There are numerous possible causes for loss of appetite. If it persists then see your doctor who can try to find the cause in your particular case.
What causes a loss of appetite?
Normally most people have a regular desire to eat food - an 'appetite'. Eating is an essential part of life, giving us the energy and nutrients our bodies need to stay healthy. If you lose your appetite, there is usually a reason behind it, and it often has a medical or psychological cause. Most often, having no appetite is a short-term problem. Most of us have experienced this with a flu-like viral illness or tummy bug (gastroenteritis), or in times of extreme stress (such as an exam or a bereavement). Sometimes, however, it can go on for longer. In this case it may signify a more important medical problem.
There are many reasons why appetite may be lost. Some are serious conditions, others are not. Possible causes include:
- Infection. This includes short-term infections (such as flu, common colds, urine infections, chest infections, tummy bugs, etc) and more long-lasting infections such as tuberculosis (TB) or HIV. Usually there will be other symptoms specific to the infection.
- Medication. Many medicines can cause loss of appetite as a side-effect, including some antidepressants such as fluoxetine, methylphenidate used for ADHD, chemotherapy, some medicines for type 2 diabetes, and strong painkillers (opiates).
- Stress and anxiety.
- Depression. A loss of appetite can be a symptom of depression, along with other symptoms such as low mood, loss of concentration, and poor sleep.
- Conditions causing breathlessness. If it is difficult to breathe, it may be hard to eat at the same time as breathe. Medical conditions causing this might include chronic obstructive pulmonary disease (COPD), pneumonia, asthma, pulmonary embolus, and congestive heart failure.
- Acid reflux and indigestion.
- Problems with the mouth and teeth. Any problem which makes it difficult to chew food, swallow it or taste it might interfere with appetite. For example, toothache, poorly-fitting dentures, dental abscesses, a dry mouth, jaw dysfunction or loss of taste.
- Congestion of the nose and surrounding areas due to allergies, polyps, or infections.
- Conditions affecting the guts, including coeliac disease, Crohn's disease, ulcerative colitis, appendicitis, and diverticulitis.
- Cystic fibrosis. This is an inherited condition which can affect appetite through the damage it causes to the lungs and pancreas.
- Gallstones. These can cause severe pain particularly after eating fatty foods.
- Cancer. Many different cancers can cause loss of appetite, and many treatments for cancers cause loss of appetite. Usually lack of appetite is accompanied by other symptoms specific to that particular cancer, but sometimes loss of appetite can be an early cancer symptom.
- Diabetes mellitus.
- Underactive thyroid gland (hypothyroidism).
- Disruption to the senses. Enjoyment of eating is enhanced by seeing the food, smelling it and tasting it. So if any of these senses are lost, it can have an effect on appetite - ie if there is loss of vision, loss of taste or loss of smell.
- Alcohol excess or use of illicit drugs.
- Anorexia nervosa. Extreme weight loss and a fear of food can reduce appetite.
- Age. Appetite tends to decline as people get older, and they may naturally eat less. This may be due to another cause, such as one of the above, or due to a decline in activity. Also the stomach empties more slowly in older age, so older people may feel full for longer.
- Long-lasting (chronic) health conditions such as chronic pain, chronic kidney disease, chronic liver disease and dementia.
What should I do if I have lost my appetite?
If a loss of appetite persists, and there is no obvious reason for it, see your GP. As you can see above, there is a huge list of potential causes. Your GP will want to rule out the more serious causes - in particular, cancer.
It is particularly important to see your GP as soon as possible if you have any of the following symptoms associated with a persisting lack of appetite:
- Unintentional weight loss.
- Difficulty swallowing.
- Pain in your tummy (abdominal pain).
- Swelling of your tummy.
- Night sweats.
- Feeling sick (nausea).
- Low mood.
- Feeling out of breath.
What tests will I need?
Your GP will be able to narrow down the possible causes by asking you about your symptoms and examining you. He or she will probably suggest some blood tests, which may give clues as to the cause. An ultrasound scan of the tummy may be helpful in some cases, and/or a chest X-ray. Further tests may then be indicated depending on what the likely diagnosis seems to be.
What is the treatment?
This will entirely depend on the cause which is found. Generally speaking, the most important thing is to establish the cause so that it can be quickly treated if possible. Your appetite keeps you eating, which keeps you healthy and strong. See the separate leaflet called Healthy Eating for more information.
Further reading and references
Suspected cancer: recognition and referral; NICE Clinical Guideline (2015 - last updated July 2017)
Nicholson BD, Oke J, Friedemann Smith C, et al; The Suspected CANcer (SCAN) pathway: protocol for evaluating a new standard of care for patients with non-specific symptoms of cancer. BMJ Open. 2018 Jan 218(1):e018168. doi: 10.1136/bmjopen-2017-018168.
Pilgrim AL, Robinson SM, Sayer AA, et al; An overview of appetite decline in older people. Nurs Older People. 2015 Jun27(5):29-35. doi: 10.7748/nop.27.5.29.e697.