Mexico Drug Possession Laws: Thresholds, Penalties & Foreigner Risks

Mexico drug possession laws set very small personal-use thresholds — 5 grams of cannabis, 500 milligrams of cocaine, 50 milligrams of heroin, and smaller amounts for other substances — and anything above those limits is a criminal offense carrying ten months to eight years in prison. Stay at or below the threshold and the first two times you’re stopped should end with no charge. Go over by any margin and the personal-use protection disappears completely. For foreign visitors, a conviction almost always brings deportation and a re-entry ban on top of the criminal sentence.

The Personal-Use Thresholds That Decide Everything

Article 479 of Mexico’s General Health Law lists the maximum amount of each substance that qualifies as “strictly for immediate personal consumption”:

Cannabis: 5 grams
Cocaine: 500 milligrams
Heroin: 50 milligrams
Methamphetamine: 40 milligrams (in a single unit weighing no more than 200 milligrams)
MDMA (ecstasy): 40 milligrams (one unit)
LSD: 0.015 milligrams

These numbers are absolute. Authorities weigh the substance as-is, with no adjustment for purity or cutting agents, so a bag of cocaine that’s mostly filler still counts at its full weight. One milligram over the line and the personal-use protection is gone.¹

The methamphetamine figure trips people up. The threshold is 40 milligrams of the drug itself; the 200-milligram number in the same provision is only the maximum weight of a single unit (a pill or crystal) that can carry that 40 milligrams. Online summaries sometimes report the limit as 200 milligrams, and that is wrong.

What Happens If You’re At or Below the Limit

If police find you with a quantity at or below the Article 479 thresholds, the law says you should not be charged. Under Article 478, the officer records the stop with a notation of “no penal action” and releases you. That record starts a count. The first and second time you’re stopped at personal-use amounts, you’re released and encouraged to seek treatment voluntarily. The third time, treatment becomes mandatory.¹

That is how the statute reads. How it plays out on the street can look different. Officers across Mexico’s 32 states apply the rules inconsistently, and foreign visitors in particular report being pressured for bribes regardless of quantity. Knowing the law gives you ground to stand on if the encounter escalates to a prosecutor, but it does not guarantee the roadside stop ends the way the statute says it should.

A separate note on cannabis: Mexico’s Supreme Court declared the blanket prohibition on recreational use unconstitutional in 2021 and ordered Congress to legalize. Congress has missed every deadline, and no comprehensive cannabis law exists as of early 2025.² COFEPRIS can issue individual permits allowing adults to grow and consume cannabis at home, but the official application requires a Mexican voter credential, and results for non-citizens are inconsistent. For practical purposes, the 5-gram threshold is still the operative limit.

Penalties If You Go Over the Threshold

Once your quantity exceeds the Article 479 threshold but stays below one thousand times that amount, you’re in the narcomenudeo (small-scale dealing) zone. The penalties scale with what prosecutors think you were doing with the drugs.

Simple possession (Article 477): ten months to three years in prison, plus a fine of up to 80 days’ UMA. The UMA is Mexico’s standard reference unit for fines; the 2026 daily UMA is roughly 117 pesos,³ so the maximum fine lands near 9,400 pesos. First-time offenders tend to see sentences closer to the ten-month floor.

Possession with intent to sell or supply (Article 476): three to six years in prison and 80 to 300 days’ fine. Prosecutors don’t need to catch you in a transaction. They build these cases on circumstantial signals: precision scales, drugs divided into individual baggies, cash in small denominations, multiple phones, a ledger. Even modest total weight can push a case from Article 477 into Article 476, tripling the minimum sentence.

Actually selling or supplying (Article 475): four to eight years in prison and 200 to 400 days’ fine. This covers completed transactions, and the statute explicitly includes giving drugs away for free.¹

The gap between simple possession and the intent-to-sell charge is where most defense work happens, because it’s the difference between a short sentence (often negotiable) and real prison time.

When the Case Becomes Federal

Narcomenudeo covers quantities below one thousand times the Article 479 thresholds. In concrete terms, that ceiling is 5,000 grams for cannabis (about 11 pounds) and 500 grams for cocaine. Hit those levels, or show any connection to organized crime, and Article 474 kicks the case to federal prosecutors.¹ Federal cases are prosecuted under the Federal Penal Code with substantially longer sentences, and the practical experience of federal detention is harsher: longer proceedings, harder access to family and counsel, and often placement far from where you were arrested.

Mandatory Pretrial Detention for Drug Charges

This is where the stakes change. Article 19 of the Mexican Constitution lists offenses that trigger automatic pretrial detention, and a 2019 constitutional reform added “crimes against health” to that list. For charges above simple possession, a judge has no discretion to release you while your case is pending. You sit in a Mexican jail for the duration of the proceedings, which can run months or longer. The reform has been criticized by the UN High Commissioner for Human Rights and legal observers for removing individualized detention assessments, but it is in force.

Before charges are filed, the Ministerio Público (Public Prosecutor) has 48 hours after your detention to classify you as a consumer, a dependent user, or a criminal defendant, and to decide whether to charge you.⁴ That window is a constitutional safeguard, but bureaucratic delays sometimes stretch it in practice.

Prescription Medications That Can Trigger an Arrest

This catches more travelers than the recreational-drug rules do. Several medications sold over the counter or by prescription in the United States are banned outright in Mexico. Products containing pseudoephedrine (Sudafed, Actifed, Vicks inhalers) and codeine are prohibited, and bringing them across the border is a criminal offense rather than an administrative fine.⁵

Adderall is a particular hazard. Amphetamines are tightly controlled, and Adderall as a brand is not approved for sale in Mexico. If you take ADHD medication, check COFEPRIS’s controlled-substance lists (Lista Amarilla, Lista Verde, Lista Roja) before you travel.

For medications that are controlled but not banned, you can bring a personal supply in with documentation. You need a prescription or doctor’s letter listing the medication name, daily dosage, trip quantity, and the prescribing doctor’s name, signature, phone number, address, and professional license number. Have it translated into Spanish. Keep the medication in its original pharmacy container; pill organizers and unlabeled bags are a problem. Bring only enough for the trip, and declare controlled medications to customs on entry.⁵ The CDC also recommends checking the International Narcotics Control Board site for country-specific restrictions before any international trip with controlled drugs.⁶

If You’re a Foreigner Arrested on Drug Charges

Your passport does not shield you. The U.S. Embassy states it plainly: “If you break local laws in Mexico, your U.S. citizenship will not help you avoid arrest or prosecution.”⁷

Consular officers can give you a list of local English-speaking attorneys, contact your family or employer with your written consent, visit you in detention, and help you access medical care. They cannot get you out of jail, give you legal advice, represent you in court, pay fees, or intervene in the judicial process. Under the Vienna Convention on Consular Relations, Mexican authorities must notify the U.S. consulate of your arrest if you ask them to.⁸

If you don’t speak Spanish, you have a legal right to a translator throughout criminal proceedings under Mexico’s National Code of Penal Procedure. Quality varies widely in practice, and hiring your own bilingual attorney is more reliable than depending on court-appointed interpretation.

Deportation and Re-Entry Bans After a Drug Conviction

A Mexican drug conviction follows you after the sentence ends. Under Mexico’s Immigration Law, foreign nationals whose background is deemed to compromise national security or public safety can be deported and barred from returning. A drug conviction fits that category. The Instituto Nacional de Migración sets the length of the re-entry ban case by case, and for drug offenses it can be permanent.

Article 43 of the Immigration Law requires immigration authorities to reassess a foreigner’s status after any final criminal sentence. For tourists and temporary residents, that reassessment almost always ends in deportation once the criminal sentence is served. The immigration process is separate from and additional to the criminal penalty: you serve the time, then you leave.

For U.S. citizens, a Mexican conviction doesn’t automatically affect your status at home, but it can show up in future visa applications to other countries, professional licensing reviews, and security clearance decisions. For non-citizen U.S. residents, a foreign drug conviction can create inadmissibility and deportation problems on the American side as well, meaning a single arrest in Mexico can cost you your life in two countries.

1
Justia México. Ley General de Salud – Título Décimo Octavo – Capítulo VII
2
Suprema Corte de Justicia de la Nación. Elimination of the Absolute Prohibition of Ludic or Recreational Use of Marijuana
3
National Institute of Statistics and Geography. Unit of Measurement and Update (UMA)
4
Government of Canada. The Mexican Criminal Law System
5
U.S. Embassy & Consulates in Mexico. Bringing Items into Mexico / U.S.
6
Centers for Disease Control and Prevention. Traveling with Prohibited or Restricted Medications
7
U.S. Embassy & Consulates in Mexico. Legal Assistance and Arrest of a U.S. Citizen
8
U.S. Department of State Foreign Affairs Manual. 7 FAM 420 Notification and Access