Yes, typically death from an accidental overdose of illegal drugs would be excluded from an accidental death and dismemberment (AD&D) insurance policy.
AD&D pays out if you die in an accident or suffer a terrible injury. The policy pays the full benefit for accidental death (like a car crash) and a specified payment for injury, such as loss of a hand, loss of a foot or loss of hearing or sight. Some policies also cover paralysis or coma. The payments are in addition to benefits you or your beneficiary would get from other coverage, such as life, health, workers compensation or disability insurance.
However, AD&D policies generally exclude coverage for death or injuries caused by self-inflicted harm, commission of a felony by the insured, active duty or training in the military, and intoxication or illegal drug use — even if the overdose wasn’t intentional.
Some policies also contain other exclusions, such as losses that occur when the insured is piloting an aircraft or working as a flight attendant. However, accidental death or injury from a plane crash would be covered if you were a passenger on a commercial flight.
For more, see The basics of accidental death and dismemberment insurance.