Naltrexone Pills: A Comprehensive Guide


Naltrexone pills offer an affordable and convenient way to battle your way through opioid or alcohol addiction, but achieving the effects you need requires strict adherence to your doctor’s instructions.

In today’s comprehensive guide, we’ll explore naltrexone, its mechanism of action, appropriate dosages, missed dose management, side effects, and essential precautions.

Understanding the benefits (and risks) of naltrexone can go a long way in mentally preparing the patient for the treatment ahead so they can make an informed decision on whether they should begin naltrexone therapy.

What Are Naltrexone Pills?

Naltrexone pills are the oral form of naltrexone. The medication can be taken as pills or as a monthly extended-release injectable dose.

Both forms provide more or less the same effect, as both of them are effective in treating alcohol and opioid dependence. However, deciding which form is better for the patient is often up to the doctor and, to some extent, the patient.

Naltrexone Pills vs Injectable Naltrexone

While both forms of naltrexone provide the same effect, the route administered can be a pro or a con based on various factors.

Examples of these factors are the patient’s physical and mental condition, extent of opioid usage, as well as preference and financial considerations.

Naltrexone Pills

Oral naltrexone offers the following advantages

  • They are often more convenient to people compared to needles.
  • They are less expensive.
  • Because they’re often taken daily, it’s easy to phase them out of therapy (under the doctor’s supervision).

On the other hand, here are the disadvantages of naltrexone pills:

  • The daily intake is a hurdle for some people.
  • There’s a risk of missing or taking an extra dose by accident.
  • It’s not suitable for people who find difficulty in swallowing, like people with dry mouth, dysphagia, and those who suffer from fear of choking.

Injectable Naltrexone

Some people still prefer the injectable naltrexone for the following reasons:

  • It’s a much less frequent dose, typically just once a month.
  • It’s a good solution for those who keep forgetting their dose. You only take it once a month and forget about it.
  • It’s more suitable for people who have problems swallowing.

It does have its disadvantages, though, which include:

  • It’s an injection. It’ll always be painful and can be a nightmare for those who have needle phobia.
  • It’s more expensive than using naltrexone pills.
  • If you need to stop, you can’t easily discontinue it, as the effect will last for an entire month.

Note: The mechanism of action and the potential for side effects is relatively the same for both routes of the medication. The only major difference is that the injectable form’s effect is much longer than the pills.

Naltrexone: The Appropriate Dose

Naltrexone pills are typically 50 mg, which is also the standard dosage of naltrexone that should be taken every day or at least three times a week.

However, many factors can affect the dose. These factors include but aren’t limited to:

1. Age

Beyond 40 years old, the naltrexone dosage may need to be lowered. The older the patient is, the lower the dose they may be able to have.

2. Kidney and Liver Functions

The kidney and the liver work hand in hand to break down and eliminate any medication intake. Some medications are harder for both organs to deal with, and naltrexone is one of them.

If the patient has kidney and liver problems (like kidney failure or liver cirrhosis), they must inform their doctor so they may adjust the dose or put the patient on another drug.

3. Medications

Naltrexone isn’t a critical drug. It doesn’t cause addiction, and it’s not easy to reach a lethal overdose while using it.

However, it can interact with many other prescription and OTC medications. For example, methadone or buprenorphine (which are also used to treat addiction) can interact with naltrexone and cause undesirable side effects.

This makes it crucial for the patient to share their entire medical history and current prescriptions before naltrexone therapy.

4. The Purpose of Using the Drug

Naltrexone is approved by the FDA to help in treating opioid use disorder (OUD) and alcohol use disorder (AUD). The usual dose is 50 mg per day. However, naltrexone has some off-label uses.

One of the most common off-label uses is pain relief, but only if the origin of the pain is related to inflammation. This is common in some cases, like fibromyalgia.

While the typical dose of naltrexone can range from 25-50 mg per day, using it for mediating inflammatory pain calls for doses as low as 3-5 mg per day.

5. The Timing of the Dose

Patients who are using naltrexone to help with OUD or AUD for the first time are often prescribed a lower dose, which is typically 25 mg per day.

The idea is to minimize the side effects and gradually get the body used to naltrexone therapy.

Also, naltrexone should be given after the symptoms of opioid withdrawal have passed. As such, the closer the patient is to the last opioid dose, the more likely they’ll be prescribed a lower dose.

How to Handle a Missed Naltrexone Dose

The ideal routine to take your naltrexone pill would be at the same time every 24 hours. Sticking to this strict routine can be difficult in a fast-paced life.

In this section, we’ll show you what to do when you miss a dose and how to take the necessary precautions to prevent that from happening again, or at least minimize the chance.

Missing a Dose

If you miss a dose, you should take it as soon as you remember. If you remember missing it within 2-3 hours, then take the missed dose.

Do your best to take the missed dose as early as possible because naltrexone has a short half-life of only 10 hours. In other words, after 24 hours, the effect of a naltrexone pill would have stopped entirely.

If you’re too far ahead beyond the dose’s timer, say 8-10 hours, it’s best to skip the missed dose. Taking your missed dose too late and your next dose on time can increase the already bothersome side effects of naltrexone.

If you forget about your naltrexone pill for a whole day, you should never double the dose in order to “catch up” with the missed dose. The only thing you’ll be doing is increasing the side effects and causing a risk of an overdose.

How to Reduce the Incidence of Missed Doses

The following precautions will ensure that you get your naltrexone pill every day on time:

  • Select a suitable time of the day when you’re not too busy or sleeping. For example, if you’re an early bird, timing your pill after breakfast can easily integrate it into your daily routine.
  • Setting a reminder (or multiple) on your phone can be a great idea regardless of the time of day you choose. If you’re too busy or simply can’t remember, your phone will always point out when it’s time.
  • Keep a few naltrexone pills with you at all times. That way, if you’re not at home for any reason when it’s time for your dose, you’ll always have some backup.
  • If you’re taking other pills, a pillbox can be a great idea to help you keep track of all your medications.

Important note: If you miss your dose more than 2-3 times within a couple of weeks, you should get back to your doctor. They will run a quick diagnosis to check your physical condition and may adjust your dose.

Side Effects of Naltrexone

Naltrexone is one of the most common drugs for opioid and alcohol dependence. Being FDA-approved also reinforces its overall safety. However, that doesn’t mean it doesn’t have side effects.

Some of these side effects are common and, despite being annoying, aren’t a significant cause for concern. There are also some less common and rare side effects that you should keep an eye out for.

Common Side Effects

Most patients who undergo naltrexone therapy will experience one or more of the following side effects:

  • Nausea: Upset stomach and vomiting are very common with naltrexone, especially when taking the drug for the first time. Taking naltrexone with food can help reduce the feeling of an upset stomach.
  • Headache: Headache is another common side effect, particularly the tension headache. Fortunately, the severity of the headaches isn’t too bad, and it often goes away after a few hours of taking the pill.
  • Dizziness: Dizziness is less common than nausea and headache. Some naltrexone patients report feeling lightheaded for a few hours after taking the pill. The best approach to handle this is to refrain from changing your position or getting up suddenly, especially if you’re anemic.
  • Anxiety: Anxiety while taking naltrexone is highly dependent on the patient’s mentality. Patients who are doubtful or apprehensive about the treatment may feel anxious after taking the medication. Reassurance and relaxation techniques can help mediate this feeling.
  • Generalized Fatigue and Insomnia: In the first week of taking naltrexone, patients may feel too exhausted to stay awake but also too alert to fall asleep. This feeling is often mild and can go away with controlled breathing exercises and relaxation.
  • Loss of Appetite: The blocked opioids prevent both exogenous and endogenous opioids from improving the patient’s mood. Pair that with the nausea and headache, and food won’t seem appetizing to many patients.

Report any side effects you feel to your doctor. Based on your condition, they may offer better advice to handle the condition.

Less Common Side Effects

The following side effects are less common than the aforementioned ones. However, in most cases, they tend to happen simultaneously with them. They include but aren’t limited to:

  • Constipation or diarrhea: Naltrexone can cause altered bowel movements, which can either manifest as constipation or diarrhea. Maintaining water and fiber intake will reduce the instances of bowel irritation.
  • Mood swings: Your opioid receptors are blocked, and a large contributor to your mood regulation is blocked with them. It’s normal for people who take naltrexone to feel aggravated, angry, and distressed.
  • Dry mouth: Naltrexone may cause a sensation of dryness in your mouth. Fortunately, this is easy to manage by having a bottle of water around you at all times. Don’t wait until you feel the dryness; make a habit of sipping water every once in a while.
  • Joint and muscle pain: it’s not uncommon for naltrexone users to experience some pain in different parts of their body. Much like nausea, this feeling goes away as the body gets used to the drug.
  • Skin rash: First-time naltrexone users may have a mild-moderate skin rash in random parts of their bodies. Avoid scratching the skin if that happens to prevent skin damage, and try to keep your skin moisturized using over-the-counter skin creams/ointments.

Note: while we did provide some guidelines to handle these side effects, they don’t replace the doctor’s advice. Report any of the aforementioned side effects to your doctor because you may require dose or lifestyle adjustments.

Rare Side Effects

The following side effects are rare and are less likely to manifest in physically healthy individuals. However, the risk is still there. You should keep an eye out for the following:

  • Severe allergic reactions: if you experience any signs of allergic reactions after taking a naltrexone pill, you should immediately inform your doctor and call for help. Familiarizing yourself with allergy symptoms can help you spot them early so you can call for help before they get worse.
  • Pain around the liver: If you get a lingering pain under your stomach accompanied by yellowed skin or eyes, then you may be experiencing liver damage. This must be immediately reported.
  • Suicidal Thoughts: If the negative emotions you experience while on naltrexone progress to thoughts of self-harm or suicide, you should seek company, call for help, and inform your doctor as soon as you can.

Naltrexone’s side effects are often mild and temporary. Doctors also screen their patients well enough to refrain from prescribing naltrexone if they see a risk for those severe side effects.

Naltrexone is safe for the most part. The information above is to inform you, not to scare you.

Precautions While Taking Naltrexone

Putting all the possible side effects aside, there are still a few things to keep in mind during naltrexone treatment:

1. Naltrexone Therapy Should Never Begin During Withdrawal Symptoms

The patient will start to experience withdrawal symptoms around two days after the last opioid dose. Such symptoms will manifest physically and mentally, and they can make the following week difficult.

Withdrawal symptoms typically last for 7-14 days, depending on the type of opioid drugs taken and the duration of the addiction. The patient must wait until the symptoms disappear or at least subside before taking naltrexone.

Should the patient take naltrexone during this period, the withdrawal symptoms will be amplified and will last longer.

As such, the patient should go through this period under supervision and counseling. If that’s not possible, gradually transitioning the patient through these withdrawal symptoms can be a feasible idea.

Partial agonists like buprenorphine will partially activate the opioid receptors and give the patient some relief, which can aid through the withdrawal phase.

2. It’s Not a Direct Treatment

Despite being one of the most popular drugs to handle addiction, naltrexone doesn’t cure you from addiction the way other medications cure you from illnesses.

What this drug does is help you take the next step after the withdrawal symptoms have stopped. During this phase, the patient will have severe cravings, and they’ll think about opioids day and night.

That’s when naltrexone can help make opioids less desirable, and that’s why it’s a medication-assisted treatment. It won’t work on its own; it needs medical supervision, emotional support, and counseling.

3. It Shouldn’t Be Used With Other Opioid Containing Medicines

Naltrexone can interact with other opioids and various other medications. Some of these interactions are predictable, but most can be risky.

Naltrexone can even interact with some of your regular OTC drugs. Because of that, you need to be transparent with your doctor if you are taking any medications before they prescribe naltrexone to you.

4. It Can Indirectly Cause a Lethal Overdose

We mentioned earlier that it’s fairly hard to overdose on naltrexone itself. However, the drug can indirectly cause a patient to have an opioid overdose through two methods.

The first is when the patient loses their will and decides to go back on opioids during the naltrexone treatment. Because their opioid receptors are blocked by naltrexone, the opioids they take will achieve minimal to no effect.

With the negative emotions, frustration, and extreme cravings, the patient may take another opioid dose in hopes of getting the feeling they seek. This could be fatal.

The second scenario occurs when the patient has been on naltrexone for a long time. This scenario implies that the patient now has increased opioid sensitivity, which means the regular dose that the patient used to take without any issues can now cause a fatal reaction in their body.

As such, it’s absolutely paramount to avoid taking any opioids during naltrexone therapy without letting your doctor know about it.

5. It Should Be Avoided During Pregnancy and Breastfeeding

Both the oral and injectable forms of naltrexone shouldn’t be used if the patient is pregnant or breastfeeding. If you are planning to be pregnant, it’s also contraindicated to use naltrexone.

There aren’t enough studies to prove whether the drug can negatively affect you or the baby, so your doctor should assess whether or not it’s worth the risk.

6. Liver Enzymes Should Be Monitored

If you’re going to take naltrexone for a while, your doctor will probably request that you constantly check various body functions, including your liver enzymes.

We mentioned earlier that liver issues are one of the side effects associated with naltrexone use. It’s always a good idea to detect that the drug is badly affecting the liver before symptoms manifest.

As such, the patient must not ignore those liver function tests.

7. The Patient May Need to Be Tested for Allergies

Some people are more susceptible to allergic reactions than others. If the patient is known to have negative physical reactions to a few allergens, performing an allergy test for naltrexone to rule out hypersensitivity is a good idea.

This is important before taking naltrexone pills, but it’s even more critical before extended-release injectable naltrexone.


How Do I Store Naltrexone Pills?

You should store naltrexone pills in a closed container at room temperature.

Ensure that the drug is away from children and pets, as ingestion can lead to unpredictable effects.

What Are the Ingredients in a Naltrexone Pill?

The active ingredient in a naltrexone tablet is naltrexone hydrochloride. There’s also a list of inactive ingredients (fillers) that vary depending on the generic formulation of different brands.

However, you should typically find:

  • Magnesium stearate
  • Lactose monohydrate
  • Titanium dioxide
  • Polyethylene glycol
  • Hypromellose
  • Colloidal silicon dioxide
  • Yellow and red ferric oxide

Am I Allowed to Drink Alcohol During Naltrexone Therapy?

Whether you’re taking naltrexone for OUD or AUD, consuming alcohol is not recommended.

It will increase the risk of side effects, reduce the efficacy of naltrexone, and interfere with the overall treatment goals.

Final Words

While the information in this article can give you a much deeper look into naltrexone therapy, it does not replace a doctor’s guidance.

People are different, and doctors may tailor a treatment for a patient whose condition is special. Sometimes, naltrexone might be taken off the table completely.

If you or someone you know is about to take naltrexone pills, it’s paramount to adhere to the instructions and to keep up with the doctor.


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