I've got out of the habit, but, when I was riding in less urban/more bleak areas (and on roughstuff fairly often), I carried the basics.
I know people think that BLS and First Aid is a bit over the top, but, let me tell you - some sound training and a dressing or a bandage can patch someone up well enough not to make things worse before professional help can get to you/you to it.
A couple of basic dressings can often be the difference between carrying on to finish a ride and bailing completely.
These days, beyond my pills & inhalers*, I carry a mask and gloves and have recent BLS training. Probably all that's needed on an hour's riding on urban streets a few short minutes away from ambulances and casualty units, but, if it comes to it, I will 'Nelly the Elephant' someone till the Paramedics get there. Any loss of circulation can do immense damage. Fortunately, in the incident I witnessed, the injured person was conscious. But I wouldn't guarantee it every time.
* I carry Ventolin (and, often, a spare), paracetomol, Ibuprofen at the moment (but not normally), Gaviscon, and usually antihistamines in summer. Overnight, I take oral steroids, and two more inhalers. I've finally managed to go away without my nebuliser
Oh - and I have witchhazel stick for any sores, as well as Minty Arse Lard for prophylaxis of same.