Justine Rivero considers herself a bonafide personal-finance expert. She’s an adviser at the credit-tracking website Credit Karma, doling out tips on how to control spending, avoid crippling debt and keep your credit record pristine.

But even Justine Rivero is powerless against the lure of popular daily-deal site Groupon. When faced with a seemingly incredible bargain, she finds herself compelled to click that mouse again and again – against her own better judgment.

“I regretfully admit to totally blowing money on Groupons I never used,” says Rivero. “A dinner cruise for six people, a paintballing weekend, yoga classes. I swore it off for awhile, until something else popped up that I couldn’t resist. I should know better.”

Rivero isn’t alone in her hopeless addiction to the site. Think of it as a new strain of the virus that has long bedeviled shoppers at big-box retailers like Costco, Walmart or Target: The compulsion to buy a five-gallon jar of capers, or a gross of electric toothbrushes, because the deal is just too good to pass up. As a result, you end up spending far more than you would have otherwise.

“When we see that ticking clock stating there are only 45 minutes left until the offer expires, we lose our minds,” says Farnoosh Torabi, a personal-finance expert and author of the books Psych Yourself Rich and You’re So Money. “Our dopamine levels skyrocket, and we begin to imagine taking that balloon ride for 50 percent off or enjoying those buy-one-get-one-free smoothies. We end up making an impulse purchase -- only to regret it soon after.”