Methadone has been FDA approved for over 50 years and is used all around the world. There is plenty of research into the safety and side effects of this medication.
Methadone is generally well tolerated. And, side effects can usually be relieved, sometimes even without additional medications. The side effects also tend to get better over time, as the dosage of methadone is stabilized.
The Most Common Side Effects of Methadone
Side effects reported by 50-80% of patients:
Additional side effects reported by 30-50% of patients:
Despite these side effects, research shows that the physical health of patients improves on methadone. ⓘ
Opioids are known to cause constipation. Many patients relieve this side effect by dramatically increasing their intake of fiber and water, but sometimes laxatives or even prescription medications are required.
To alleviate methadone-related constipation:
Dry mouth can be an annoying side effect of methadone. There are various lozenges and rinses to help relieve dry mouth, but many patients find Biotene moisturizing spray the most helpful. It is over-the-counter and can be purchased online or at most pharmacies.
Patients that don’t experience dry mouth symptoms cite consciously drinking extra water (which helps with any constipation side effects too). If dry mouth symptoms are worse in the morning, try keeping water or ice by the bed.
Also, be sure to practice good oral hygiene because dry mouth contributes to cavities and mouth sores. General dental recommendations include brushing twice a day thoroughly with fluoride toothpaste and flossing daily, as well as limiting sugary drinks and tobacco.
Daytime sleepiness can be intense with methadone. But, getting on the proper dosage of the medication will help. (Too little methadone can cause opioid withdrawal fatigue and too much can cause fatigue from the medication). Patients report decreased fatigue after four months of methadone treatment. ⓘ
Sleep issues contribute to daytime sleepiness, including the liability to fall asleep and nighttime waking. Practicing good sleep habits will improve your daytime energy. Here are some tips:
Learn more: Opiate Insomnia
Studies show sweating is a common side effect of methadone, but it can also indicate that the dosage is too high. Therefore, simply lowering the methadone dose may alleviate this side effect, if possible.
Several meditations can be used off-label to help with sweating from methadone, including Oxybutin and desloratadine.ⓘ Stronger deodorants are also available as a prescription. And, like many other side effects, water is helpful for excessive sweating too.
Trouble urinating on methadone can be caused by the loss of fluids from excessive sweating if both side effects are experienced at the same time. The prescription medication arginine vasopressin helps regulate the amount of water in your body.ⓘ
Itchy skin is not a side effect we see in many methadone patients. This side effect seems to be experienced by those also experiencing sweating and that also already have underlying skin issues like eczema. Sweating causes dryness and triggers eczema flare-ups. A good moisturizer should help. The creams from the brands CeraVe and Nivea are often recommended and easily available. Look for anything thick.
If nausea is felt after taking methadone on an empty stomach, try eating prior to dosing.
If nausea is felt after taking methadone on a full stomach, Ondansetron (Zofran) can be a helpful prescription medication to ease this side effect. As with most of these side effects, adjusting the dosage can also help.
If nausea is felt before taking methadone, it’s likely caused by opioid withdrawal and not the medication. Increasing the medication dosage or split dosing could help.
The length of menstrual cycles can be impacted for around half of women starting methadone but normalizes as the dosage is stabilized. One historic study shows 99% of women resumed regular menstruation while on methadone.ⓘ
Even patients on high levels of methadone are able to conceive and the medication does not impact pregnancy. In fact, methadone is recommended for pregnant women using other prescription opioids or heroin. Like all side effects, female processes are much less distributed by methadone than opioid abuse.
See also: Opioid Use While Pregnant
I’ve heard patients call this methadone side effect “pirate eye,” where it can be tough for the eyes to focus. Like most other side effects from methadone, blurred vision tends to go away, often by the third week.
Double-vision can also contribute to nausea and lightheadedness side effects.
Long-standing use of methadone can cause a condition called long QT syndrome (LQTS), which presents as a fast irregular heart rate. In general, a resting heart rate of more than 100 beats per minute (BPM) is considered too fast for an adult.
If a patient develops LQTS, they should lower their dose or discontinue methadone altogether and try another medication. Prescription beta blockers or surgery could be appropriate long-term treatments for LQTS.
Long QT EKG Example
LQTS is most likely to occur when high doses of methadone are taken over many years. The ideal methadone maintenance dose is 60-100 mg. Significantly exceeding the established recommendation can weaken the heart and cause serious and permanent heart issues including LQTS or coronary artery disease.ⓘ
See also: Methadone Dosages
Anyone with a cardiac history should be sent for a cardiac workup before continuing indefinitely on methadone. We would usually start the patient on methadone to stop the illicit use while waiting for cardiac clearance to continue long-term. The risk of overdose with the potency of opioids these days is too high to delay starting the medication.
Heart issues can be accompanied by lightheadedness or even fainting and should always be investigated to ensure there are no underlying issues with the heart, though these side effects are not always found to be serious.
Methadone Side Effect FAQs
There tend to be many questions about methadone use because it’s one of the most highly regulated medications. However, the concern is not related to side effects but the potential for misuse. For most patients, the benefits are going to outweight any potential side effect.
Depression is highly related to opioid addiction and methadone actually helps.
Increased risk factors for depression in methadone patients include:
- Female gender
- Taking psychiatric medications
- Abuse or prescription of benzodiazepines (including Xanax, Valium or Klonopin)
- Methadone doses of more than 120 mg per day
After four months of methadone treatment patients report feeling less depressed.ⓘ
A 2015 study shows that those on methadone have the same levels of working memory, mental flexibility and processing speed as healthy adults that have never used methadone.ⓘ
While methadone patients have also been shown to have a lower capacity in some brain functions (like self-control and emotional regulation), it’s possible some of these deficiencies lead to addiction or were caused by opioid abuse instead. Opioid abuse is more damaging to the brain than properly prescribed methadone.
A recent study shows BMI increased 1.9 points on average for those on methadone maintenance.ⓘ (If you were 5 feet 5 inches, 1 BMI point equals around 6 pounds).
Some opioid addiction patients are underweight when starting methadone treatment. But, for those looking to avoid weight gain while on methadone, it’s not actually impacted by the dose of methadone, but rather by a poor diet, including excessive sugar.
Before starting on methadone, providers should do a Comprehensive Metabolic Panel (CMP) to check for baseline kidney and liver function. But, since methadone is mostly metabolized by the liver, even those with kidney issues are typically cleared for methadone use.
Kidney issues derived from methadone use are extremely rare and occur when methadone is abused or in patients with underlying kidney diseases or HIV. (A methadone prescription is much less damaging to the kidneys than opioid abuse).ⓘ
No, neither paranoia nor hallucinations are a side effect of methadone. Though, those on high doses of methadone are more likely to have a co-occurring psychiatric disorder that should be treated separately.ⓘ
In rare cases, psychosis can be a temporary side effect of opioid withdrawal or high levels of opioid use, but not a side effect of using methadone.ⓘ
Methadone is used for pain relief. The medication doesn’t cause headaches, though opioid withdrawal can cause headaches.
Anger issues are not a side effect of methadone use.ⓘ An MAT therapist can help you determine where feelings of anger or the inability to control anger is coming from and how to manage anger issues.
Patients using methadone to treat chronic pain have significantly higher frequency and severity of nausea, vomiting, diarrhea, decreased appetite, sweating and itchy skin, compared to those using methadone to treat opioid addiction.
(Whether treating substance use or chronic pain, patients that were previously using other opioids also report a higher frequency and severity of symptoms than those who have not been using other opioids prior to taking methadone).ⓘ
Get Help For Methadone Side Effects
Every methadone provider should be helping patients with any bothersome side effects of the medication. But, even well-meaning government-funded clinics like Family Guidance Centers can feel like “dose-and-go” with long lines and little staff. That’s not how it works here.
Methadone Clinics that Care
Illinois Methadone Clinics
Texas Methadone Clinics
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