Sectumsempra Guide

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Sectumsempra is a curse created by Severus Snape during his time at Hogwarts. He wrote the curse in his Potions book, which he noted belonged to the Half-Blood Prince.

When Harry Potter came into possession of the book, he found the curse, next to which was titled “for enemies” and used it on Draco Malfoy. Snape later used it against George Weasley during the Battle of the Seven Potters, cursing his ear off permanently. 

Sectumsempra Quick Facts

Full Name Sectumsempra 
Type Curse
Hand Movements Slash of the wand
Incantation (sec-TUM-semp-ra)[
Light White
Effect Lacerates the target with multiple slashes
Creator Severus Snape
Last Updated Apr 26, 2022

Sectumsempra Nature

Sectumsempra is a highly dangerous curse. It comes with a wand movement similar to wielding an invisible sword, along with the incantation of the curses name. Doing so slashes the victim from a distance and leaves deep wounds. The wounds are so deep that victims have a high risk of dying from blood loss if treatment is not applied quickly.

Sectumsempra Counters 

The biggest counter-curse to sectumsempra is to deflect it with something like a shield curse. The intended victim can also block it by disarming the person they are fighting before the cursor movements and incantations have been completed.

Sectumsempra must be applied carefully because the curse follows the movements of the wand. So, if a user tries to curse someone but they do not point their wand directly at that person, it can hit an unintended target or miss entirely.

Similarly, this curse does not inflict damage on Inferi, who do not have any blood and cannot react to pain or injuries.

Sectumsempra Treatment

Vulnera Sanentur is the incantation Snape uses to treat it. Any wounds that were inflicted using sectumsempra must be treated with this song-like incantation. The first part of the incantation eases the blood flow, almost like blood clotting.

Once all the blood has been returned cleanly to the body, the incantation knits the wounds together so that more blood loss does not happen. After that, essence of dittany can be applied to the wounds to prevent scarring. 

However, if a body part has been completely severed because of sectumsempra, it cannot grow back. Dark magic reaps permanent impacts, and this is one of them.

Sectumsempra Known Uses


In Harry Potter and the Order of the Phoenix, Harry goes back in time to look at Snape’s worst memory. On the day in question, Harry Potter’s father, James Potter, was bullying Snape after their ordinary Wizarding level exam. Snape directed his wand at James, released a flash of green light, and cut the side of James’ face, splattering his robes with blood.

The fact that this wound was minor, only slashing his face and not his entire body, indicates that a user has more control over the depth of the cut and how many dashes are left on their victim.

In 1997 Draco Malfoy became a Death Eater in retribution for his father failing the dark lord. He was given the task of killing Professor Dumbledore, a task he was supposed to fail to complete. That same year Harry Potter had received a tattered copy of his potions book, on which was written “Property of the Half-Blood Prince.”

Inside Harry found new instructions for many of the options listed in the book, instructions that made the potions easier or more successful. He also found curses and counter curses scribbled in the margins. One of those curses was sectumsempra.

When Harry Potter found Draco Malfoy crying in one of the bathrooms, Draco immediately tried to use a killing curse on him. Harry thought back to the curse he had found in his potions book titled “for enemies,” and he used it.

He did not know the effect it would have. When he used it, it had a significantly more lethal impact than when Snape had used it on James Potter. Draco was immediately slashed all across his chest, his blood flowing into the water on the bathroom floor, and his body fell to the ground. 

Harry Potter was distraught at the repercussions of that particular curse. When Snape stumbled into the bathroom after hearing the noise, he reprimanded Harry for using dark magic and used his abilities to read minds to ascertain where Harry learned such a spell.

When Harry Potter later relayed what had happened to Hermione and Ron, Hermione used the incident as confirmation that whoever wrote the spell in the potions book was a bad person. Meanwhile, Ron countered that not all of the curses were bad, and Harry had used some of them with good results.

When Harry Potter accompanied Professor Dumbledore to find a Horcrux, he tried to use sectumsempra on the army of Inferi. It left slashes across their already dead bodies, but since they were dead and had no blood, it had no impact. 

During the Battle of the Astronomy Tower, after Severus Snape killed Dumbledore, Harry Potter chased Snape and Draco across Hogwarts grounds. Snape deflected every curse Harry Potter threw at him, remarking that Harry would not be allowed to use killing curses.

While Harry Potter did not know it, in this scene, Snape was trying to protect Harry Potter from using an unforgivable curse and wrecking his soul in the process. When other Death Eaters directed curses at Harry Potter, Snape was there to protect Harry, block the curses, and yell at the Death Eaters to leave him in peace.

Harry Potter, overwhelmed with anguish and anger, tried to use sectumsempra, but Snape blocked it, furious at Harry Potter for trying to use one of his spells.

After Harry Potter called him a coward, Professor Snape turned on him, equally burdened with guilt and grief, although Harry Potter didn’t realize this at the time. It was here that Professor Snape admitted that he was the Half-Blood Prince, and he was the one who had invented the curse.

In Harry Potter and the Deathly Hallows, an advance guard showed up to safely transport Harry Potter to the Burrow. They had multiple people disguised as Harry Potter, having used Polyjuice Potion, and they set off as one. Unfortunately, they were attacked by a group of Death Eaters, and Severus Snape was among them.

However, since Severus Snape was technically a double agent acting on orders from the recently deceased Dumbledore, he had to make his attacks look real, but he did his best not to make them lethal. And so, he used sectumsempra against George, cutting off his ear with dark magic instead of killing him.

The slash was meant for Remus Lupin’s back, but he accidentally hit George, leaving him full of guilt. George was never able to regrow the ear but comically referred to himself now as “holey.”

Sectumsempra Trivial and Fun Facts

The name of the curse is comprised of two Latin words: “sectum” which means “to cut,” and “Semper” which means “always.” The spell effectively means to always cut or always sever. It is also a fun pun on the name of the creator, Severus Snape.

The effects of this curse are exactly the same as a severing charm, except it causes more wounds, and you cannot reapply body parts that have been severed.

In the film, when this curse is used, a small white light flashes and makes a cut, but in the books, the light is green.

Professor Lupin recognized it during the Battle of the Seven Potters, which means it was used regularly during their time at Hogwarts. 

Sectumsempra Appearances in Books 

Harry Potter and the Order of the Phoenix

Sectumsempra appears in the following books:

Sectumsempra Appearances in Films

Harry Potter and the Half-Blood Prince

Sectumsempra appears in the following films:

  • Harry Potter and the Half-Blood Prince
  • Harry Potter and the Deathly Hallows: Part 1
  • Harry Potter and the Deathly Hallows: Part 2

Quotes About Sectumsempra 

In Harry Potter and the Half-Blood Prince:

“Blood spurted from Malfoy’s face and chest as though he had been slashed with an invisible sword. He staggered backward and collapsed onto the waterlogged floor with a great splash, his wand falling from his limp right hand. Slipping and staggering, Harry got to his feet and plunged toward Malfoy, whose face was now shining scarlet, his white hands scrabbling at his blood-soaked chest.”

Snape, after catching Harry Potter having used sectumsempra against Draco:

“Apparently I underestimated you, Potter. Who would have thought you knew such Dark Magic? Who taught you that spell?”

Snape admitting he was the Half-Blood Prince and creator of Sectumsempra:

“You dare use my own spells against me, Potter? It was I who invented them — I, the Half-Blood Prince!”


Question: Why did Harry Use Sectumsempra on Malfoy?

Answer: When Harry ran into Malfoy in the bathroom, Malfoy had tried to use an unforgivable curse on him, Malfoy had tried to use Avada Kedavra. Harry used the only curse that he could think of in that moment which happened to be sectumsempra because of his association with enemies and Draco being his biggest enemy.
Later, when Hermione confirms that whoever the Half Blood Prince was, he was no doubt a bad person because of this curse, Ron countered that it was a good thing Harry Potter knew about the curse because otherwise he would be dead.

Question: How did Snape Create Sectumsempra?

It is not known specifically how Snape created sectumsempra. However, Professor Lupin explained once that different curses go in and out of style just like clothing or music trends so some of them were invented hundreds of years ago but are being brought back while others are brand new.
However Snape created it, it is likely the exact same way that every curse in the magical world has ever been created.

Question: Is Sectumsempra a Killing Curse?

Sectumsempra is not technically a killing curse. Avada Kedavra instantly kills the victim and there is no counter-curse or way to revive someone after they have been killed. Sectumsempra is more of an assault curse.
If it were more widely known it might very well be illegal but it was made up by Severus Snape which meant it hadn’t been around for a long time and he didn’t widely publish it.


Research Citations:

  • Rowling, J. K. Harry Potter and the Order of the Phoenix. New York: Listening Library, 2003.
  • Rowling, J. K. (2010). Harry Potter and the Half-Blood Prince. London: Bloomsbury. Chicago (Author-Date, 15th ed.) Rowling, J. K. 2010.
  • Rowling, J.K. Harry Potter and the Deathly Hallows. New York: Arthur A. Levine Books, 2007.

Continue reading:

Amortentia Guide

Apparate Guide

Avada Kedavra Spell Guide

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