Overview
Severe acute malnutrition, which WHO now calls severe wasting and nutritional oedema, is when a child becomes dangerously thin for their height, or swells with fluid, because their body is not getting the nutrition it needs. It usually results from too little food, illness, or the two together.
It is a medical emergency and it is treatable. Most children can now be treated at home with ready-to-use therapeutic food, provided they can still eat and have no medical complications.
Disease Summary
- Category
- Non-Communicable Disease
- Cause
- Insufficient food intake, illness, or both together
- Transmission
- Not transmissible
- Body System
- Whole Body
- Preventable
- Yes
- Curable
- Yes
Symptoms
Common Symptoms
Health workers identify severe acute malnutrition using three measurements. Any one of them is enough to refer a child for full assessment.
Very Low Weight for Height
WHO defines severe wasting as weight-for-height more than three standard deviations below the median of the WHO Child Growth Standards.
A Mid-Upper Arm Circumference Below 115 Millimetres
Measured with a simple tape around the upper arm in children aged 6 to 59 months. WHO uses this threshold because it needs no scale or height board.
Swelling of Both Feet
WHO lists swelling of both feet that leaves a pit when pressed as a criterion in its own right, whatever the child’s weight or arm measurement.
Visible Wasting
Loss of muscle and fat, most obvious over the ribs, the shoulders and the buttocks.
Poor Appetite or Refusing to Eat
WHO’s care pathway turns on the appetite test. A child who can eat is treated at home, a child who cannot needs inpatient care.
Listlessness and Lack of Interest
Severely malnourished children are often quiet, withdrawn and uninterested in play, which is easily mistaken for being well behaved.
Changes in Hair and Skin
Thin, pale or easily pulled-out hair and flaking skin are recognised signs.
Frequent Infections
Malnutrition weakens the immune system, so recurring diarrhoea and chest infections are common and are often what brings the child to attention.
Danger Signs
Seek urgent medical attention immediately if any of the following symptoms develop.
Failing the Appetite Test
WHO states that a child with poor appetite must be treated as an inpatient. Being unable to eat is the most important single danger sign.
Severe Swelling of Both Feet and Legs
WHO states that severe swelling requires inpatient care regardless of anything else.
Any Danger Sign of Serious Illness
Unable to drink or breastfeed, vomiting everything, convulsions, lethargy or unconsciousness. Any of these means hospital.
Fast or Difficult Breathing
Pneumonia is common in severely malnourished children and the usual signs may be muted, so any breathing difficulty is taken seriously.
Low Body Temperature or Low Blood Sugar
Severely malnourished children lose heat and run out of sugar easily. Both are dangerous and both are looked for on admission.
Eye Changes or Difficulty Seeing
Vitamin A deficiency alongside malnutrition can cause permanent blindness and is treated urgently.
Diagnosis
The Three WHO Criteria
WHO states that a child aged 6 to 59 months with a mid-upper arm circumference below 115 millimetres, or a weight-for-height more than three standard deviations below the median, or swelling of both feet, should be referred for full assessment. Any one is enough.
Measuring the Arm
A colour-coded tape around the upper arm. This is the tool community health workers use, because it requires no equipment and can be taught quickly.
Weighing and Measuring Height
Weight-for-height is compared against the WHO Child Growth Standards, which is how wasting is graded.
Checking for Swelling
Pressing on both feet for a few seconds to see whether a pit remains. Swelling on both sides classifies a child as severely malnourished on its own.
The Appetite Test and Clinical Assessment
WHO states that children who pass the appetite test and are clinically well are treated as outpatients, while those with medical complications, severe swelling, poor appetite or danger signs are treated as inpatients.
Laboratory Tests
Mid-Upper Arm Circumference
A reading below 115 millimetres in a child aged 6 to 59 months identifies severe acute malnutrition and triggers referral.
Weight and Height Measurement
Weight-for-height more than three standard deviations below the median of the WHO Child Growth Standards identifies severe wasting.
Blood Sugar Test
Low blood sugar is common and dangerous in severe malnutrition, and is checked and corrected on admission.
Haemoglobin Test
Anaemia frequently accompanies severe malnutrition and affects how the child is managed.
Tests for Infection
Malaria, tuberculosis, HIV and other infections are looked for, because they both cause and complicate malnutrition.
Treatment
Outpatient Treatment With Ready-to-Use Therapeutic Food
WHO states that children with severe acute malnutrition who pass the appetite test and are clinically well should be treated as outpatients. Ready-to-use therapeutic food is an energy-dense paste that needs no water or cooking, which is what made home treatment possible.
Inpatient Care for Complicated Cases
WHO states that children with medical complications, severe swelling, poor appetite or danger signs should be treated as inpatients, with therapeutic milk feeds, careful rehydration and treatment of infection.
Routine Antibiotics
WHO includes antibiotics in the management of severe acute malnutrition, because infection is common and its usual signs may be absent.
Vitamin A and Micronutrients
WHO addresses vitamin A supplementation within the management of severe acute malnutrition. Vitamin A deficiency alongside malnutrition can cause blindness.
Careful Transition Back to Family Food
WHO addresses transition feeding specifically. Moving too fast is dangerous, so the change from therapeutic food to family food is made gradually.
Prevention
Exclusive breastfeeding for the first six months
Breast milk alone provides everything a baby needs for six months and protects against the infections that drive malnutrition.
Good complementary feeding from six months
Continued breastfeeding alongside adequate, varied and frequent family food is what prevents wasting in the second half of infancy.
Keep vaccinations up to date
Measles, pneumonia and diarrhoeal illness all drive children into malnutrition, and all are preventable.
Regular growth monitoring
Measuring weight and arm circumference at routine visits finds faltering growth before it becomes severe.
Safe water, sanitation and handwashing
Repeated diarrhoea is one of the main routes into malnutrition, and it is prevented by clean water and hygiene.
Treat infections promptly
Malaria, diarrhoea and chest infections all cause weight loss. Treating them quickly prevents the spiral.
Risk Factors
Children Aged 6 to 59 Months
WHO's identification criteria are written specifically for this age band.
- Children between 6 months and 5 years
- The period when breastfeeding alone is no longer enough
- Children whose complementary feeding started late or is inadequate
- Children in households where food is short or the diet is not varied
Children With Repeated Illness
Infection and malnutrition reinforce each other.
- Children with repeated diarrhoea
- Children with malaria or tuberculosis
- Children living with HIV
- Children who have recently had measles
Children in Food-Insecure and Displaced Households
WHO reports that Africa carries a substantial share of the global burden of severe wasting.
- Households facing drought, crop failure or rising food prices
- Displaced families and those in humanitarian settings
- Households where the mother is herself undernourished
- Communities far from a clinic that can identify and treat wasting
Complications
Overwhelming Infection
The immune system is weakened, so ordinary infections become life threatening and their usual warning signs may be absent.
Dehydration and Salt Imbalance
Rehydrating a severely malnourished child requires a different approach from a well-nourished one, which is why WHO addresses fluid management specifically.
Low Blood Sugar and Low Body Temperature
Both are common, both are dangerous and both are looked for and corrected on admission.
Blindness From Vitamin A Deficiency
Permanent loss of sight can follow, which is why vitamin A is part of the treatment protocol.
Lasting Effects on Growth and Development
Severe malnutrition in early childhood can affect physical growth and learning for life, even after nutritional recovery.
Death
WHO states that nearly half of deaths among children under five are linked to undernutrition.
When to Seek Medical Care
If the Arm Tape Reads in the Red Zone
A mid-upper arm circumference below 115 millimetres means the child needs full assessment the same day.
If Both Feet Are Swollen
Swelling of both feet is severe acute malnutrition whatever the child’s weight, and needs assessment immediately.
If the Child Will Not Eat
A child who is not eating needs inpatient care. This is the most important single danger sign.
Any Danger Sign of Serious Illness
Unable to drink or breastfeed, vomiting everything, convulsions, unusual sleepiness or difficulty waking.
If a Child Is Losing Weight or Not Growing
Do not wait for the child to look severely thin. Faltering growth is far easier to reverse than severe wasting.
Prognosis
Most Children Recover With Treatment
With the right therapeutic food and treatment of infection, most children recover over several weeks.
Home Treatment Works for Most Children
WHO states that children who pass the appetite test and are clinically well can be treated as outpatients, which has transformed how many children can be reached.
Complicated Cases Carry Real Risk
Children admitted with infection, severe swelling or inability to eat have a much higher risk of death, which is why early identification matters so much.
Some Effects Last
Severe malnutrition in early childhood can affect growth and learning even after nutritional recovery, which is the strongest argument for prevention.
Differential Diagnosis
Weight Loss From Chronic Infection
Tuberculosis and HIV both cause wasting, and both are looked for in any severely malnourished child.
Swelling From Kidney or Liver Disease
These also cause swelling in children and are separated by urine and blood tests.
Absorption Problems
Conditions that prevent food being absorbed cause weight loss despite adequate eating, and need separate investigation.
Stunting Rather Than Wasting
A child who is short for their age but proportionate has a different problem, reflecting long-term rather than recent undernutrition.
Feeding Difficulty From Another Condition
Cleft palate, neurological conditions and severe illness can all prevent a child eating enough, and the underlying cause needs addressing too.
References
World Health Organization: Malnutrition
WHO fact sheet defining wasting, stunting and the other forms of malnutrition, with global figures.
World Health Organization: Identification of severe acute malnutrition in children 6 to 59 months of age
The WHO criteria for identifying severe acute malnutrition and referring for assessment.
World Health Organization: WHO issues new guideline to tackle acute malnutrition in children under five
WHO’s 2023 guideline on preventing and managing wasting and nutritional oedema.
World Health Organization: Child growth standards
The growth standards against which wasting and stunting are measured.
Frequently Asked Questions
How do I know if a child is severely malnourished?
WHO uses three measurements in children aged 6 to 59 months: a mid-upper arm circumference below 115 millimetres, a weight-for-height more than three standard deviations below the median of the WHO Child Growth Standards, or swelling of both feet. Any one of the three is enough to refer the child for full assessment.
Can a severely malnourished child be treated at home?
Often yes. WHO states that children who pass the appetite test and are clinically well and alert should be treated as outpatients with ready-to-use therapeutic food. Children with medical complications, severe swelling, poor appetite or danger signs need inpatient care.
Why can I not just give the child more food?
Because refeeding a severely malnourished child too quickly can cause dangerous shifts in body chemistry. Treatment uses specific therapeutic foods in specific amounts, and the transition back to family food is made gradually. This is why the protocol exists.
Why does a swollen child count as malnourished?
Because severe malnutrition has two forms. One is severe thinness, the other is swelling with fluid. WHO lists swelling of both feet as a criterion in its own right, regardless of the child’s weight, and children with severe swelling need inpatient care.
Can the effects be reversed?
Nutritional recovery is usually achievable with proper treatment. Some effects on growth and on learning can persist even after recovery, particularly when the malnutrition was severe or prolonged, which is why finding faltering growth early matters.