<unk>  is<unk>  that results from exposure to any of a number of forms of<unk> . Early symptoms include headache, dizziness, fast heart rate, shortness of breath, and vomiting. This phase may then be followed by seizures, slow heart rate, low blood pressure, loss of consciousness, and cardiac arrest. Onset of symptoms usually occurs within a few minutes. Some survivors have long-term neurological problems. Toxic<unk> -containing compounds include hydrogen<unk>  gas and a number of<unk>  salts.<unk>  is relatively common following breathing in smoke from a house fire. Other potential routes of exposure include workplaces involved in metal polishing, certain insecticides, the medication sodium nitroprusside, and certain seeds such as those of apples and apricots. Liquid forms of<unk>  can be absorbed through the skin.<unk>  ions interfere with cellular respiration, resulting in the body's tissues being unable to use oxygen. Diagnosis is often difficult. It may be suspected in a person following a house fire who has a decreased level of consciousness, low blood pressure, or high lactic acid. Blood levels of<unk>  can be measured but take time. Levels of 0.5–1 mg/L are mild, 1–2 mg/L are moderate, 2–3 mg/L are severe, and greater than 3 mg/L generally result in death. If exposure is suspected, the person should be removed from the source of exposure and decontaminated. Treatment involves supportive care and giving the person 100% oxygen. Hydroxocobalamin (vitamin B12a) appears to be useful as an antidote and is generally first-line. Sodium thiosulphate may also be given. Historically<unk>  has been used for mass suicide and by the Nazis for genocide.
Cyanide poisoning
Foreign body aspiration
Chlorine gas poisoning
Carbon monoxide poisoning
Salicylate poisoning
Nitrogen dioxide poisoning
Strychnine poisoning
Tin poisoning