[4] Other aspects of thallium's chemistry differ strongly from that of the alkali metals, such as its high affinity for sulfur ligands.

Thus this substitution disrupts many cellular processes by interfering with the function of proteins that incorporate cysteine, an amino acid containing sulfur.

Among the distinctive effects of thallium poisoning are peripheral nerve damage (victims may experience a sensation of "walking on hot coals") and hair loss (which led to its initial use as a depilatory before its toxicity was properly appreciated).

These include: tremors, headache, insomnia, seizures, ataxia, ascending peripheral neuropathies, coma, and possible death.

After many weeks, those with thallium poisoning begin to present with dermatological symptoms such as acne-like abrasions, hypohidrosis, and alopecia.

Thallium may be measured in blood or urine as a diagnostic tool in clinical poisoning situations or to aid in the medicolegal investigation of suspicious deaths.

Normal background blood and urine concentrations in healthy persons are usually less than 1 μg/litre, but they are often in the 1–10 mg/litre range (1,000–10,000 times higher) in survivors of acute intoxication.

The first known was to use Prussian blue (potassium ferric hexacyanoferrate), which is a solid ion exchange material, and absorbs thallium.