Short answer
It depends on why and how. Steroids or testosterone prescribed by a doctor for a real medical condition are allowed. Taking anabolic steroids without medical need to build muscle, at doses that harm the body, is not allowed in the Hanafi school, because Islam forbids harming yourself. Using them to cheat in sport adds the sin of deception.
Medicines are judged by their effect. Prescribed steroids (such as corticosteroids, or testosterone for a diagnosed deficiency) are permissible treatment. Anabolic steroids used without need, where they cause real harm, are impermissible because of the harm, and using them to deceive in competition is haram.
The four schools agree on this.
Explanation
"Steroids" covers very different things. Corticosteroids, such as prednisolone, inhalers for asthma and creams for eczema, are everyday medicines. Testosterone replacement therapy (TRT) treats a diagnosed hormone deficiency. Anabolic steroids, taken in large doses to build muscle, are what most people mean when they ask this question.
Medical use is allowed. The Prophet ﷺ told people to seek treatment, because Allah has sent down a cure for every disease. A steroid or hormone that a qualified doctor prescribes for a real condition, at the dose they set, is treatment like any other medicine.
Use without need is the problem. Islam teaches that your body is a trust and has a right over you, and the Quran says not to throw yourselves into destruction with your own hands. Anabolic steroids taken without medical supervision are linked to serious harms, including heart disease, liver damage, infertility, mood changes and dependency. On that basis Hanafi muftis treat cycles for size or looks as impermissible. Wanting to be strong is good; the Prophet ﷺ praised the strong believer. The way there is training, food and rest.
Sport adds deception. Where steroids are banned, using them to compete is cheating, and the Prophet ﷺ said whoever deceives us is not one of us. Prizes won that way are not rightly earned.
If you are already using them, do not stop suddenly without advice, since coming off can itself be harmful. Speak to a doctor, follow a qualified doctor's plan, and ask a mufti about your own situation. Selling anabolic steroids for misuse is also not allowed, as it helps others harm themselves.
Ask a mufti about your own case. This answer explains the general ruling. When the details of your situation matter, as they do here, ask a qualified mufti and give them the full facts. Where to ask a scholar.
The evidence
Quran, Surah Al-Baqara 2:195
وَأَنفِقُوا۟ فِى سَبِيلِ ٱللَّهِ وَلَا تُلْقُوا۟ بِأَيْدِيكُمْ إِلَى ٱلتَّهْلُكَةِ ۛ وَأَحْسِنُوٓا۟ ۛ إِنَّ ٱللَّهَ يُحِبُّ ٱلْمُحْسِنِينَ ﴿١٩٥﴾
And spend in the way of Allah and do not throw [yourselves] with your [own] hands into destruction [by refraining]. And do good; indeed, Allah loves the doers of good.
Knowingly harming your own body is forbidden.
Quran, Surah An-Nisaa 4:29
يَٰٓأَيُّهَا ٱلَّذِينَ ءَامَنُوا۟ لَا تَأْكُلُوٓا۟ أَمْوَٰلَكُم بَيْنَكُم بِٱلْبَٰطِلِ إِلَّآ أَن تَكُونَ تِجَٰرَةً عَن تَرَاضٍۢ مِّنكُمْ ۚ وَلَا تَقْتُلُوٓا۟ أَنفُسَكُمْ ۚ إِنَّ ٱللَّهَ كَانَ بِكُمْ رَحِيمًۭا ﴿٢٩﴾
O you who have believed, do not consume one another's wealth unjustly but only [in lawful] business by mutual consent. And do not kill yourselves [or one another]. Indeed, Allah is to you ever Merciful.
Your life and health are protected, even from yourself.
Sahih al-Bukhari 1975
Sahih... فإن لجسدك عليك حقا ...
"Your body has a right over you."
Looking after the body is a duty, not a matter of taste.
Sahih Muslim 101
Sahih... من غشنا فليس منا ...
"Whoever deceives us is not one of us."
Using banned substances to win is deception.
Sahih Muslim 2664
Sahih... المؤمن القوي خير وأحب إلى الله من المؤمن الضعيف ...
"The strong believer is better and more beloved to Allah than the weak believer."
Strength is praised, but it must be sought by lawful means.
Where the ruling is recorded
- al-Fatawa al-Hindiyya, Kitab al-Karahiyya, chapter on treatment. Treatment with medicines is permitted when it benefits and does not cause greater harm.
- Radd al-Muhtar (Ibn Abidin), Kitab al-Hazr wa al-Ibaha. What harms the body is forbidden to consume.
Checked by our team. For a more accurate answer to your own situation, consult a scholar. Quran translation by Sahih International. Hadith Arabic from the standard editions of the six books and the Muwatta, with gradings as recorded there; the English is our own rendering. Spotted a mistake? Tell us.