Table 4. Theme 3.

Disease-specific substance use knowledge.

Subtheme	Concept	Exemplar quote
Information deficits	Questions and gaps in knowledge	I've always been told that [drinking] messes everything up but I don't know if [my blood sugar] goes high or low. (17-year-old male with T1D) …ultimately, how [does drinking] really affect Crohn’s? Because even though you see it online that this is what happens, you don’t know the actual bodily process of why that happens. (19-year-old female with IBD)
	Obtaining information on one’s own	I read–before–my bottles of medicine. It's like, "Do not take with alcohol." And I just went online, [to check] if it's good to drink alcohol with medicine, and basically it just said like, "No, don't [drink] because [the medicine] won't work." (16-year-old female with polymyositis) I Googled if there were any super adverse side effects [of drinking]…just to make sure there were no, "you're gonna die if you do this" or anything like that. (19-year-old female with IBD) [My pediatrician] said something about [how] my medication is absorbed through my liver…[and how drinking] can mess up the absorption of my medication…it made me a bit worried but when I asked my older friends, they said that if it’s once in a while…it’s probably not going to do anything. (18-year-old female with JIA).
Preferences for content and delivery of substance use messages	Factual and disease-specific	…[what] made an impression on me is probably the fact that the glucagon wouldn't work if I was severely intoxicated…I think that's the thing that I'd really say scared me the most because that's kind of a scary thought that like, you could die from drinking because your blood sugar was low and they had no way–and even in the hospital, they can give you IV's and stuff, but they really can't do much for you until the alcohol has been processed through your system. (18-year-old female with T1D) [The topic of drinking] should be integrated when [providers] talk to you about how exercise and stress and things like that may affect your blood sugar. They should include alcohol and say what it does…that way the patient will know if they do make the decision to drink. Then they know what happens to their blood sugar levels and they know it's affecting them rather than having them drink and then having something bad happen and they'll have to learn from their mistakes instead of knowing from the beginning. (17-year-old male with T1D)
	From the specialist	…there is no other person in my life or anyone's life that has Crohn’s or any disease that knows more about, not only the disease, but my experience with the disease than my [GI] doctor. He is the utmost figure of knowledge, so I always want to hear what my doctor has to say. (19-year-old female with IBD) Your diabetes doctor should know the most about the positive and negative side effects about [using substances with] diabetes…they should know the most and should have the most advice to give–the most solid advice to give–as opposed to like looking it up on the Internet … (19-year-old male with T1D) I would definitely look to [my gastroenterologist] for someone to give advice on how much [alcohol] I should be consuming because he knows best about how it would affect my body. (19-year-old female with IBD).
	Direct and honest	…laying out all of the information [about drugs and alcohol] is probably the best thing to do…not trying to hold back any information because it might be scary. I think it's just best to say everything, even if it's unlikely to occur…it's best to be the most informed about any situation that could occur. (19-year-old female with IBD-associated arthritis) I mean sometimes because we're underage, pediatricians and children's doctors just kind of sugarcoat it kind of thing, and I'd rather someone just tells me exactly what's happening. (19-year-old female with JIA)
	Perceived permission	[My endocrinologist] says, ‘Stay away from rum. Scotch and whiskey are okay.’ …I definitely try to follow that rule. (18-year-old male with T1D). I mean [my doctor] realizes every 17-year-old is going to drink–it's just kind of bound to happen. (17-year-old male with T1D)
	Humanize the message	I feel like stories or like examples from your life or someone you know is kind of a good thing to tell people because then you know it’s real, like it actually happens. (16-year-old female with JIA) …because my doctor has diabetes, she's not just telling stuff she read in a book somewhere; she's telling me her personal stories…It means more when it's personal. (19-year-old male with T1D)
	Sensitive to developmental context and social pressures	I know doctors usually aren't our age but I feel like it'd be much more helpful to try to get on the level that like teens are at…most doctors now don't really know what kind of peer pressure is out there and stuff like that so I feel like it'd be more helpful to be like, "Well, I know the situation you're in and I know that you're being pressured to do these things and whatnot but you really have to not do that." (19-year-old female with IBD-associated arthritis)
	Private and confidential	…the problem is, though, that especially in [specialty care for] pediatrics, most of the time the kid’s parent is in [the clinic room] …I wish that a doctor could ask a parent to step out for a minute or something and be like, "Is there anything else you want to talk to me about?" That way a kid can feel safe. (19-year-old female with IBD) I mean no offense to [my rheumatologist], but I felt like he should have kind of like knew not to ask [about marijuana use] in front of a parent if he wanted a truthful answer. (16-year-old female with JIA)