Source: The Great Interpretation of Dreams (Ibn Sirin)
Thorns in a dream indicate evil, difficult men, or strife, debt, and worry. Them entering the body indicates falling into strife or debt.
Source: Perfuming Humanity in the Expression of Dreams (Al-Nabulsi)
Thorns indicate harm, worry, and grief. Removing them indicates the end of worry.
Source: Signs in the Science of Expressions (Ibn Shaheen)
Thorns are interpreted as worry. Whoever sees them pricking him will be afflicted with worry.