6 Bible Verses about Demons Causing Illness

One of the crowd replied to Him, “Teacher, I brought You my son, possessed with a spirit which makes him unable to speak; and whenever it seizes him [intending to do harm], it throws him down, and he foams [at the mouth], and grinds his teeth and becomes stiff. I told Your disciples to drive it out, and they could not do it.” He replied, “O unbelieving (faithless) generation, how long shall I be with you? How long shall I put up with you? Bring him to Me!” read more.
They brought the boy to Him. When the [demonic] spirit saw Him, immediately it threw the boy into a convulsion, and falling to the ground he began rolling around and foaming at the mouth. Jesus asked his father, “How long has this been happening to him?” And he answered, “Since childhood. The demon has often thrown him both into fire and into water, intending to kill him. But if You can do anything, take pity on us and help us!” Jesus said to him, “[You say to Me,] ‘If You can?’ All things are possible for the one who believes and trusts [in Me]!” Immediately the father of the boy cried out [with a desperate, piercing cry], saying, “I do believe; help [me overcome] my unbelief.” When Jesus saw that a crowd was rapidly gathering [around them], He rebuked the unclean spirit, saying to it, “You deaf and mute spirit, I command you, come out of him and never enter him again!” After screaming out and throwing him into a terrible convulsion, it came out. The boy looked so much like a corpse [so still and pale] that many [of the spectators] said, “He is dead!” But Jesus took him by the hand and raised him; and he stood up.

When they approached the crowd, a man came up to Jesus, kneeling before Him and saying, “Lord, have mercy on my son, for he is a lunatic (moonstruck) and suffers terribly; for he often falls into the fire and often into the water. And I brought him to Your disciples, and they were not able to heal him.” read more.
And Jesus answered, “You unbelieving and perverted generation, how long shall I be with you? How long shall I put up with you? Bring him here to Me.” Jesus rebuked the demon, and it came out of him, and the boy was healed at once.

On the next day, when they came down from the mountain, a large crowd met Him. And a man from the crowd shouted for help, “Teacher, I beg You to look at my son, because he is my only child; and a spirit seizes him, and suddenly he cries out, and it throws him into a convulsion so that he foams at the mouth; and only with [great] difficulty does it leave him, mauling and bruising him as it leaves. read more.
I begged Your disciples to cast it out, but they could not.” Jesus answered, “You unbelieving and perverted generation! How long shall I be with you and put up with you? Bring your son here [to Me].” Even while the boy was coming, the demon slammed him down and threw him into a [violent] convulsion. But Jesus rebuked the unclean spirit, and healed the boy and gave him back to his father.

While they were going away, a mute, demon-possessed man was brought to Jesus. And when the demon was driven out [by Jesus], the mute man spoke; and the crowds wondered in amazement, saying, “Never before has anything like this [miracle] been seen in Israel.”

And [at another time] Jesus was casting out a demon, and it was [controlling a man so as to make him] mute; when the demon had gone out, the mute man spoke. And the crowds were awed.

And there was a woman who for eighteen years had had an illness caused by a spirit (demon). She was bent double, and could not straighten up at all.