Over time, poor appetite can contribute to unintended weight loss, muscle loss, and nutritional deficiencies.
This can create a cycle in which declining nutritional status makes fatigue and weakness worse.
However, appetite changes have many possible causes, including infections, digestive disorders, medication side effects, depression, cancer, and hormonal conditions.
Persistent loss of appetite, particularly when accompanied by unexplained weight loss or other symptoms, should be medically evaluated.
13. Nausea and Vomiting
Nausea can occur in advanced kidney disease when waste products accumulate in the bloodstream.
This is sometimes associated with uremia, a serious condition involving the buildup of substances that healthy kidneys would normally remove.
People may experience nausea after meals, an unpleasant sensation in the stomach, or occasional vomiting.
In severe cases, nausea can become persistent and interfere with eating and drinking.
However, nausea and vomiting are common symptoms with many possible causes, including food poisoning, gastrointestinal infections, pregnancy, medication reactions, and digestive conditions.
Persistent vomiting can also cause dehydration, which may further impair kidney function.
If vomiting is severe, accompanied by reduced urination, confusion, significant weakness, or an inability to keep fluids down, seek urgent medical attention.
14. A Metallic Taste in the Mouth
Some people with advanced kidney disease report an unusual metallic taste.
They may describe food as tasting different, notice an unpleasant flavor in their mouth, or experience a persistent sensation similar to having metal on the tongue.
This may be related to the accumulation of waste products in the bloodstream and changes in saliva composition.
In some cases, altered taste can make food less appealing and contribute to reduced appetite.
However, metallic taste is not specific to kidney disease.
Dental problems, gum disease, oral infections, certain medications, acid reflux, and nutritional deficiencies can also cause changes in taste.
If the symptom persists, especially alongside other unexplained changes, it is worth discussing with a healthcare professional.
15. Persistent Bad Breath
Unpleasant breath can occasionally be associated with advanced kidney disease.
When waste products accumulate in the bloodstream, some substances may affect the breath and produce an unusual odor.
In people with severe uremia, breath may have an ammonia-like or urine-like smell.
This is sometimes referred to as uremic fetor.
However, persistent bad breath is far more commonly associated with dental and oral health problems, including gum disease, tooth decay, dry mouth, and bacterial buildup on the tongue.
Tonsil stones, sinus infections, smoking, and digestive conditions can also contribute.
Bad breath alone is not a useful diagnostic test for kidney disease.
If it occurs alongside nausea, appetite loss, itching, swelling, or changes in urination, medical evaluation becomes more important.
16. Difficulty Concentrating or Mental Fog
The kidneys help maintain the chemical balance necessary for normal brain function.
In advanced kidney disease, the buildup of waste products, electrolyte disturbances, anemia, and sleep disruption may contribute to cognitive difficulties.
Some people experience what they describe as mental fog.
They may find it harder to concentrate, remember details, follow conversations, or complete familiar tasks.
These changes can be gradual and may initially be mistaken for stress, poor sleep, or normal aging.
However, mental confusion can have many causes, including medication effects, infections, low blood sugar, neurological disorders, and dehydration.
Sudden confusion, disorientation, seizures, or difficulty staying awake is a medical emergency and should not be assumed to be a routine symptom of chronic kidney disease.
17. Difficulty Sleeping
Sleep problems are common among people with chronic kidney disease.
Several factors may contribute, including itching, muscle cramps, frequent nighttime urination, restless legs, pain, and sleep apnea.
Some people struggle to fall asleep, while others wake repeatedly during the night and feel unrefreshed in the morning.
Advanced kidney disease may also be associated with changes in the body's internal balance that can interfere with normal sleep patterns.
Restless legs syndrome is particularly relevant. It produces an uncomfortable urge to move the legs, often becoming worse during periods of rest or in the evening.
Although sleep problems can occur in kidney disease, they are also associated with anxiety, depression, caffeine, chronic pain, and many other conditions.
Persistent sleep disturbances should be discussed with a healthcare professional, particularly when they occur with other possible kidney-related symptoms.
18. Unexplained Weight Loss
Unexpected weight loss can sometimes occur in people with advanced kidney disease.
Reduced appetite, nausea, changes in taste, inflammation, and metabolic disturbances can make it difficult to maintain adequate nutrition.
Some individuals gradually lose muscle mass and body weight without intentionally changing their diet or exercise habits.
This is particularly concerning when weight loss occurs alongside persistent fatigue, weakness, or reduced appetite.
However, unexplained weight loss has many possible causes, including thyroid disorders, diabetes, digestive diseases, infections, and certain cancers.
A person who loses weight without trying should not assume kidney disease is responsible.
A medical assessment can help identify the underlying cause and determine whether kidney testing is appropriate.
19. High Blood Pressure That Is Difficult to Control
High blood pressure and kidney disease are closely connected.
The kidneys help regulate blood pressure by controlling fluid balance and releasing hormones involved in blood vessel regulation.
When kidney tissue becomes damaged, these processes may become disrupted, contributing to elevated blood pressure.
At the same time, long-term high blood pressure can damage the small blood vessels inside the kidneys, reducing their ability to filter blood effectively.
This creates a harmful cycle: kidney damage can worsen blood pressure, while uncontrolled blood pressure can cause additional kidney damage.
Some people have no obvious symptoms of high blood pressure, even when their readings are dangerously elevated.
That is why regular blood pressure measurement is important, especially for individuals with diabetes, obesity, a family history of kidney disease, or existing cardiovascular conditions.
If blood pressure remains difficult to control despite treatment, healthcare professionals may investigate whether kidney disease or another underlying condition is contributing.
20. Persistent Back or Flank Pain
Pain in the back or side of the body can sometimes be associated with kidney or urinary tract conditions.
The kidneys are located toward the back of the upper abdomen, on either side of the spine.