Caffeine doses of 200 mg or higher can cause unpleasant symptoms including nausea, headache, and irregular heartbeat, while dose of 750 - 1000 mg can cause severe toxic symptoms. Severe caffeine intoxication can result in nausea, vomiting, anxiety, tremor, seizures, tachycardia, dysrhythmias, hypotension, hypokalemia, and metabolic acidosis.

Several fatalities resulting from caffeine overdose have been documented, but they are extremely rare relative to its widespread use. In the case of a massive caffeine overdose, vomiting often protects against fatal poisoning, but some deaths have still resulted.

Fatal dose range in humans is believed to be between 3 - 20 grams, approximately the amount of caffeine found in 20 - 130 cups of drip coffee or 15-100 common caffeine tablets (200 mg each). Blood caffeine levels greater than 80 ug/mL have been associated with death, but data is limited. It is difficult to ingest such high levels of caffeine accidentally, and many of the documented fatalities appear to be suicide attempts involving the ingestion of a large number of caffeine pills.

In one extreme case a 41-year-old woman was successfully resuscitated after ingesting 50 g of caffeine (see Holstege et al., 2003 below).

Erowid editors thought they remembered a citation for a death involving 3 grams of caffeine ingested orally, but have been unable to locate documentation. The references below are for fatal and non-fatal overdose ingestions. The highest-documented survived dose is 50 grams and the lowest well-documented death listed here is from 10 grams of caffeine ingested orally. Alsott et al. (1973) report a death resulting from the ingestion of 6.5 - 12 g caffeine. If anyone knows of other well documented deaths we should include here, please let us know.

Incident: Stiner J, 18. May 27, 2014 #

Logan Stiner, 18 years old, was found unresponsive by his brother at home after ingesting an unknown amount of pure caffeine powder, possibly mixed into a drink.

Editors. "High School Senior Dies After Ingesting Toxic Amount Of Caffeine Powder". CBS Cleveland. June 30, 2014.

LAGRANGE, Ohio (CBS Cleveland) - A senior at Keystone High School was found dead after he ingested toxic amounts of caffeine powder. WJW reports that Logan Stiner, 18, was found unresponsive by his brother in their family home. Steven Evans, the Loraine County Coroner told the station that Stiner's death was a result of having toxic levels of caffeine in his blood after ingesting the powder. The overdose caused cardiac arrhythmia and a seizure.[...] Evans said that Stiner was alone when he ingested the powder, so it is not known how much he drank.

Reid M. School reeling from sudden death of stand-out senior. Fox 8 Cleveland. May 28, 2014.

LAGRANGE, Ohio - A community is reeling from the death of a high school senior just days before graduation. The halls were quiet at Keystone High School in LaGrange Wednesday. "Usually at this time of year, there is joy and anticipation. I didn't see any of that today," said teacher Phil Tuttle. That's because students and the community are mourning the death of Logan Stiner, 18, who died of natural causes at home Tuesday.

• Alstott RL, Miller AJ, Forney RB. Report of a human fatality due to caffeine. J Forensic Sci. 1973;18(2):135-7. [ Abstract ]
  An individual (age unknown) died after consuming between 6.5 and 12 g caffeine.


• Garriott JC, Simmons LM, Poklis A, Mackell MA. Five cases of fatal overdose from caffeine-containing 'look-alike' drugs. J Anal Toxicol, 1985; 9(3):141-3. [ Abstract ]
  Mixed ephedrine and caffeine fatalities, showed blood levels of 130-344 mg/L caffeine and three also had 3.5-20.5 mg/L of ephedrine.


• Holmgren P, Norden-Pettersson L, Ahlner J. Caffeine fatalities--four case reports. Forensic Sci Int, 2004; 139(1):71-3 [ Abstract ]
  Four cases reported: 54 yr old male died after taking 100 x 100 mg caffeine tablets resulting in 173 mg/L in femoral blood. 21 yr old male died after ingesting 200 x 100 mg caffeine tablets resulting in 210 mg/L in femoral blood. 31 yr old male died after ingesting 100 x 100 mg tablets resulting in 153 mg/L in blood sample. 47 yr old female died after ingesting 100 tablets containing both caffeine and ephedrine resulting in 200 mg/L of caffeine and 4.8 mg/L of ephedrine.


• Kerrigan S, Lindsey T. Fatal caffeine overdose: two case reports. Forensic Sci Int, 2005; 153(1):67-9 [ Abstract ]
  39 yr old female found dead with 192/mgL caffeine in femoral blood. 29 yr old male had taken 'a bottle of caffeine pills the day before' died while in hospital and had 567 mg / L caffeine in femoral blood.


• McGee MB. Caffeine poisoning in a 19-year-old female. J Forensic Sci. 1980 Jan;25(1):29-32. [ Abstract ]
  19 yr old female died after ingesting over the counter appetite suppresant. Dose unknown.


• Mrvos RM, Reilly PE, Dean BS, Krenzelok EP. Massive caffeine ingestion resulting in death. Vet Hum Toxicol. 1989 Dec;31(6):571-2. [ Abstract ]
  22 yr old female died after ingesting diet pills. Highest known blood levels 1,560 mg/L.


• Shum S, Seale C, Hathaway D, Chucovich V, Beard D. Acute caffeine ingestion fatalities: management issues. Vet Hum Toxicol. 1997;39(4):228-30 [ Abstract ]
  A 32 yr old female experienced multiple seizures and fatal cardiac arrest after ingesting 20 g caffeine. A 15 yr old female suffered seizures and fatal cardiac arrest after ingesting 80 caffeine tablets of unknown strength.


• Walsh I, Wasserman GS, Mestad P, Lanman RC. Near-fatal caffeine intoxication treated with peritoneal dialysis. Pediatr Emerg Care. 1987 Dec;3(4):244-9. [ Abstract ]
  2 yr old female died after orally ingesting caffeine.


• Winek CL, Wahba WW, Winek CL Jr, Balzer TW. Drug and chemical blood-level data 2001. Forensic Sci Int, 2001; 122(2-3):107-23 [ Abstract ]
  No citation is given, but Winek et al.'s comprehensive therapeutic and toxic blood level data is considered a good source. Winek et al. give "> 100 ug/ml" as the "Lethal" level for caffeine. That works out to 100 mg/L.

• Dietrich AM, Mortensen ME. Presentation and management of an acute caffeine overdose. Pediatr Emerg Care. 1990 Dec;6(4):296-8. [ Abstract ]
  Non-Fatal. 1 yr old female ingested 2-3 grams caffeine (200-300 mg/kg), showed blood levels of 385 mg/L and survived with hospital care.


• Forman J, Aizer A, Young CR. Myocardial infarction resulting from caffeine overdose in an anorectic woman. Ann Emerg Med. 1997 Jan;29(1):178-80. [ Abstract ]
  Non-Fatal. 20 yr old bulimic woman ingested 20g caffeine, did not die but suffered subendocardial infarction.


• Holstege CP, Hunter Y, Baer AB, Savory J, Bruns DE, Boyd JC. Massive caffeine overdose requiring vasopressin infusion and hemodialysis. J Toxicol Clin Toxicol. 2003;41(7):1003-7. [ Abstract ]
  
  
• Leson CL, McGuigan MA, Bryson SM. Caffeine overdose in an adolescent male. J Toxicol Clin Toxicol. 1988;26(5-6):407-15. [ Abstract ]
  Non-Fatal. 16 yr old male ingested estimated 6-8grams caffeine and survived with hospital care.