There are no official guidelines to assist in answering this question. I will search for relevant research papers instead.
From the FDA Drug Label
DRUG ABUSE AND DEPENDENCE Controlled Substance Diphenoxylate hydrochloride and atropine sulfate tablets are classified as a Schedule V controlled substance. Diphenoxylate hydrochloride is chemically related to the narcotic analgesic meperidine. Drug Abuse and Dependence In doses used for the treatment of diarrhea, whether acute or chronic, diphenoxylate has not produced addiction Diphenoxylate hydrochloride is devoid of morphine-like subjective effects at therapeutic doses. At high doses it exhibits codeine-like subjective effects. The dose which produces antidiarrheal action is widely separated from the dose which causes central nervous system effects The insolubility of diphenoxylate hydrochloride in commonly available aqueous media precludes intravenous self-administration. A dose of 100 to 300 mg/day, which is equivalent to 40 to 120 tablets, administered to humans for 40 to 70 days, produced opiate withdrawal symptoms. Since addiction to diphenoxylate hydrochloride is possible at high doses, the recommended dosage should not be exceeded.
Addiction potential: Lomotil (diphenoxylate) has the potential to be addictive, but only at high doses.
- At therapeutic doses, diphenoxylate has not produced addiction.
- High doses (100 to 300 mg/day) can produce opiate withdrawal symptoms and have the potential for addiction 1.
From the Research
Addictive Properties of Lomotil (Diphenoxylate)
- Lomotil (diphenoxylate) has been reported to have a potential for abuse due to the presence of opioid 2.
- A study found that 41 patients presented with dependence on Lomotil as the primary substance of abuse, with most patients being married and employed males, educated up to 10th grade, and belonging to a rural Sikh extended or joint family 2.
- The reasons for initiation of diphenoxylate use included relieving withdrawals, using it as a cheap substitute opioid, curiosity, and suggestion of friends 2.
Regulatory Controls and Misuse
- Regulatory controls are needed to prevent escalation of use of this easily available prescription opioid 2.
- Lomotil is a medication with a potential for abuse, and its misuse can lead to serious toxicity, especially in children [(3,4)].
Toxicity and Treatment
- Diphenoxylate-atropine (Lomotil) intoxication can cause somnolence, flushness, and respiratory depression, and can be treated with naloxone [(3,5,6,4)].
- Early treatment with naloxone can reverse the symptoms of Lomotil toxicity [(5,6)].
- Accidental ingestion of Lomotil is a common cause of toxicity in children, and prompt treatment is essential to prevent serious complications [(3,6,4)].