Symptoms may include a tremor, increased reflexes, trouble walking, kidney problems, and an altered level of consciousness.

[1] Decreased excretion may occur as a result of dehydration such as from vomiting or diarrhea, a low sodium diet, or from kidney problems.

[1] Mild symptoms include nausea, feeling tired, and tremor occur at a level of 1.5 to 2.5 mEq/L in blood serum.

Moderate symptoms include confusion, an increased heart rate, and low muscle tone occur at a level of 2.5 to 3.5 mEq/L.

[1] Severe symptoms include coma, seizures, low blood pressure and increased body temperature which occur at a lithium concentration greater than 3.5 mEq/L.

[1] When lithium overdoses produce neurological deficits or cardiac toxicity, the symptoms are considered serious and can be fatal.

[5] In acute toxicity, people have primarily gastrointestinal symptoms such as vomiting and diarrhea, which may result in volume depletion.

During acute toxicity, lithium distributes later into the central nervous system causing dizziness and other mild neurological symptoms.

[6] In chronic toxicity, people have primarily neurological symptoms which include nystagmus, tremor, hyperreflexia, ataxia, and change in mental status.

[13] The drug itself is also known to be nephrotoxic, opening up the possibility of spontaneous emergence of toxicity at doses that were previously well-tolerated.