There is no one answer to this question as it depends on your playing style and the specific rules of blackjack. However, in general, it is generally safe to say that you can only lose 10 hands of blackjack in a row.
If you are playing with basic rules, such as betting on each hand, then it is very unlikely that you will lose more than 10 hands in a row. If, however, you are playing with some variation of rules that allow you to wager more money on specific hands (such as surrendering hands), then it is possible to lose more than 10 hands in a row.
Ultimately, the safest bet is always to play conservatively and avoid risking too much money on any one hand. If you do end up losing more than 10 hands in a row, then there is always the option to withdraw from the game and try again later.
