One-liner#

Systematic evaluation of fatigue—the most common complaint in primary care—focusing on distinguishing treatable medical causes from lifestyle factors, sleep disorders, and psychiatric conditions while avoiding excessive testing in low-risk patients.

Quick nav#

• Red flags / send to ED
• Key history
• Focused exam
• Differential (quick pattern recognition)
• Workup
• Initial management
• Management by diagnosis
• Follow-up
• Patient instructions
• Smartphrase snippets

Red flags / send to ED#

• Chest pain or dyspnea at rest with fatigue → ED (ACS, PE, decompensated HF)
• Syncope or presyncope → ED if recent or recurrent
• Severe weakness (can’t get out of bed, can’t lift arms) → ED (myasthenia crisis, GBS, severe hypokalemia)
• Altered mental status → ED
• Active suicidal ideation → ED for psychiatric evaluation
• Signs of adrenal crisis (hypotension, severe nausea/vomiting, confusion) → ED

Urgent (expedited outpatient workup):

• Fatigue with unintentional weight loss >10%
• Fatigue with new lymphadenopathy or hepatosplenomegaly
• Fatigue with severe anemia (Hgb <7)
• Fatigue with fever >3 weeks
• Fatigue with progressive neurologic symptoms

Key history#

Characterize the fatigue:

• Duration (acute <1 month, subacute 1-6 months, chronic >6 months)
• Onset (sudden vs gradual)
• Constant vs intermittent
• Severity (functional impact—can they work? exercise? do ADLs?)
• What makes it better or worse?

Distinguish fatigue from related symptoms:

• Fatigue: Lack of energy, exhaustion, need to rest
• Sleepiness: Tendency to fall asleep (suggests sleep disorder)
• Weakness: Decreased muscle strength (suggests neuromuscular disease)
• Dyspnea on exertion: Shortness of breath limiting activity (suggests cardiopulmonary disease)

Sleep assessment (critical):

• Hours of sleep per night
• Sleep quality (restful vs unrefreshing)
• Snoring, witnessed apneas, gasping (OSA)
• Difficulty falling asleep or staying asleep (insomnia)
• Restless legs, leg movements
• Shift work, irregular schedule
• Screen time before bed

Psychiatric screening:

• Depression (PHQ-2/PHQ-9): Anhedonia, low mood, hopelessness
• Anxiety (GAD-2/GAD-7): Worry, tension, difficulty relaxing
• Stress: Work, family, financial, caregiving burden
• Substance use: Alcohol, cannabis, other drugs

Lifestyle factors:

• Exercise (too little OR overtraining)
• Diet quality, meal patterns
• Caffeine intake and timing
• Hydration
• Work hours, job demands
• Caregiving responsibilities

Medical history review:

• Chronic diseases (diabetes, HF, COPD, CKD, liver disease, cancer)
• Autoimmune conditions
• Recent infections (post-viral fatigue)
• Thyroid disease
• Anemia history
• Sleep apnea

Medication review (common culprits):

• Beta-blockers
• Antihistamines (especially first-generation)
• Benzodiazepines, sleep aids
• Opioids
• Antidepressants (especially sedating ones)
• Antiepileptics (gabapentin, pregabalin, topiramate)
• Muscle relaxants
• Antihypertensives (clonidine, methyldopa)
• Statins (myalgia/fatigue)

Review of systems (targeted):

• Weight changes
• Fever, night sweats
• Dyspnea, orthopnea, edema (HF)
• Polyuria, polydipsia (diabetes)
• Cold intolerance, constipation, dry skin (hypothyroidism)
• Heat intolerance, palpitations, weight loss (hyperthyroidism)
• Joint pain, rashes (autoimmune)
• Headaches, vision changes
• GI symptoms (malabsorption, IBD)
• Menstrual history (heavy periods → anemia)

Focused exam#

Vital signs:

• Blood pressure (hypotension → adrenal insufficiency, dehydration)
• Heart rate (bradycardia → hypothyroidism; tachycardia → anemia, hyperthyroidism, anxiety)
• Weight, BMI (obesity → OSA; weight loss → malignancy, hyperthyroidism)
• Temperature

General appearance:

• Affect, mood (flat affect, psychomotor retardation → depression)
• Pallor (anemia)
• Cushingoid features
• Signs of chronic illness

HEENT:

• Conjunctival pallor (anemia)
• Thyroid (goiter, nodules)
• Oropharynx (Mallampati score if OSA suspected)
• Dry mucous membranes

Neck:

• Lymphadenopathy
• JVD (heart failure)

Cardiovascular:

• Murmurs
• S3 (HF)
• Peripheral edema

Pulmonary:

• Breath sounds
• Signs of effusion or consolidation

Abdomen:

• Hepatosplenomegaly
• Masses
• Ascites

Skin:

• Pallor
• Jaundice
• Dry skin, coarse hair (hypothyroidism)
• Hyperpigmentation (adrenal insufficiency)
• Rashes (autoimmune)

Neurologic:

• Strength testing (true weakness vs fatigue)
• Reflexes (delayed relaxation → hypothyroidism)
• Gait

Psychiatric:

• Mood, affect
• Concentration
• Psychomotor changes

Differential (quick pattern recognition)#

Common/likely (outpatient)#

Can’t-miss / urgent#

Workup#

Approach: Targeted testing based on history and exam, not shotgun labs.

Initial workup (most patients with fatigue >1 month):

Second-tier testing (based on clinical suspicion):

STOP-BANG Questionnaire (≥3 = high risk for OSA):

• Snoring loudly
• Tired/sleepy during day
• Observed apneas
• Pressure (HTN)
• BMI >35
• Age >50
• Neck circumference >40 cm (16 in)
• Gender male

When NOT to order extensive workup:

• Fatigue <4 weeks with clear precipitant (viral illness, stress, sleep deprivation)
• Fatigue with obvious lifestyle factors (insufficient sleep, no exercise, high stress)
• Fatigue with clear psychiatric diagnosis (depression, anxiety) not yet treated
• Young, healthy patient with normal exam and no red flags

Approach if initial workup negative:

1. Reassess for depression, anxiety, sleep disorders
2. Detailed sleep history; consider sleep study
3. Review medications again
4. Address lifestyle factors (sleep, exercise, stress)
5. Consider chronic fatigue syndrome if criteria met (>6 months, not explained by other conditions)
6. Close follow-up; avoid repeated testing without new findings

Initial management#

General approach:

1. Thorough history to identify likely cause(s)
2. Targeted workup based on clinical suspicion
3. Address modifiable factors (sleep, exercise, stress, medications)
4. Treat identified cause
5. If no cause found, supportive management and follow-up

Universal recommendations (while investigating):

• Sleep hygiene optimization
• Regular physical activity (even if fatigued—start low, go slow)
• Balanced diet; adequate hydration
• Limit alcohol
• Stress management
• Review and minimize sedating medications if possible

Management by diagnosis#

Depression-related fatigue#

Education:

• Fatigue is a core symptom of depression
• Treatment improves energy, but may take 2-4 weeks
• Exercise helps even when you don’t feel like it

Treatment:

Follow-up: 2-4 weeks to assess response; adjust as needed.

Obstructive sleep apnea#

Education:

• OSA causes unrefreshing sleep and daytime fatigue
• Treatment dramatically improves energy and reduces cardiovascular risk
• Weight loss helps but CPAP is primary treatment

Treatment:

• CPAP (continuous positive airway pressure) — first-line
• Weight loss (if overweight/obese)
• Positional therapy (if positional OSA)
• Oral appliance (if mild OSA or CPAP intolerant)
• Avoid alcohol and sedatives before bed

Referral: Sleep medicine for CPAP initiation and titration.

Follow-up: 4-6 weeks after CPAP initiation to assess compliance and symptom improvement.

Hypothyroidism#

Education:

• Low thyroid causes fatigue, weight gain, cold intolerance
• Treatment with thyroid hormone replacement is very effective
• Takes 4-6 weeks to feel full effect

Treatment:

Follow-up: TSH in 6-8 weeks; adjust dose to normalize TSH.

Iron deficiency anemia#

Education:

• Low iron causes fatigue, weakness, shortness of breath
• Need to find the cause (blood loss, poor intake, malabsorption)
• Iron replacement takes 2-3 months to fully replete stores
• Ferritin <30 ng/mL indicates iron deficiency even with normal hemoglobin—treat if symptomatic

Treatment:

Workup for cause:

• Premenopausal women: Often menstrual blood loss; assess flow
• Postmenopausal women and men: GI source until proven otherwise → colonoscopy, consider EGD

Follow-up: CBC and ferritin in 4-8 weeks; continue iron 3-6 months after Hgb normalizes to replete stores.

Vitamin B12 deficiency#

Education:

• B12 deficiency causes fatigue, neurologic symptoms, anemia
• Common in elderly, vegans, and metformin users
• Neurologic damage may be irreversible if untreated

Treatment:

Follow-up: B12 level in 2-3 months; lifelong supplementation if pernicious anemia or ongoing cause.

Vitamin D deficiency#

Education:

• Vitamin D deficiency is very common and can contribute to fatigue
• Also important for bone health and immune function
• Supplementation is safe and inexpensive

Treatment:

Follow-up: Recheck level in 8-12 weeks if repleting; maintain level >30 ng/mL.

Chronic fatigue syndrome (CFS/ME)#

Recognition criteria:

• Fatigue >6 months
• Substantially reduced activity level
• Post-exertional malaise (worsening after physical/mental exertion)
• Unrefreshing sleep
• Plus cognitive impairment OR orthostatic intolerance
• Not explained by other medical or psychiatric conditions

Education:

• CFS is a real, disabling condition
• No cure, but symptoms can be managed
• Pacing is key—avoid boom-bust cycles

Management:

• Activity pacing (stay within “energy envelope”)
• Sleep hygiene optimization
• Treat comorbid conditions (depression, pain, sleep disorders)
• Graded exercise therapy (controversial; must be patient-led and gentle)
• Cognitive behavioral therapy (for coping, not cure)
• Avoid unproven treatments

What NOT to do:

• Don’t dismiss the patient
• Don’t push aggressive exercise (can worsen symptoms)
• Don’t order repeated extensive workups

Referral: Consider referral to CFS specialty clinic if available.

Follow-up: Regular follow-up for support and symptom management; 4-8 weeks initially.

Medication-induced fatigue#

Common culprits:

• Beta-blockers (especially non-selective)
• Antihistamines (diphenhydramine, hydroxyzine)
• Benzodiazepines and Z-drugs
• Gabapentin, pregabalin
• Opioids
• Muscle relaxants
• Clonidine
• Some antidepressants (TCAs, mirtazapine, trazodone)

Management:

• Review necessity of each medication
• Consider alternatives with less fatigue
• Reduce dose if possible
• Time sedating medications to bedtime
• Deprescribe if appropriate

Follow-up: 2-4 weeks after medication change to reassess.

Lifestyle-related fatigue#

Education:

• Sleep, exercise, diet, and stress all affect energy
• Small changes can make a big difference
• Improvement takes time—be patient

Management:

• Sleep: 7-9 hours; consistent schedule; dark, cool room; no screens 1 hour before bed
• Exercise: 150 min/week moderate activity; start with 10-minute walks if deconditioned
• Diet: Regular meals; balanced nutrition; limit processed foods; adequate protein
• Hydration: 8 glasses water daily
• Stress: Identify stressors; relaxation techniques; consider counseling
• Caffeine: Limit to morning; avoid after 2 PM
• Alcohol: Limit to 1-2 drinks; avoid near bedtime

Follow-up: 4-6 weeks to reassess after implementing changes.

Follow-up#

Initial follow-up:

• 2-4 weeks if starting treatment for identified cause
• 4-6 weeks if implementing lifestyle changes
• Sooner if symptoms worsen or new symptoms develop

What to reassess:

• Symptom improvement (use consistent scale: “How’s your energy on 1-10?”)
• Sleep quality
• Mood
• Functional status
• Medication adherence and side effects
• Lab results if pending

Return precautions:

• Worsening fatigue despite treatment
• New symptoms (weight loss, fever, night sweats, weakness)
• Chest pain, severe dyspnea
• Thoughts of self-harm
• Inability to perform daily activities

Patient instructions#

• Fatigue is very common and usually has a treatable cause. We’re going to work together to figure out what’s causing yours.
• Good sleep is essential. Aim for 7-9 hours per night, keep a consistent schedule, and avoid screens before bed.
• Exercise actually helps fatigue, even when you don’t feel like it. Start with short walks and gradually increase.
• Eat regular, balanced meals. Skipping meals or eating poorly can worsen fatigue.
• Limit caffeine to the morning and alcohol to 1-2 drinks (or none).
• Stress and mood affect energy levels. Let us know if you’re feeling down or overwhelmed.
• Take any prescribed medications as directed. Some take a few weeks to work.
• Call us if your fatigue is getting worse, you’re losing weight without trying, you have fevers or night sweats, or you’re having thoughts of harming yourself.

Smartphrase snippets#

.FATIGUEEVAL Evaluation for fatigue. Duration [X weeks/months]. Patient describes [constant/intermittent] fatigue with [functional impact]. Sleep: [hours/night, quality, snoring/apneas]. Mood: PHQ-2 [score]. Stressors: [present/absent]. Medications reviewed: [sedating meds or none]. ROS: [pertinent positives/negatives]. Exam: Vitals normal. [Findings or normal exam]. Initial workup: CBC, CMP, TSH, UA. [Additional tests if indicated]. Plan: [Address modifiable factors; await labs; treat identified cause]. Follow-up in [2-4 weeks].

.FATIGUENORMAL Fatigue evaluation with normal initial workup. CBC, CMP, TSH, UA within normal limits. No red flags on history or exam. Most likely etiology: [sleep insufficiency/stress/depression/deconditioning/medication effect]. Plan: [Sleep hygiene counseling / exercise prescription / mood treatment / medication adjustment]. Patient advised that lifestyle factors are the most common cause of fatigue and improvement takes time. Follow-up in [4-6 weeks] to reassess. Return sooner if worsening or new symptoms.

.FATIGUEOSA Fatigue with high suspicion for obstructive sleep apnea. STOP-BANG score [X]. Patient reports [snoring, witnessed apneas, daytime sleepiness, morning headaches]. BMI [X], neck circumference [X]. Referring for polysomnography. Counseled on sleep hygiene, weight loss, avoiding alcohol before bed. Will follow up after sleep study to discuss results and treatment options.

.FATIGUEDEPRESSION Fatigue in setting of depression. PHQ-9 score [X]. Patient endorses [low mood, anhedonia, sleep changes, etc.]. No suicidal ideation. Medical workup [normal / pending]. Starting [antidepressant] for depression, which should also improve energy over 2-4 weeks. Discussed importance of sleep, exercise, and social connection. Follow-up in 2-4 weeks to assess response. Return precautions reviewed including worsening mood or thoughts of self-harm.

Related pages#

• Iron Deficiency Anemia (problem) — comprehensive management of iron deficiency
• Depression — fatigue as core symptom
• Hypothyroid — common endocrine cause
• Hypothyroidism (problem) — comprehensive thyroid management
• Insomnia — sleep-related fatigue
• Anemia workup — if iron deficiency suspected
• Weight loss (unintentional) — if fatigue with weight loss
• Dyspnea (chronic) — if dyspnea on exertion vs fatigue

Coding/billing notes#

• R53.83: Other fatigue (most common code)
• R53.1: Weakness (if weakness is the primary complaint)
• R53.81: Chronic fatigue, unspecified
• G93.32: Myalgic encephalomyelitis/chronic fatigue syndrome
• F32.9: Major depressive disorder, single episode, unspecified
• E03.9: Hypothyroidism, unspecified
• D50.9: Iron deficiency anemia, unspecified
• G47.33: Obstructive sleep apnea
• E53.8: Vitamin B12 deficiency
• E55.9: Vitamin D deficiency