Rachel Uchitel is the newest addition to Celebrity Rehab, and RadarOnline.com has learned Ambien is the drug of choice that landed her there.

We've also learned that she did the drug with Tiger Woods, using it to enhance sex.

In email messages between Uchitel and Woods, obtained exclusively by RadarOnline.com, Tiger asks for Ambien and Rachel says she's worried about being addicted.

• TAGS

• ambien
• Celebrity Addiction
• Celebrity Rehab
• Dr. Drew
• exclusive
• Exclusive Emails
• Janice Dickinson
• Jason Davis
• Jason Wahler
• Jeremy London
• Leif Garrett
• New York
• Prescription Drugs
• Prescription Pills
• Rachel Uchitel
• Shauna Sand
• Tiger Woods
• vh1