Is black seed really a cure for everything in Islam?

What the hadith says

Abu Huraira reported that he heard the Prophet ﷺ say: "There is healing in black cumin for all diseases except death" (Sahih al-Bukhari 5688). A similar version says that Nigella seed is a remedy for every disease except death (Sahih Muslim 2215). The Arabic word translated here as death is as-sam.

Black seeds are small dark seeds used in cooking and traditional remedies across the Middle East, South Asia and North Africa, and sold today as seeds, oil and capsules.

How scholars understand it

• A general statement with a particular meaning. In Arabic, strong, sweeping wording is often used for emphasis. Many scholars say it means black seed has real benefit for many ailments, in the way Allah allows, not that it cures every possible condition.
• A remedy, not the only one. The Prophet ﷺ taught that Allah made a remedy for every disease. He also told people to seek treatment: "Make use of medical treatment, for Allah has not made a disease without appointing a remedy for it, with the exception of one disease, namely old age" (Sunan Abi Dawud 3855). Black seed is one of many such remedies.
• By Allah's permission. Another hadith says a remedy cures "with the permission of Allah" (Sahih Muslim 2204). The healing is from Allah, and black seed is a means.

The Quran says something similar about honey, again without claiming it cures everything:

What about the science?

Researchers have studied black seed, but the evidence for most health claims is still limited. There is no reliable evidence that it cures serious illnesses such as cancer or diabetes. Be careful with online adverts and sellers who promise miracle cures in the name of the sunnah. Using religion to sell a product, or telling a sick person to avoid hospital, is not the sunnah. See Should I get ruqyah or see a doctor for depression?

Using it sensibly

• Think of it as a helper alongside a healthy diet, sleep, exercise and treatment from your doctor.
• Never stop prescribed medicine to try black seed.
• Check with your doctor or pharmacist before taking it as a supplement, especially if you are pregnant, breastfeeding, have a health condition or take other medicines.
• Start small. You can sprinkle the seeds on bread or in salads, or buy a trusted brand of oil.
• Watch your wallet. Beware of very expensive "special" blends.

The same caution applies to vitamins and other supplements. See Can Muslims take protein powder and supplements? Many people also find comfort in charity during illness. See Can giving charity cure illness?