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Can Demons Cause Physical Illness?

August 1, 2013 by  
Filed under Demonology, Fr. Fortea, Spiritual Warfare

Dear Fr. Fortea, can a demon cause a physical illness?

First, we need to clearly understand that physical illnesses nearly always have natural causes. The belief that sickness has its cause in the demonic world is rooted in a pre-scientific, superstitious Can Demons Cause Physical Illnessworldview in which myth is substituted for reason. This being said, if demons exist, then the possibility exists that they may sometimes act to cause illness, but this is an extraordinary occurrence – i.e., it is outside the normal laws of nature. Normally only rain, snow, or hail fall from the sky, but meteorites also fall on rare occasions. It is the same case here; sometimes strange events happen.

St. Thérèse of Lisieux includes a very interesting chapter in her autobiography:

The illness which overtook me came, certainly, from the demon; furious because of your entry into the Carmel [i.e., of her sister], he was determined to take revenge on me due to all the damage that our family would cause him in the future, but he almost made me not to suffer; I went on with my schoolwork, and nobody was worried about me. It was towards the end of that year that I was attacked by a continual headache. This lasted until the Easter of 1883 … it was while I was undressing that I had a strange fit of trembling … I wish I could describe this strange illness of mine. I’m fully persuaded now, that it was the work of the devil … I was delirious nearly all the time and talking utter nonsense … often I seemed to be in a dead faint, without making the slightest movement … it seems to me that the demon had been given power over the outward part of me, but couldn’t reach neither my soul, nor my spirit, except by inspiring me very great fears of certain things. (“Story of a Soul”, chapter 3)

In an extraordinary and unusual way, God can allow a demon to cause a physical illness in a human being. In fact, St. Luke expressly mentions such a case: “And there was a woman who had had a spirit of infirmity for eighteen years; she was bent over and could not fully straighten herself”  (Luke 13:11). The Gospel text does not explicitly say that this woman was possessed but that a “spirit of infirmity” (i.e., a demon) was the cause of her sickness. To this, we can add the sickness of Job and the death of Sarah’s spouses caused by the demon Asmodeus in the book of Tobit, as well as the torments of such modern saints as St. John Vianney, the Curé of Ars.



Editor’s Note:  To learn more about spiritual warfare and demonology, Catholic Spiritual Direction recommends Fr. Fortea’s excellent book, Interview With An Exorcist – An Insider’s Look at the Devil, Demonic Possession, and the Path to Deliverance.

Art: Dragon detail from Die Unbefleckte Empfängnis (The Immaculate Conception), Giovanni Battista Tiepolo, 1767-1768, PD-US author's life plus 100 years or less, Wikimedia Commons.

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About Fr. Jose Antonio Fortea

Father José Antonio Fortea is not only an exorcist, but also a writer, and parish priest. He once thought he would lead what he has termed ordinary life as an attorney in Madrid, much as his father did before him, but sensed instead a vocation to the priesthood in his adolescent years. A theology graduate of Navarre University in Spain, Father Fortea wrote a thesis there on exorcism. He has been a practicing exorcist for several decades.

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  • Yule

    Sin can cause disease too… I am interested to know more about family tree, wherein a disease or sickness runs into the family because of the previous sins by former generation, maybe it’s the demon that causes it…

    • Dom C

      Fr. Yosefu Ssemekula has book out called The Healing of Families that discusses what you mention, Yule. Pretty interesting stuff — we attended a workshop at Denver’s largest parish on it a while back.

  • patricia

    There is spiritual warfare and I noticed myself every time I try to grow closer to God or serve him I get physically ill. I began to doubt Gods will for me. The action of the Holy Spirit. I become fearful and with dread. So maybe it’s a good sign if I am physically sick and yet striving towards deeper union with God then I should not worry but keep focused on Christ?

    • LizEst

      You are right to keep your focus on Christ even when you are physically sick, and especially when you are physically sick. Yes, it is a good sign if you are focused on Christ in these circumstances. Christ himself tells us not to worry and not to be afraid for He is with us always. This is the example of many saints who have undergone such trials. God bless you, Patricia! I’m praying for you.

      • patricia

        Thank you Liz pray I get some sleep I pulled a muscle in my back and shoulder when I was stretching I had a severe cough. This week will be the first week in along time that I am able to make Mass Monday thru Friday our parish does not have a Saturday Mass. I notice the difference when I do go to mass sick or not. I realize I need Jesus every single day!!!

        • LizEst

          Yes, Patricia, every Mass and every communion strengthens you.

  • Mary G

    Just wondering why the exorcist used the words: “IF demons exist”..(my emphasis on the “if”). 😯 Also, it occured to me that all illness is indirectly caused by the devil, because of original sin. In this broken world, which still has satanic powers in it, we all are susecptable to illness, at any time; that is not of God’s Kingdom . This was an interesting question and I loved the examples used! it really has me thinking! Thank you. God be with us!

    • LizEst

      Mgwps63 – Please don’t worry about Fr Fortea’s use of the term “if.” He is using “if” for doubtful readers, not because he himself doubts their existence. He has plenty of experience with them.

      All illness is not indirectly caused by the devil. Even original sin was a decision on the part of our first parents, even though they were tempted by the devil. Please reread Fr. Fortea’s first sentence. If God were to permit demons to be either the direct or indirect cause of all illness, this world would be even sicker than it is because of the demonic hatred of humanity.

      • Mary G

        Thanks Liz! after thinking over what you said, I totally realized my wrong thinking! 😧

  • In my grandparents’ house, where I used to live, there are many Chinese antiques; jars, porcelain, buddha figures etc. Looking back, I have no doubt the house is haunted by evil spirits. It would certainly explain some of the problems in their family.

    As a kid I was scared to climb up the stairs alone. I think I might have sensed something but did not know what it was.

    Anyway, I mention this because my Mom told me that she used to these migraines every time she tried to fix or clean things up in their rooms. She suspects that evil spirits have been preventing her from cleaning things up. Maybe they did not want the things in the house rearranged? Is this possible?

  • Sorry going a little off topic, but does Fr. Fortea mention whether demons can attack in our sleep? Like through nightmares?

    • LizEst

      You are ahead of Fr. Fortea! He has a post scheduled on that later this month.

      • Thanks! Looking forward to it!

  • Tessye

    Thank you Father for this post. Within the last 4 weeks, my mother’s normal aches and pains of artritis have suddenly become an acute attack of artritis and birsitus that have prevented her from going to daily mass, weekly confession and sometimes even mass on sunday. Her doctor can’t explain the reason for the sudden change, just old age. And then after the 1st week of my mother’s illness, my brother began to have major problems with his marriage and this has caused more pain to my mother. I truly feel its the evil one attacking my mother who has always been very saintly and prayed over us as children. She tells me her pain is to offer as a sacrafice. Only God knows why this is being allowed, but other then that, she is very healthy.

  • nosidam

    Hi. I have had RA for 35 years. It has slowly progressed. I have been to healing masses for years. I have had a setback or two.
    About a year ago I realized that St. Alphonsus Liguori had severe RA also.
    I pray for his intercession. He I’d my new friend.
    However he went on with his life and had the suffering of RA also. No good meds back then.
    Since Christ wants to heal and cure is it fair to assume that sickness is due to sin and the evil one likes that?
    We are fallen in sin. God does not cause illness, right? Some illness is due to our own choices (like an std maybe) and other illness may just be a product of a fallen world like getting the flu. I do not think we should give the devil too much credit. I believe many factors caused the RA. If I pray for healing and it does not come I guess God wants to use this suffering for redemptive purposes. I guess St. Alphonsus wished for health. But sometimes in those old days some saints preferred suffering. Rather confusing!

    • LizEst

      I didn’t know this about St. Alphonsus. Thanks for that timely information since yesterday was his memorial. Knowing this, I believe he would be a good one to ask for intercession on your behalf for relief from RA.

      The evil one love sin. But, the evil one does not necessary like sickness that one joins to the Lord’s sufferings and is offered for the Lord’s intentions, for expiation of sin, for the promotion of the the Kingdom of God, etc, etc. Suffering joined to Christ has infinite value because of the infinite value of Christ’s actions. So, the reason some saints preferred suffering was not because they liked suffering (otherwise it would not really be suffering) but because they joined this suffering to Christ. In this, they knew God would use the merits of that according to His divine purpose. Remember, Jesus did not have a good time with His passion and death on the cross. He underwent it in order to open the gates of heaven and eternal happiness with Him forever. So great is His love for us!

      If you pray for healing and this does not come, the Lord could use this suffering for redemptive purposes if you join it to Him: for your benefit or for someone else’s benefit, as expiation for your sins, to bring about a greater good, possibly even someone’s conversion. God bless you, nosidam. For your sake, I hope the Lord grants you relief. Keep praying!

  • Oh dear, as usual I come late on this one and I am in hurry and cannot read all your responses but bringing to mind my pre-teen Catechism, my I believe adequate knowledge of my Catholic Faith and Teachings and and what we read in the Surrender to Divine Providence the Devil has absolutely no power to do anything to us. He cannot even influence Nature itself which obeys God as He created it. Nothing can happen to us unless – for His Own Divine Merciful Providence – God allows it. I rest my case

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