In Islamic law, consuming flowing blood is prohibited, while meat itself is permissible once the animal has been properly slaughtered according to Sharīʿah. Allah تعالى says: “Forbidden to you are carrion, blood, the flesh of swine…” This prohibition refers specifically to blood that flows, not what remains naturally within the meat after slaughter.

The red liquid seen in rare or medium-cooked steak is not flowing blood. It is scientifically established—and acknowledged by contemporary scholars—that this substance is primarily myoglobin, a protein found in muscle tissue, mixed with water. During proper slaughter, the blood is drained from the animal, but trace proteins and fluids remain in the meat itself. These residual fluids are not classified as blood in the Sharʿi sense.

Classical jurists addressed similar concerns and clarified that what remains in the veins, flesh, and organs after slaughter is excused and does not render the meat impermissible. The meat of animals slaughtered lawfully was eaten by the Companions without requiring it to be overcooked or completely dry.

Therefore, eating steak that is rare or medium is halal, provided the animal was slaughtered correctly according to Islamic requirements. The presence of red juices does not make the meat haram, as this is not flowing blood.

However, separate from permissibility, personal preference and health considerations may be taken into account. If someone avoids undercooked meat due to health concerns, that is a personal or medical choice, not a religious obligation.

Summary ruling:
Eating steak that is not well done is halal, as the red liquid is not blood but myoglobin and water, provided the meat comes from a properly slaughtered halal animal.