Dax Shepard and Kristen Bell. Picture: Bang Showbiz

Dax Shepard has jumped to his wife Kristen Bell's defence and told their critics to "get real" after she was slammed for smoking marijuana around him. 

The 'Frozen' actress admitted earlier this week that she occasionally has a few puffs of weed to help her relax after a long week at work, but her honesty appalled some people as they hit out at her for teasing her sober husband. 

Taking to Twitter after he was bombarded with messages, Dax - who battled with substance abuse since the age of 18 but has been sober for 14 years - fumed: "That would be like a diabetic expecting their partner to never eat dessert. Get real!"

One fan responded and admitted that he used to be a cocaine addict and if someone were to "do lines" in front of him he would have to "think about that."

To which the 43-year-old actor replied: "Yeah, she could most definitely NOT do lines in front of me (sic)."

Dax then went on to say that it would be a "different" story if she was drinking in front of him because boozing is "a lot more dangerous" than smoking marijuana. 

He explained: "Well it's different in that drinking is much more dangerous."

Kristen - who has two daughters Lincoln, five, and Delta, three, with Dax - found herself in the firing line this week when she said she smokes around her husband.

She said: "I smoke around my husband and it doesn't seem to bother him."

When asked how many times she lights up, she replied: "Once a week, if I am exhausted and we are about to sit down and watch 60 Minutes, why not?"

The 38-year-old star then went on to say that Dax has even tried to encourage to her dabble in harder drugs like ecstasy because everyone should "experience it."

She said her husband believes "you shouldn't leave earth without having tried mushrooms or ecstasy." 

And, despite his past, he understands that "he lost his privilege with them [drugs] because he can't handle it; his brain doesn't have the chemistry to handle it."