"Unless palliative care becomes available near their homes, these people will continue to die in horrific circumstances when they fall ill with cancer or other chronic illnesses," the report said.
Senegal's National Pharmacy says it has added oral morphine tablets to its 2012 essential medicines list and plans to begin importing more of it later this year.
Government regulations, though, still require patients to get the drug from only a limited number of regional and national hospitals. Restrictions on prescriptions also mean families must refill morphine weekly.
And even when family members do make the journey, sometimes they find the drug is not in stock. Only a handful of places have oral morphine at all, and the report found the "complication authorization and important process creates many opportunities for delays."
Alboury Seck told HRW during one morphine shortage he sent a relative abroad in hopes he could bring back some of the drug. He rationed his remaining pills but nothing else could keep the pain from advanced prostate cancer at bay.
"I tried to bear the pain for two to three days, and when I could not handle it, I would take one pill," he said. "I went to all the pharmacies and they do not sell it. I tried to use Tylenol, Motrin, it is the only thing I have with me. Two, three, four times a day, but it is not enough. Only the morphine works."