Heroin Withdrawal Timeline: Day by Day, and the Fentanyl in NJ Heroin

How long does heroin withdrawal last?

About 7 to 10 days for the acute physical part. That is the figure SAMHSA’s TIP 63 gives for withdrawal from short-acting opioids, and heroin is one. The first symptoms usually start within hours, and the worst of the physical symptoms usually arrive in days one to three.

In New Jersey, a bag sold as heroin is now usually fentanyl, and fentanyl does not keep heroin’s clock. The timeline below is the textbook one for heroin. Read it as the best case.

Heroin withdrawal timeline, day by day

Hours 8 to 24: the first signs

MedlinePlus lists the early symptoms as agitation, anxiety, muscle aches, more tearing, insomnia, runny nose, sweating, and yawning. People who use heroin call this getting dope sick; MedlinePlus lists “dopesickness” as another name for opioid withdrawal.

Days 1 to 3: the peak

The later symptoms are the hard ones: stomach cramps, diarrhea, dilated pupils, goosebumps, nausea, and vomiting. TIP 63’s grading puts fever, a fast pulse, and rising blood pressure in this stretch, and its most severe grade includes dehydration and low blood pressure. This is where the medical risk sits. MedlinePlus notes that vomiting and diarrhea can cause dehydration and mineral imbalances, and that vomit breathed into the lungs can cause a lung infection.

Days 4 to 10: easing

TIP 63 does not chart the days between the peak and the end. It gives a total of 7 to 10 days for short-acting opioids. It also says that after short-term supervised withdrawal, people frequently go back to using illicit opioids, which is what makes the next stretch dangerous.

After day 10: the dangerous part nobody feels

Opioid withdrawal is rarely fatal by itself, though tolerance falls within days, so a return to a former dose can be fatal. The lofexidine (Lucemyra) label states that people who complete opioid discontinuation are likely to have reduced tolerance and are at increased risk of fatal overdose if they resume. TIP 63 adds that after the initial withdrawal, many people have weeks or months of low mood, craving, poor sleep, and heightened pain.

Why New Jersey “heroin” does not follow the heroin timeline

More than 90 percent of drugs seized by New Jersey law enforcement over a recent two-year period tested positive for fentanyl, per the state’s Commission of Investigation, so assume a powder sold as heroin contains it.

That matters for timing. After regular use, fentanyl leaves the body slowly. In a 2020 study of 12 people entering treatment, urine took an average of about a week to test negative for fentanyl, and 19 days in one case. With regular fentanyl use, the timing of withdrawal is less predictable than the 8-to-24-hour window above, and the course can run longer than with heroin. Connecting slow clearance to how withdrawal runs is our reading of that study, not a measured withdrawal curve.

It also matters for medication. Buprenorphine, the drug in Suboxone, taken while fentanyl is still on the opioid receptors can set off sudden, severe withdrawal, called precipitated withdrawal. Feeling sick enough is no longer reliable proof of being ready. Our fentanyl withdrawal guide covers fentanyl’s clearance, low-dose buprenorphine starts, and what programs do differently.

The sedatives in the bag

The Department of Health alert found xylazine in one-third of suspected heroin and fentanyl seizures in 2022 and 45 percent in the first quarter of 2023. The Commission of Investigation reports that medetomidine, a newer veterinary sedative, had not been seen in New Jersey seizures before 2024, and that from January 2024 to May 2025 state forensic labs found it in 910 cases of suspected heroin.

Medetomidine can bring a withdrawal of its own that heroin never did. The CDC’s April 2026 health advisory lists a fast heart rate, severe high blood pressure, fluctuating alertness, tremor, chest pain, and vomiting that will not stop. Those are not dope sickness. They are reasons for an emergency room, and they are why the fentanyl guide spends a full section on them.

Heroin withdrawal symptoms

MedlinePlus describes these symptoms as very uncomfortable but not life threatening. The same page says that withdrawing from opioids on your own can be very hard and may be dangerous, and that it can happen at home with medicines and strong support, in a detox facility, or in a hospital if symptoms are severe.

Medication changes the timeline

The 7-to-10-day clock describes withdrawal with no opioid medication. That is not the only option, and TIP 63 does not treat it as the best one.

• Starting buprenorphine or methadone and staying on it. Both treat withdrawal and the opioid use disorder underneath it. TIP 63’s expert panel recommends offering maintenance treatment rather than short-term supervised withdrawal, and supports staying on medication for years if it is helping. Our Suboxone, Subutex and Sublocade guide compares the buprenorphine forms.
• A supervised withdrawal using buprenorphine or methadone. TIP 63 says either can be used for a withdrawal over days to weeks for people who prefer it. Its panel does not recommend short-term supervised withdrawal alone, because of high rates of return to illicit opioid use.
• Non-opioid comfort medicines. Lofexidine (Lucemyra) is FDA-approved to ease opioid withdrawal symptoms; its label says it is not a treatment for opioid use disorder. Clonidine is a related drug; see clonidine vs Klonopin.

The strongest argument for staying on medication is the death data. Pooled cohort studies in the BMJ (Sordo, 2017) and JAMA Psychiatry (Santo, 2021) found all-cause death rates about half as high or lower during time on methadone or buprenorphine than during time off them. The Sordo review also found sharply higher death rates in the weeks right after people leave opioid agonist treatment.

Can you go through heroin withdrawal at home?

Some people do, and MedlinePlus names home withdrawal as one setting while calling it difficult. Three things make it a riskier plan in New Jersey now: the bag is probably fentanyl, so the timing is harder to predict; a self-started buprenorphine dose can trigger precipitated withdrawal; and medetomidine withdrawal can turn into an emergency. Add pregnancy, alcohol or benzodiazepine use, or heart disease and the answer is a supervised setting.

If you are pregnant, do not stop opioids on your own. ASAM recommends treatment with methadone or buprenorphine rather than withdrawal for pregnant people who are physically dependent on opioids.

Whoever is around during and after withdrawal should have naloxone and know where it is. Our naloxone guide for families covers how to get it in New Jersey, and our guide to signs of heroin use covers what heroin and its paraphernalia look like.

In New Jersey

Heroin is a large share of the state’s treatment demand. In 2024 it was the primary drug at 23,408 of 81,217 treatment admissions reported to the state, about 29 percent, according to the Division of Mental Health and Addiction Services. Our opioid detox guide lists New Jersey’s licensed opioid-capable programs and walks through each way to pay.

Under New Jersey law P.L.2017, c.28, fully insured New Jersey plans and the State Health Benefits and School Employees’ plans cannot require prior authorization for the first 180 days per plan year of in-network treatment your own physician, psychologist or psychiatrist finds medically necessary, or, during those same 180 days, for outpatient prescription drugs that treat substance use disorder, such as buprenorphine and naltrexone, when that clinician finds them medically necessary. Self-funded employer plans, Medicare and Medicaid are not covered by that rule, so verify with the plan.

NJ FamilyCare covers buprenorphine, methadone, and naltrexone. Residential detox is authorized through the IME for most members, and residential care and opioid treatment programs are scheduled to move into the NJ FamilyCare health plans in January 2027.

For help independent of us, the state’s IME Addictions Access Center at 1-844-276-2777 screens NJ FamilyCare and uninsured residents and refers them to treatment, and ReachNJ, the state treatment line, is at 1-844-732-2465. Periscope Behavioral Health, which publishes this site, is opening a medical detox in Hammonton, Atlantic County, expected Summer 2027. Until it opens, Periscope Behavioral Health at (888) 313-3583, our publisher’s admissions line, can talk through options in New Jersey and Florida, including facilities Periscope operates. What a plan covers depends on the plan and the facility’s network status.

What the timeline leaves out

A withdrawal timeline answers how long the sickness lasts. It does not answer what keeps someone alive in the month after, which is where the death data on this page points.

When calling programs, one question sorts them quickly: how do you start buprenorphine for someone whose heroin was probably fentanyl? A program that does this often will describe a specific approach. A vague answer is a reason to keep calling. After that, ask whether it offers methadone, and whether people leave with medication, naloxone, and an appointment already booked.