Hypervitaminosis A refers to the toxic effects of ingesting too much preformed vitamin A (retinyl esters, retinol, and retinal). Symptoms arise as a result of altered bone metabolism and altered metabolism of other fat-soluble vitamins. Hypervitaminosis A is believed to have occurred in early humans, and the problem has persisted throughout human history. Toxicity results from ingesting too much preformed vitamin A from foods (such as fish liver or animal liver), supplements, or prescription medications and can be prevented by ingesting no more than the recommended daily amount. Diagnosis can be difficult, as serum retinol is not sensitive to toxic levels of vitamin A, but there are effective tests available. Hypervitaminosis A is usually treated by stopping intake of the offending food(s), supplement(s), or medication. Most people make a full recovery. High intake of provitamin carotenoids (such as beta-carotene) from vegetables and fruits does not cause hypervitaminosis A. Signs and symptoms
Symptoms may include:

Causes
Hypervitaminosis A results from excessive intake of preformed vitamin A. Genetic variations in tolerance to vitamin A intake may occur, so the toxic dose will not be the same for everyone. Children are particularly sensitive to vitamin A, with daily intakes of 1500 IU/kg body weight reportedly leading to toxicity. Types of vitamin A
It is "largely impossible" for provitamin carotenoids, such as beta-carotene, to cause toxicity, as their conversion to retinol is highly regulated. No vitamin A toxicity has ever been reported from ingestion of excessive amounts.
Thallium figures prominently in the 1995 film The Young Poisoners Handbook, a dark comedy loosely based on the life of Graham Frederick Young. In Big Nothing, Josie is the Wyoming Widow; a murderer who befriended men and killed them with whiskey laced with highly concentrated thallium. In the 2007 episode "Whatever It Takes" of House, a character uses thallium to poison a patient to mimic the effects of polio, then appear to cure it with ultra-high doses of vitamin C.
In the NCIS episode "Dead Man Walking" (2007), thallium-laced cigars are used to murder a Naval officer. "Page Turner", a 2008 episode of CSI: NY, has radioactive thallium poisoning as its central theme. In the 2010 film Edge of Darkness, thallium is used to poison both the main character and his daughter. In the 2015 James Bond film Spectre, the organisation of the same name used thallium to poison Mr. White by lacing his mobile phone with it. In Season 3 of Royal Pains, the mysterious German billionaire Boris Kuester von Jurgens-Ratenicz was poisoned by thallium added to his pools water. In Drop Dead Diva episode "Ashes to Ashes", thallium was used to murder a clients husband, affecting the client when she ate the cremation remains. In the 2016 TVB drama Two Steps From Heaven, thallium was used to poison Bosco Wongs character. In S6:E10 of the Father Brown Series, Hercule Flambeaus wife poisons Father Brown with thallium in order to induce Flambeau to exchange a religious relic for her giving Brown the antidote.