[Da_Noob]

You're KillUseDrugs public function isn't needed.
It should look something like this:

pawn Код:

CMD:givemedrugs(playerid, params[])
{
    SendClientMessage(playerid, -1,"You have received 1 drugs");
    PlayerInfo[playerid][pHasDrugs]++;
    return 1;
}
CMD:takedrugs(playerid, params[])
{
    if(PlayerInfo[playerid][pHasDrugs] >= 1)
    {
        UseDrugs1[playerid] = SetTimerEx("UseDrugs", 1000, true, "i", playerid);
    }
    else if(PlayerInfo[playerid][pHasDrugs] >= 0)
    {
        SendClientMessage(playerid, COL_RED,"You do not have any drugs.");
    }
    return 1;
}

forward UseDrugs(playerid);
public UseDrugs(playerid)
{
    KillTimer(UseDrugs1[playerid]);
    new float:health, float:newhealth;
    GetPlayerHealth(playerid,health);
    newhealth = health + 5;
    SetPlayerHealth(playerid, newhealth);
    return 1;
}

Try this, this will add 5 HP to the person's HP level.