Heroin, as with other opiates, causes rapid tolerance when used frequently, so doses increase dramatically from first dose in a month to 20th dose in a month. There has been some debate about how much heroin doses actually increase with tolerance.

Howard Lotsof, a renowned researcher into ibogaine treatment of heroin addiction, has estimated that a "low end analgesic dose of heroin would be about 1 mg." Most users start with doses much higher than this. Insufflated doses of heroin probably start at between 5 and 20 mg of pure heroin and intravenous doses probably start between 5 and 10 mg.

As usage increases, however, the doses get much higher. Dr Lotsof wrote "In close to twenty years of research and involvement with the treatment of opioid dependence with ibogaine the highest dose I personally saw used of heroin in Europe was 2 grams [per day], that is 2,000 mgs." 2 grams per day, however, is extremely high, much higher than most heroin addicts achieve. Heroin is very expensive and this dosage level would be fatal in most people who had not worked up their dosages slowly.

In the book "The science and love of Alcohol and Caffeine" by Stephen Braun (1996), he writes:

"Longtime heroin users, for instance, have been observed to require ten thousand times the dose they injected when they began their habit. Their brains adapt to heroin to such an extent that they inject themselves with quantities of this narcotic that could kill a person not tolerant to heroin." (Page 168)

Braun gives "Goldstein, A. 'Addiction, from Biology to Drug Policy.' New York: Freeman." as his source for this information, but this "10,000 times" increase in dose appears to be exaggerated.

When the Swiss government began allowing maintanence of heroin users, they were able to collect reliable data about exactly how much heroin was being used. The Swiss found that users offered unlimited quantities would, on average, max out at between 300 and 500 mg. of diacetylmorphine per day. One author writes "I've known people prescribed a full gram per day, but they were quite unusual, and such habits on the street are impossible except for relatively high level dealers. Remember, I'm talking about pure pharmaceutical or number 4 if on the street. There are certainly cases of pain patients receiving larger equivalent dosages of opioids, but I've never heard of one of these beating a 1000/1 ratio."

The Swiss data was published in 1999:

Prescription of Narcotics for Heroin Addicts: Main Results of the Swiss National Cohort Study
Volume One. Uchtenhagen, A;Dobler-Mikola, A.; Steffen, T; Gutzwiller, F.; Blattler, R; Pfeifer, S. Karger; Basel; 1999

Page 20 states that the mean daily dose of heroin IV ( when used alone, without methadone on the side) was 491.7 mg.

Page 22 states "A stable dose was achieved after 6 months at most; beyond this point, almost no further increases in dose were required."

Later in the volume, the authors state that most users tend to gradually reduce their dosages after achieving a peak.

This Swiss data is the best currently available about maximum daily heroin dosages when humans are given nearly unlimited access to the chemical. Using their data, it appears the actual ratio between initial doses of heroin, a low of 5 mg per dose, and highly-tolerant maximum daily doses of heroin of about 500 mg, this is a 1 to 100 ratio. But it also ignores the difference between single-dose use and repeated dose use. In the same way that it's easy to finish off several bottles of wine over the course of several hours, while few ever drink several bottles of wine in just a few minutes, heroin users who are using throughout the day will go through a lot more heroin. So its inappropriate to compare single-dose initial values to daily-ingestion amounts. The increase between no-tolerance dosages and high-tolerance dosages is thus much less than 1 to 100.