How to left align text in two column itemize

Question

When I use following MWE for getting itemized text in two columns, the item in the list sometimes take a "justified" formatting and thus there is significant space in between two words. This produces a poor looking two column list. How can I make them align to the left, thus improving the look?

\documentclass{article}
   \usepackage{etoolbox}
    \AtBeginEnvironment{itemize}{\begin{multicols}{2}}    %%% this line
    \AtEndEnvironment{itemize}{\end{multicols}}            %%% and this one
    \usepackage{multicol}
    \begin{document}        
    \begin{itemize}
    \item my first item
    \item my second item
    \item my third item in itemized environment
    \item my forth
    \item 5
    \item 6
    \item 7
    \item 8
    \item 9
    \item 10
    \item 11
    \item 12
    \item 13
    \end{itemize}
    \end{document}

Answer 1

You can use \raggedright:

\AtBeginEnvironment{itemize}{\begin{multicols}{2}\raggedright}

\raggedright is local within the multi columns.

Full code:

\documentclass{article}
\usepackage{etoolbox}
\AtBeginEnvironment{itemize}{\begin{multicols}{2}\raggedright}    %%% this line
  \AtEndEnvironment{itemize}{\end{multicols}}            %%% and this one
\usepackage{multicol}
\begin{document}
\begin{itemize}
\item my first item
\item my second item
\item my third item in itemized environment
\item my forth
\item 5
\item 6
\item 7
\item 8
\item 9
\item 10
\item 11
\item 12
\item 13
\end{itemize}
\end{document}

Going one step further, you may put \usepackage{ragged2e} in the preamble and use \RaggedRight instead to get:

\documentclass{article}
\usepackage{ragged2e}
\usepackage{etoolbox}
\AtBeginEnvironment{itemize}{\begin{multicols}{2}\RaggedRight}    %%% this line
  \AtEndEnvironment{itemize}{\end{multicols}}            %%% and this one
\usepackage{multicol}
\begin{document}
\begin{itemize}
\item my first item
\item my second item
\item my third item in itemized environment
\item my forth
\item 5
\item 6
\item 7
\item 8
\item 9
\item 10
\item 11
\item 12
\item 13
\end{itemize}
\end{document}

Main advantage of \RaggedRight is that it allows hyphenation while maintaining ragged rightedness.

Choice is yours.

Answer 2

Don't redefine itemize: you'll lose it and it's better not to.

Just use \raggedright:

\documentclass{article}
\usepackage{multicol}

\newenvironment{twoitemize}
 {\begin{multicols}{2}\raggedright\begin{itemize}}
 {\end{itemize}\end{multicols}}

\begin{document}
\begin{twoitemize}
\item my first item
\item my second item
\item my third item in itemized environment
\item my forth
\item 5
\item 6
\item 7
\item 8
\item 9
\item 10
\item 11
\item 12
\item 13
\end{twoitemize}
\end{document}

Or \RaggedRight from ragged2e as suggested in another answer. But, for your own sake, don't redefine itemize.