Ok, the top question I do not see the milligram of
gabapentin. 800 mg three times a day is the usual top dose.
However, a key point on medications is the dose dependence of bad things happening. The relationship between drug and bad things varies all over the place.
Gabapentin is extremely LOW RISK, HIGH SAFETY, but, it's side effect curve (sleepiness) is weird in that it starts at about 1 in three people at the low dose having sleepiness and it doesn't really change much with higher
dosing. Bad stuff doesn't seem to happen with much higher doses as opposed to most things (like water) where going up 3 to 5 fold is dangerous.
Flexeril is dangerous above the recommended dose which is the MAXIMUM SAFE DOSE. It affects muscle including heart. Bad.
Narcotics are the more usual case. low low doses don't do much. Average doses have some risks and some help. Going above the recommended dose increases both some pain relief but vastly increases the danger of stopping breathing, addiction, etc.
Can't say about the back injections because I do not know what is injected.
Steroids would typically stick in any space they are put into for weeks not days, but this depends on if it is steroids injected and what type of steroid.
Lidocaine wouldn't last as long but it's quite safe except for the needle which can hit something each time. Steroids in theory weaken muscle, tendon, bone, but I've never seen anyone who's gotten 10 injections in their entire lives so, I cannot comment on actual problems. The near 100% risk of local minor bruising and local pain and significant risk of spinal fluid leak with spinal injections are the biggest risk (of minor seriousness). Back muscle injections....the injections themselves are really close to zero risk; we do antibiotic shots daily. Thousands. Not much risk. Oh wait flu shots.
tens of thousands. Not much risk.