Can lactulose go bad and if so how can you tell (other than the expiry date) like taste, color etc?

Yes, I have a bunch of expired bottles of this. I have SOOOO MANY, because I don’t need to take it very often, it was cheap, and my husband just kept picking it up rather than me telling him not to fill it. Anyway, I want to also say I’ve ALWAYS stored them in our dark hallway closet. The house has a heater in winter, AC in summer, so it stays around 66-68 degrees.
I also try to open one that still has the silver on it, (sealed top) so that makes me feel better. But I only take a sip and it works within an hour. I likely wouldn’t take a large dose at once, so I can’t attest to more than a swig.
I have never looked to see if it’s dark in color either! I’ll stop rambling btw- last thing to add is they’re two years past their expiration date. I hope this helps! Take care everyone, and stay safe!

Can you still take lactulose 10gm/15 ml solution after the expiration date on the bottle and will it still be as good

What will happen to me if i take out of date lactulose?

Per https://www.drugs.com/pro/lactulose.html, which is said to be from the FDA:

"Under recommended storage conditions, a normal darkening of color may occur. Such darkening is characteristic of sugar solutions and does not affect therapeutic action. Prolonged exposure to temperatures above 86°F (30°C) or to direct light may cause extreme darkening and turbidity which may be pharmaceutically objectionable. If this condition develops, do not use."