Below is an instruction from Human. Write a response.
    ### Instruction:
    What causes Sialadenitis ?
    ### Response:
    What causes sialadenitis? Sialadenitis usually occurs after hyposecretion (reduced flow from the salivary glands) or duct obstruction, but may develop without an obvious cause. Saliva flow can be reduced in people who are sick or recovering from surgery, or people who are dehydrated, malnourished, or immunosuppressed.
    