Sefer Ha’mitzvos Ha’Katzar (The concise book of mitzvos) By the Chofetz Chaim
This book lists the Torah mitzvos that can be observed today
Second Section – the Negative Commandments
45. It is a negative commandment “Do not curse a proper Jewish person”
As it states in Vayikra (Leviticus) 19:14, “do not curse a deaf person.” When it speaks of a deaf person, it means to include others because this is true for a person who does not hear and is not hurt when he is cursed, but a person still transgresses this negative commandment if he curses him. If a person curses himself, he has also transgressed this negative commandment. A person does not transgress this commandment unless he curses using the name of G-d or one of His characteristics. If the curse was made using a name that used for G-d in another language, this counts as one of His characteristics.
This applies in all places and at all times, for men and for women.
4. Be kind to yourself. Speaking badly even about yourself is unethical.
הלכות שמירת הלשון 