A formulation comprising a halogen-containing oxidiser and a gelling agent. The formulation is used for treating hazardous waste such as controlled drugs and contaminated medical waste such as discarded blood products, sharps or other materials that have contacted bodily fluids. The waste may originate from hospitals, clinics, veterinary clinics, pharmacies or tattoo studios. The halogen containing oxidiser may be selected from calcium hypochlorite, calcium hypobromite, sodium hypochlorite, sodium hypobromite, sodium bromated and barium hypochlorite. The gelling agent is ideally a super absorbent polymer such as polyacrylate or polyacrylate salts, a natural gum or organic starch. The formulation may include a taste deterrent, dye, activated carbon and desiccant. Ideally, the formulation is supplied as a powder which is combined with water. The formulation may form part of a drug denaturing kit. A method of use is also disclosed.