Common symptoms of high ammonia:

High ammonia symptoms – tired emoji

Feeling very tired
or sluggish

High ammonia symptoms – zoning out emoji

Staring or
"zoning out"

High ammonia symptoms – nausea emoji

or vomiting

Urea Cycle Disorder symptoms – hallucinating emoji

Losing touch with

Urea Cycle Disorder symptoms – irritable emoji

Unusually irritable
or uncooperative

Urea Cycle Disorder symptoms – aggressive emoji


Hyperammonemia symptoms – lack of appetite emoji

Lack of appetite

Hyperammonemia symptoms – slurring emoji

Slurring words

Hyperammonemia symptoms – headache emoji


Symptoms of a urea cycle disorder (UCD) may appear at any time and can vary from person to person. Normal things in life, like being sick, stressed out, and eating foods that are high in protein, can cause ammonia to rise to toxic levels. This can trigger a hyperammonemic crisis. A hyperammonemic crisis is when there are extremely high levels of ammonia in the blood, and it requires immediate medical attention. Even mild symptoms can mean that ammonia levels in the body have risen to a high level, which can lead to serious health problems if not treated.

Symptoms like these should not be ignored, because they may be signs of high levels of ammonia which can lead to coma or permanent brain damage.

Experiencing Symptoms?

Ornithine transcarbamylase deficiency or OTC deficiency is the most common type of UCD. People with OTC may experience headaches, mental fogginess, or avoid protein, and could be signs of something serious.

Take this survey and discuss the results with your doctor. 

Take the survey (5 minutes)

Signs of a Crisis Video

Learn more about the 3 common signs of a hyperammonemic crisis.

Read transcript

One of the most important concerns that we have with patients with a urea cycle disorder is that their chronic exposure to ammonia or having high levels of ammonia, and that ammonia builds up and affects your brain. A hyperammonemic crisis is when your body starts breaking down protein and building up ammonia. That build up can lead to toxic levels of ammonia, leading to a crisis that could potentially end up in coma or brain damage. The 3 most common signs of hyperammonemia in a patient with a urea cycle disorder include a headache, vomiting, and increased sleepiness. If you think you’re experiencing a hyperammonemic crisis you should call your emergency phone number for your metabolic team immediately and head to the emergency room. 

How Well Are You Managing Your Ammonia Levels?

Get a deeper understanding of the genetics of UCDs

Learn more

Find out more about UCD treatment options

Start now