Don’t be offended by the 4-star words out of his mouth.

Here’s the opening to “I Swear.” Everyone is getting ready to see the Queen of England award John Davidson, who has Tourette Syndrome. He says he doesn’t want to be there, and here’s what he accidentally says: “F the Queen!.”

Then the movie flashes back to the 80s, when he started to develop the condition. He begins twitching, having a stiff neck, and cursing when he doesn’t want to. It was common at the time for people to not completely understand Tourettes and think he’s faking it. He gets his hand whipped by the headmaster (Ron Donachie) for cursing, his parents (Shirley Henderson and Steven Cree) make him eat on the floor in front of their fireplace for accidentally spitting at the table, and he’s getting into fights at school. That’s why he gets expelled from his school, and that’s why his father calls it quits.

As he gets older and played by Robert Armayo, the only people that could tolerate his condition are his friend Murray’s (Francesco Piancentini-Smith) family-particularly his mental health nurse mother Dottie (Maxine Peake from “The Theory of Everything”). She tells them the one rule in their house: “If you do anything you can’t help, you don’t have to apologize for it.” Indicating, that she becomes the better mother than his own at this point, and she’s willing to help him see his condition through.

“I Swear” is the first biopic from director Kirk Jones, whose credits include “Waking Ned Devine,” “Nanny McPhee,” and “My Big Fat Greek Wedding,” and he commits to the real life activist and his reality. How would a person respond to a person cursing uncontrollably back then? Did they believe the person or think they were faking their condition? I always wonder the same thing about how autism was examined back in the day, but that’s a different story.

As John gets older, complications and celebrations emerge. It goes from bad to good. I’ll start with the bad news.

The bad news. He accidentally calls a woman a “slut,” and gets beaten up by two guys for it. He struggles to solemnly swear to tell the whole truth and nothing but the truth in court. And when a guy asks him to help sell drugs and he doesn’t, his condition forces him say he’s dealing drugs to the police.

Now, the good news. He gets land a job at a local community center with the aging caretaker Tommy Trotter (Peter Mullan), and the rest of the movie shows how he himself transitions into an activist helping those with Tourette’s and make more people aware of the condition.

The corporal punishment scenes are too overbearing for me, but I suppose the movie is supposed to authentic in these cases. I swear to you “I Swear” is a riveting and powerful acted film regarding Tourette’s and how to take care of it. Aramayo gives a career best performance in the ways he adapts to the real life character. Every time he says “HEY!,” we’re either shocked or we think he’s trying to get someone’s attention, but he’s not. Every time he moves his hands and apologizes for cursing to people who don’t know about his condition, we hope somebody can be understanding. These are different times, and the movie allows the present day to help show us the high spirits. And the supporting performances from Peake, Henderson, and Mullan are profoundly excellent, as they respectively deliver dialogue resonating with the young man’s reality.

Now take “Coffee & Kareem,” a terrible Netflix comedy about a foul-mouthed boy, and compare that movie to “I Swear.” That movie made the fatal mistake of assuming that cursing too much is supposed to be hilarious beyond the point of no return. This one, however, is supposed to curse to represent Tourette’s and how people respond to it. Sometimes, it can be funny, other times, it can be sincere, and all the time, it’s a strong dramatization.