In reading the spell Detox (SR4a, page 207), it's quite clear that the Force of the spell must be at least equal to the damage of a toxin (or Power, I suppose, since even not all toxins deal damage). But what about drugs? The spell's description is clear that it works on drugs, but most don't even do damage until they've run their course and then the spell is pointless. In the case of drugs, would the spell at Force 1 really be sufficient to neutralize a drug in a person's body?

Detox doesn't heal damage, but provides relief from symptoms. If you were coming off a nitro bender, it wouldn't cure the 9 points of stun damage, but it would take away the -2 penalty to your limits, and you would feel better. Not every drug does damage, so for some, there is no DV to compare to the spell's Force - for those, I assume any Force would do. Detox is not like antidote or prophylaxis, which affect a drug or toxin currently in your system. It is used afterwards, to negate side affects such as nausea or disorientation.

If we're talking 4a, you might want to check out the chem rules in Arsenal. They aren't perfect, but they do at least mention the issue of drugs not having a listed power for situations where someone wants to resist them.

SR has always had a problem with toxins, drugs and pathogens because they make arbitrary distinctions about which are which (in the case of drugs vs toxins) and how they are treated mechanically. The classic example is Slab, which is classified as a drug but makes a ridiculously effective weapon when used like a toxin.

When I was writing B&B I tried to come up with some rule that would make drugs and toxins work the same for the purpose of resisting effects and how they interact with other systems (like Health spells), but ultimately I couldn't come up with an elegant solution that wouldn't necessitate a total overhaul of those rules (which was beyond the scope of that book).

What's unfortunate is that they chose not to fix SR's drug problem (Ha! Get it?) in the SR5 core rules. Hopefully the Augmentation-equivalent splat book will address it somehow.

So then, assume a Power of 6, unless decided otherwise by the GM. Means then Detox must be cast at Force 7 at least to get the required 1 net hit.