Having a family member with an opioid prescription increases a person’s risk of ending up in the emergency room with a drug overdose almost threefold, a new study suggests.

Researchers at Harvard analyzed overdoses that led to an emergency room visit or hospitalization, and looked at whether the patient’s family members had been prescribed opioids, Vox reports. They found the more opioids a family member was prescribed, the higher the risk of an overdose.

The study does not prove a cause-and-effect connection between having a family member with an opioid prescription and an increased risk of a drug overdose, the article notes. The researchers conclude that overdoses among family members of people with opioid prescriptions may be reduced by expanding access to opioid overdose medications, locking up prescription opioids, and providing greater patient education.