Probably not unless it was an allergic reaction that caused the overdose. Definately not if the person intentianally took too much.

1) "Read the policy carefully to understand exactly what it covers. Certain causes of death (drug overdose, botched surgery) may not be covered." Source: http://www.ehow.com/how_2090084_insure-personal-accident-injuries.html 2) "Mrs. Oldfield’s husband had life insurance through Transamerica. He swallowed 30 condoms filled with cocaine to smuggle the drugs through customs. One or more of the condoms burst and he died from cocaine poisoning." "Transamerica also argued that the ingesting of the condoms was an intentional act. Basic insurance principles allow insurers not to pay for intentional acts. The Court ruled that the death was caused by the accidental bursting of the condoms, and was not intentional." "Oldfield is one of a series of cases in which the courts, in Ontario and elsewhere, have effectively distinguished voluntary or intentional causes from intentional results, although they claim they are not doing that. Only intentional results, on this thinking, allow the insurer to avoid payment. This affects not only entitlement to recover, but how much, since many policies pay increased amounts for “accidental” deaths. Accidental in most life insurance claims is distinguished from illness. The law developed to apply to those situations really provides no guidance for situations such as these from British Columbia: - a doctor addicted to drugs overdoses. The insurer argued that a doctor ought to be aware of the risk of overdose, so if the traditional test of “foreseeable consequences” used in negligence cases applies, his intentional act caused his death. The Court ruled that he did not intend to overdose, so the negligence test did not help the insurer. “Accident” includes negligence. The Supreme Court will also review this case. - a dentist dies by asphyxiation while administering nitrous oxide to himself. This case was found to be even more obviously an accident - autoerotic asphyxiation which lead to death was compared to a child playing with a plastic bag." Source: http://www.weilers.ca/articles/130 3) "When you receive a denial of life insurance claim, you may not understand all of the relevant policy provisions, and may think the denial was reasonable. For example, in a recent case, an insurance company denied a cocaine overdose death claiming it was a suicide. We were able to persuade the judge that the death was really an accident and prevailed at trial forcing the insurance company to pay the claim. Often the insurance company will deny a claim based on an unsupportable position as in that the death was a suicide, when in fact it does not have the evidence to support the denial at trial." 4) I do not know exactly the answer to your question, but I suppose that many insurance company could refuse to pay in such a case and that you could need a good attorney to get the money (if there were a chance to get it at all). Even if there is an autopsy report, they could try to make a counter-expertise.