Loss of appetite - red flag symptoms

Red flag symptoms in patients with loss of appetite and the importance of taking a detailed history.

Red flag symptoms

  • Significant unintentional weight loss
  • New-onset dyspepsia, age >55
  • Dysphagia
  • Symptoms raising suspicion of malignancy
  • Persistent low mood
  • Features suggesting alcohol dependence
  • Mini–Mental State Examination (MMSE) score, or equivalent, suggesting cognitive impairment
  • Genitourinary, gastrointestinal or respiratory symptoms
  • Loss of taste or smell contributing to the loss of appetite

Loss of appetite may only emerge when you ask about other presenting symptoms. It has a broad differential diagnosis, so a focused history is crucial.


It is important to understand what the patient means by ‘loss of appetite’. Try to determine what a normal appetite is for them, and over what time period their appetite has decreased. Loss of appetite may not have been noticed by the patient, but by friends or family.

Establish why the patient thinks they have lost their appetite and whether anything has changed in their life that may have led to this. Find out why the patient presented now.

Important features in the history include:

  • when the loss of appetite began
  • what the patient is eating on a daily basis
  • whether there are associated physical symptoms that stop the patient eating (for example dysphagia, odynophagia, epigastric pain or reflux).

Possible causes of loss of appetite

  • Acute or chronic bacterial or viral infections, including COVID-19
  • Metabolic problems, such as hypothyroidism
  • Malignancy1
  • Gastrointestinal conditions, such as gastritis, duodenitis or oesophagitis
  • Psychiatric disorders, such as depression, anxiety, alcohol or drug dependence
  • Cognitive impairment
  • Eating disorders
  • Chronic conditions such as chronic obstructive pulmonary disease (COPD)
  • Moderate to severe frailty, now a recognised diagnosis
  • Certain drugs — for example, opiates and tricyclic antidepressants 

If the history of loss of appetite is short-lived and there are symptoms of an acute infection, then explain to the patient that their appetite will return as the infection subsides. Explore whether they have experienced a loss of their sense of taste and/or smell, which could suggest COVID-19 infection.

Coeliac disease may cause loss of appetite and change in bowel habit. Respiratory symptoms may be relevant. Patients, particularly children, with respiratory tract infections often report appetite loss.

Loss of appetite with a history of persistent night sweats will require further investigation to exclude chronic infection, HIV or haematological malignancy. Tuberculosis is a possible cause. It is not a common diagnosis in the UK, but prevalence is higher in certain parts of the country, and a history of foreign travel can also be relevant.

Cancer risk assessment tools allow GPs to work out which collection of symptoms have the highest and lowest positive predictive values, with a loss of appetite featuring on many of these.1

Frailty, psychological conditions and cancer

Patients with a chronic illness such as COPD may have a reduced appetite.

A loss of appetite can also occur with moderate or severe frailty, and is common in advanced dementia. With features of cognitive impairment, such as significant memory disturbance affecting function, consider referral to a memory clinic.

Symptoms pointing to a psychological aetiology may include:

  • persistent low mood
  • early morning awakening
  • weight loss
  • anergia
  • loss of concentration
  • anhedonia
  • helplessness and hopelessness.

If there is evidence of depression, a risk assessment is essential.

Ask the patient how much they drink, as alcohol-dependent patients have reduced appetites.

Questions to ask in remote consultation
Via video link, it may be possible to observe for signs of cachexia, or weight loss, if you know the patient.

It may become apparent that there is an underlying cognitive impairment. Certain conditions, such as depression or alcohol dependence, may have some features that can be identified either over the phone or via video link — for example, flat affect or slow speech.

Face-to-face consultation
If a direct face-to-face consultation is needed, then wear appropriate PPE.2

Observe for signs of cachexia. Note any evidence of cognitive impairment or flat affect.

The remaining examination will be guided by the history. A full gastroenterological examination may be required. If the patient has odynophagia, examination of the neck and throat may be necessary. You may also wish to check for any abdominal organomegaly and palpate for lymph nodes.

It is important to weigh the patient and calculate a body mass index (BMI). Compare this with any previous values in their records. If performing the examination remotely, ask whether the patient, or a relative or carer, can provide an updated BMI using a BMI calculator.

Further investigations

Further investigations include:

  • Blood tests — for example, FBC, LFTs, U&Es, ESR, coeliac screen, HIV serology
  • Helicobacter pylori stool antigen, if there is evidence of dyspepsia
  • Chest X-ray, if clinically indicated
  • Ultrasound scan of the abdomen, if indicated. More detailed imaging — such as an urgent CT of the chest, abdomen and pelvis — may be required, but referral from primary care will be dictated by local availability
  • Depression screening
  • An alcohol-use questionnaire
  • An MMSE, or equivalent, cognitive test, for example Six-Item Cognitive Impairment Test (6CIT) or GP assessment of cognition (GPCOG)
  • COVID-19 test.

Reflux disease is associated with loss of appetite. If this is of new onset in patients >55 years, urgent endoscopy may be necessary.

Lower gastrointestinal investigations may be required to exclude malignancy.3 If malignancy is suspected, refer under the two-week rule.

  • Dr Pipin Singh is a GP in Northumberland. This article was updated in May 2021.

Click here to take a test on this article and claim a certificate on MIMS Learning


  1. Cancer Research Campaign. Cancer risk assessment tools (RATS). [Accessed 19 March 2021]
  2. Public Health England. COVID-19: Infection prevention and control. Updated 21 January 2021.
  3. NICE. Suspected cancer: recognition and referral. NG12. June 2015, updated January 2021.

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