The couple, who share daughters, Sunday Rose, 11, and Faith Margaret, 8, are said to keep their relationship fresh by bonding in the most unusual way.
Nicole and Keith reportedly indulge in his and hers Botox.
A source told top US publication Life & Style that the pair do everything together, allegedly including cosmetic enhancements.
"They’ve gone in for solo treatments, of course, but they also have a cosmetic surgeon who comes to see them in their own home," a source recently alleged to the publication.
According to the insider neither "are opposed to a little filler and a few injections to smooth out some wrinkles".
The source outrageously claims the couple do this "to keep the spark in their relationship alive".
This follows recent claims that Nicole has also worn out her husband with her passionate antics.
"Nicole’s sex drive has shot up like a Roman candle in recent years, and she’s wearing her husband out," an insider outrageously told National Enquirer.