-risk assessment and a bipolar screen. For mild to moderate major depressive disorder, offer evidence-based psychotherapy or a second-generation antidepressant such as an SSRI, check in early for adverse effects and suicidality, judge response after 4 to 8 weeks at a therapeutic dose, and continue the drug at the same dose for at least 6 months after remission.

Depression in primary care follows a fixed pathway: screen every adult, confirm the diagnosis and the suicide risk, start psychotherapy or an antidepressant, and measure the response on a schedule. The USPSTF (2023, grade B) recommends depression screening for all adults, including pregnant and postpartum patients and older adults, and the PHQ-9 is the tool most exam vignettes use. For mild to moderate major depressive disorder, the 2022 VA/DoD guideline recommends either psychotherapy or pharmacotherapy as monotherapy based on patient preference, an SSRI is the usual primary care starting drug, and once remission is reached the drug continues at the same dose for at least 6 months.

Who to screen and with what

The 2023 USPSTF statement gives a grade B to depression screening in adults 18 and older, and specifically includes pregnant and postpartum persons and adults 65 and older. It found no evidence on the best interval: a practical approach is to screen anyone not previously screened and use judgment about rescreening patients with risk factors, with ongoing assessment through pregnancy and the postpartum period. For adolescents 12 to 18 the separate 2022 USPSTF statement also gives a grade B; for children 11 and younger the evidence is insufficient.

Named tools include the PHQ family (PHQ-2 and PHQ-9), the Geriatric Depression Scale for older adults and the Edinburgh Postnatal Depression Scale for pregnant and postpartum patients.

The same 2023 statement gives an I grade (insufficient evidence) to screening the general adult population for suicide risk. That does not mean ignoring suicide risk. Any patient who screens positive for depression, or who answers PHQ-9 item 9 with anything other than "not at all," needs a direct suicide-risk assessment at that visit.

The two-step PHQ approach

The PHQ-2 asks about depressed mood and anhedonia over the past 2 weeks, each scored 0 to 3. A score of 3 or higher is the usual positive screen and triggers the full PHQ-9. The PHQ-9 scores each of the nine DSM symptoms 0 to 3, for a total of 0 to 27.


PHQ-9 score	Severity	Action proposed by the PHQ-9 authors
0 to 4	None or minimal	No treatment for depression
5 to 9	Mild	Watchful waiting, repeat the PHQ-9 at follow-up
10 to 14	Moderate	Treatment plan: counseling, follow-up and/or pharmacotherapy
15 to 19	Moderately severe	Active treatment with pharmacotherapy and/or psychotherapy
20 to 27	Severe	Start pharmacotherapy now; expedited referral if severe impairment or poor response

A score of 10 or higher is the usual cut-off for probable major depression. The score is a screen and a severity measure, not a diagnosis.

Confirming the diagnosis

DSM-5 criteria for major depressive disorder

Five or more of the nine symptoms must be present for at least 2 weeks, nearly every day, and at least one must be depressed mood or loss of interest or pleasure. The other symptoms are a change in weight or appetite, insomnia or hypersomnia, psychomotor agitation or retardation, fatigue, worthlessness or excessive guilt, poor concentration, and recurrent thoughts of death or suicide. The symptoms must cause clinically significant distress or impairment, must not be explained by a substance or a medical condition, and there must never have been a manic or hypomanic episode.

Rule out what mimics or complicates depression

Bipolar disorder. Before any antidepressant, ask about past episodes of decreased need for sleep with high energy, pressured speech or risky behavior, and about family history of bipolar disorder. An antidepressant alone in bipolar depression can trigger mania. A positive history means referral and a different treatment path.
Medical causes. Hypothyroidism, anemia, vitamin deficiencies, sleep apnea and medication effects can present as depression. Basic labs are guided by the history; a TSH is the test exam questions most often expect.
Substances. Alcohol and other drug use cause and worsen depressive symptoms. Screen with a validated tool such as AUDIT-C.
Grief and adjustment. Normal bereavement and adjustment disorder do not meet the full criteria for the full duration, although major depression can coexist with grief.

Suicide risk assessment and the 988 Lifeline

A positive item 9 or any disclosure of suicidal thoughts calls for a structured assessment the same day. The Columbia-Suicide Severity Rating Scale (C-SSRS) screener is widely used in primary care. It asks about wish to be dead, active suicidal thoughts, method, intent, plan and recent suicidal behavior. A yes to intent, a plan with intent, or suicidal behavior in the past 3 months marks high risk on the screener's standard triage.


Finding	Risk level	Response
Passive wish to be dead, no method, intent or plan	Lower	Safety plan, lethal means counseling, 988 number, close follow-up
Active thoughts with a method but no intent or plan	Moderate	Same-day behavioral health evaluation, safety plan, means restriction
Intent, a plan with intent, or a recent attempt or preparatory behavior	High	Do not leave the patient alone; emergency or crisis evaluation

Lethal means counseling covers firearm storage away from the home and limited medication quantities. Every patient with depression and any suicidal thinking should leave with the 988 Suicide and Crisis Lifeline: call or text 988, or chat at 988lifeline.org, available 24 hours a day. Veterans can press 1 after dialing to reach the Veterans Crisis Line.

First-line treatment

Psychotherapy or medication

For uncomplicated mild to moderate major depression, the 2022 VA/DoD guideline recommends offering either evidence-based psychotherapy or pharmacotherapy as monotherapy, chosen with the patient. The 2019 APA (psychological association) guideline likewise treats psychotherapy, such as cognitive behavioral therapy or interpersonal therapy, and second-generation antidepressants as comparable initial options for adults. For severe depression (the VA/DoD guideline gives a PHQ-9 above 20 as an example), persistent depression lasting more than 2 years, and recurrent depression, the VA/DoD guideline suggests combining medication and psychotherapy.

Choosing the antidepressant

The 2022 VA/DoD guideline lists an SSRI, an SNRI, bupropion, mirtazapine, trazodone, vilazodone or vortioxetine as initial options without ranking them, and no head-to-head evidence makes one agent clearly superior. In primary care and on the exam, an SSRI is the default because of tolerability, safety in overdose and once-daily dosing. The choice is then fitted to the patient.


Drug	Usual labeled starting dose	Choose it when	Watch for
Sertraline	50 mg daily	Most adults, cardiac disease, pregnancy and lactation discussions	GI upset, loose stools early
Escitalopram	10 mg daily	Most adults, older adults, coexisting anxiety	Dose-related QT prolongation at higher doses
Citalopram	20 mg daily	Most adults	QT prolongation: maximum 40 mg, and 20 mg in adults over 60
Fluoxetine	20 mg daily	Adolescents (FDA-approved age 8 and older for MDD), poor adherence (long half-life)	Activation, insomnia, many CYP2D6 interactions
Paroxetine	20 mg daily	Rarely first choice	Anticholinergic (avoid in older adults per Beers), weight gain, worst discontinuation syndrome
Bupropion	Labeled starting doses vary by formulation	SSRI sexual dysfunction, smoking cessation	Lowers seizure threshold: avoid in seizure disorder, bulimia, anorexia
Mirtazapine	15 mg at bedtime	Insomnia and poor appetite, older adults with weight loss	Sedation, weight gain

Confirm doses and age approvals against current labeling before prescribing. Escitalopram is FDA-approved for MDD from age 12 and fluoxetine from age 8.

Safety counseling at the first prescription

Boxed warning. All antidepressants carry a boxed warning for increased suicidal thoughts and behavior in children, adolescents and young adults under 25. Monitor closely in the first months and after every dose change.
Timing. Sleep and energy often improve before mood. Full benefit takes weeks, so early stopping is a common cause of "failure."
Common adverse effects. Nausea, headache, sleep change, sexual dysfunction. Most early GI effects fade within the first weeks.
Serious adverse effects. Hyponatremia from SIADH (higher risk in older adults and with diuretics), bleeding risk with NSAIDs, aspirin or anticoagulants, and serotonin syndrome with other serotonergic drugs (tramadol, triptans in combination, linezolid, MAOIs).
Do not stop abruptly. Discontinuation symptoms (dizziness, irritability, flu-like symptoms, "electric" sensations) are most prominent with short half-life drugs such as paroxetine and venlafaxine.

Follow-up schedule and measurement-based care

The exam expects a schedule, not just a drug.

Early contact. Within the first few weeks after starting, by visit, phone or portal, to check adverse effects, adherence and suicidal thinking.
Repeat the PHQ-9 at every follow-up. The score, not the impression, drives decisions.
Judge the trial. An adequate trial is generally 4 to 8 weeks at a therapeutic dose (APA practice guideline). If there is little improvement by about 4 weeks at a therapeutic dose, adjust rather than wait indefinitely; if there is partial improvement, a dose increase is the usual first move.
Response and remission. Response is commonly defined as a PHQ-9 drop of 50 percent or more; remission as a PHQ-9 below 5. Remission, not response, is the goal.
Continuation. Once remission is reached, the 2022 VA/DoD guideline recommends continuing the antidepressant at the therapeutic dose for at least 6 months to reduce relapse. For patients at high relapse risk, it suggests offering a course of CBT as well.
Maintenance and stopping. Patients with multiple prior episodes or chronic courses may need longer maintenance. When stopping, taper gradually and keep follow-up open.


Situation at 4 to 8 weeks	Next step
Remission (PHQ-9 under 5)	Continue the same dose for at least 6 months, then consider a gradual taper
Partial response, tolerating the drug	Increase the dose toward the labeled range
No response at an adequate dose, or intolerable adverse effects	Switch to another antidepressant or to psychotherapy, or add psychotherapy
Inadequate response after several adequate trials	Augmentation (for example a second-generation antipsychotic) or advanced options such as esketamine, usually with psychiatry

The 2022 VA/DoD guideline lists switching antidepressants, switching to or adding psychotherapy, and augmentation with a second-generation antipsychotic as options for inadequate response, and adds ketamine or esketamine for patients who have not responded to at least 2 adequate pharmacologic trials.

Referral and emergency triggers

Refer to psychiatry or behavioral health, or send for emergency evaluation, when any of these appear:

Suicidal intent, a plan with intent, recent suicidal behavior or homicidal ideation: emergency evaluation.
Psychotic features (hallucinations, delusions) or catatonia.
A history or current signs of mania or hypomania.
Severe depression with inability to care for self, eat or drink.
No adequate response after two well-conducted medication trials.
Complex perinatal depression, or depression complicated by an active substance use disorder or eating disorder.
Children and adolescents with moderate to severe depression when the provider lacks the resources for close monitoring.

Patient and family education

Depression is a medical condition with effective treatment, and improvement usually comes gradually over weeks.
Take the medication every day, even on good days, and do not stop it without a plan.
Expect early adverse effects to settle; call for agitation, new or worse suicidal thoughts, rash, confusion or unusual bleeding.
Avoid alcohol, and check before adding over-the-counter products such as St. John's wort or dextromethorphan combinations.
Family members should know the warning signs: talk of death, giving away belongings, withdrawal, sudden calm after severe distress. Anyone can call or text 988.
Sleep, physical activity and social contact support recovery but do not replace treatment.

How the exam tests this

Treating the screen as the diagnosis. A PHQ-9 of 14 is a reason for a diagnostic interview, not an automatic prescription. Options that skip the bipolar question or the suicide assessment are traps.
Missing bipolar disorder. A vignette that mentions a past week of little sleep with high energy, or a parent with bipolar disorder, is pointing away from SSRI monotherapy.
Stopping at response. A patient who feels better after 8 weeks and wants to stop is the classic setup. The correct answer continues the dose for at least 6 months after remission.
Switching too early. A patient at week 2 with nausea and no mood change needs reassurance and time, not a new drug.
Ignoring item 9. Any positive item 9 makes suicide assessment the priority over drug choice.
Drug-specific details. Citalopram over 20 mg in a patient over 60, paroxetine in an older adult, bupropion in a patient with an eating disorder or seizure history, and hyponatremia in an older adult taking a thiazide and an SSRI are favorite distractor patterns.
The young adult warning. The boxed warning age is under 25, not under 18.

Practice question

A 34-year-old woman was diagnosed with major depressive disorder 10 weeks ago with a PHQ-9 of 16. She has no history of mania and no suicidal ideation. She started sertraline 50 mg daily, increased to 100 mg at week 4. Today her PHQ-9 is 4, she sleeps well and has returned to work. She tolerates the medication and asks whether she can stop it now that she feels like herself again. Which of the following is the most appropriate plan?

A. Taper sertraline over 2 weeks and stop, since remission has been achieved.
B. Continue sertraline 100 mg daily for at least 6 months, then reassess with her about a gradual taper.
C. Reduce sertraline to 50 mg daily as a maintenance dose.
D. Stop sertraline today and restart it if her PHQ-9 rises above 10.

Answer: B. A PHQ-9 below 5 indicates remission, and the 2022 VA/DoD guideline recommends continuing the antidepressant at the therapeutic dose that produced remission for at least 6 months to reduce relapse. Option A stops treatment during the period of highest relapse risk, only 6 weeks into remission. Option C lowers the dose that achieved remission, which increases relapse risk; the continuation phase uses the full effective dose. Option D both stops abruptly, which risks discontinuation symptoms, and waits for a relapse to act.

Key points

USPSTF 2023 gives a grade B to depression screening for all adults, including pregnant, postpartum and older adults; suicide-risk screening of the general population is an I statement.
PHQ-2 of 3 or higher leads to the PHQ-9; a PHQ-9 of 10 or higher suggests probable major depression and requires a diagnostic interview, a bipolar screen and a suicide assessment.
A positive PHQ-9 item 9 needs a same-day structured assessment such as the C-SSRS, a safety plan, lethal means counseling and the 988 Lifeline.
For mild to moderate MDD, psychotherapy or a second-generation antidepressant are both first-line; combine them for severe, persistent or recurrent depression.
An SSRI such as sertraline or escitalopram is the usual first drug; watch citalopram dose limits, paroxetine in older adults and hyponatremia.
Repeat the PHQ-9 at every visit, judge the trial at 4 to 8 weeks at a therapeutic dose, and aim for remission (PHQ-9 under 5).
After remission, continue the same dose for at least 6 months before a gradual taper.

Related NPPace guides

Frequently asked questions

Common follow-up questions on Mental Health in Primary Care.

What PHQ-9 score means the patient has major depression?

None by itself. A score of 10 or higher is the usual screening cut-off for probable major depression, but the diagnosis requires a clinical interview confirming DSM-5 criteria, ruling out bipolar disorder, substances and medical causes.

How soon after starting an SSRI should I see the patient?

Make early contact within the first few weeks to check adverse effects, adherence and suicidal thinking, which the boxed warning asks prescribers to watch closely in the first months and after dose changes. Repeat the PHQ-9 at each visit and judge response after 4 to 8 weeks at a therapeutic dose.

When can an antidepressant be stopped?

The 2022 VA/DoD guideline recommends continuing the antidepressant at the therapeutic dose for at least 6 months after remission to reduce relapse. Stopping should then be gradual, and patients with recurrent episodes may need longer maintenance.

What should I do if PHQ-9 item 9 is positive?

Assess suicide risk the same day with a structured tool such as the C-SSRS screener, ask about plan, intent, means and past attempts, and match the response to the risk level, from safety planning and lethal means counseling with the 988 Suicide and Crisis Lifeline number to emergency evaluation.

Sources and references

US Preventive Services Task Force. Screening for Depression and Suicide Risk in Adults: US Preventive Services Task Force Recommendation Statement. JAMA. 2023;329(23):2057-2067. https://doi.org/10.1001/jama.2023.9297
McQuaid JR, Buelt A, Capaldi V, et al. The Management of Major Depressive Disorder: Synopsis of the 2022 U.S. Department of Veterans Affairs and U.S. Department of Defense Clinical Practice Guideline. Annals of Internal Medicine. 2022;175(10):1440-1451. https://doi.org/10.7326/M22-1603
American Psychological Association. Clinical Practice Guideline for the Treatment of Depression Across Three Age Cohorts. 2019. https://www.apa.org/depression-guideline
American Psychiatric Association. Practice Guideline for the Treatment of Patients With Major Depressive Disorder, Third Edition. 2010. https://psychiatryonline.org/pb/assets/raw/sitewide/practice_guidelines/guidelines/mdd.pdf
Kroenke K, Spitzer RL, Williams JB. The PHQ-9: validity of a brief depression severity measure. Journal of General Internal Medicine. 2001;16(9):606-613. https://doi.org/10.1046/j.1525-1497.2001.016009606.x
Posner K, Brown GK, Stanley B, et al. The Columbia-Suicide Severity Rating Scale: initial validity and internal consistency findings. American Journal of Psychiatry. 2011;168(12):1266-1277. https://doi.org/10.1176/appi.ajp.2011.10111704
988 Suicide and Crisis Lifeline. 2026. https://988lifeline.org

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