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How Long Does 5-HTP Stay in Your System? A Doctor Explains…

Are you interested in the serotonin precursor 5-HTP? Or already taking it? Then, you might be wondering how long does 5-HTP stay in your system – and, since there’s a lot of contradicting information on the topic, I’m here to set the record straight.

Welcome to a comprehensive guide on 5-Hydroxytryptophan or 5-HTP for short. As a precursor to the neurotransmitter serotonin (which regulates mood, sleep and appetite among others), this supplement can help you manage conditions like depression, anxiety, or insomnia. However, it also comes with some risks like serotonin syndrome – and, to prevent them, it’s important to know how long it lasts in your system:

5-htp supplement action graphic

To give you a quick answer it takes up to 7-8 hours to clear half of the 5-HTP you took in your system. Most of the 5-HTP will be gone in up to 40 hours (or about 1.5 days) after you take it.

However, this applies to the 5-HTP you took as a supplement. Since this is also a naturally occurring substance, it’s never really gone from your system. But, for the purpose of knowing when side effects might clear or when you’re less likely to suffer drug interactions, this is the clearance information that matters.

In this article, we’ll go on a deep dive into what 5-HTP is and how it functions in the body. This will help you understand how long it lasts in your system – and why that’s useful when you figure out your dosing regimen. So, here is what’s coming up:

What is 5-HTP?

5-HTP is a precursor to serotonin, a neurotransmitter that plays a vital role in regulating our mood, appetite, and sleep. Basically, 5-HTP is the building block your body needs to produce more serotonin.

You might have come across 5-HTP while searching for natural ways to improve your mood or get better sleep. It’s commonly found in supplement form and is derived from the seeds of an African plant called Griffonia simplicifolia. People often turn to 5-HTP for a range of issues—from lifting the clouds of mild depression to catching those elusive Z’s at night and even treating less common concerns like fibromyalgia.

Keep in mind that 5-HTP is a supplement, not a drug. Unlike anti-depressants, which boost serotonin directly, 5-HTP supports the neurotransmitter levels indirectly. There is an inherent level of guesswork when it comes to supplements because the FDA doesn’t regulate them in the same way they do drugs.

Unlike drugs, we don’t have enough proof that 5-HTP is effective to treat or prevent disease. There is a lot of anecdotal evidence and people on mental health groups, Reddit and Amazon reviews report solid results. However, this supplement can’t (and really isn’t meant to) replace actual pharmacological therapy.

Where am I going with this? Well, to the expected disclaimer. This article isn’t medical advice and it’s definitely not telling you to skip your antidepressant to take 5-HTP. As a supplement, 5-HTP is exciting (and, personally, I think it has some interesting benefits), but still go by what your healthcare provider tells you – they’re the person who knows your medical history best.

How Does 5-HTP Work in the Body?

Once you ingest a 5-HTP supplement, it travels through your bloodstream and crosses the blood-brain barrier. This is a crucial step because it allows 5-HTP to access the brain, where it’s converted into serotonin.

Why not take serotonin directly, though? That way you can skip the conversion step. Well, unfortunately, serotonin does not cross the blood-brain barrier so it can’t act on your brain function directly. That’s also the reason why anti-depressants aren’t serotonin but serotonin reuptake inhibitors (meaning more of your serotonin is leftover to act on nerve cells).

Going back to 5-HTP – how long until you feel the 5-HTP effect?

The answer varies from person to person, but generally, the effects can be felt within 30 minutes to an hour after ingestion. The duration of these effects is a different story, and that’s what we’ll delve into next. And, depending on your health goals, it can also take much longer than 30 minutes to see a lasting impact (e.g., one diabetes study people ate less on 5-HTP, but the 400-calorie daily difference would take weeks before they see weight loss).

So, let’s talk about 5-HTP and how long it lasts in your system:

How Long Does 5-HTP Last in the Body?

When the talk about supplements and drugs, we often touch on half-life instead of “complete life” (in truth, complete life isn’t even a term). The information we have on 5-HTP is no different – it comes from a half-life study:

Understanding Half-life

Before we dive into the specifics, let’s clarify what “half-life” means in a pharmacological context. The half-life of a substance is the time it takes for half of it to be eliminated from your system.

In research, we’ve seen that the biological half-life of 5-HTP ranges from 2.2 to 7.4 hours. This means that if you take a dose of 5-HTP, approximately half of it will be cleared from your body within this time frame.

Complete Clearance Time (& How Often You Should Take 5-HTP)

Now, you might be wondering, “When will 5-HTP be completely out of my system?” To answer this, we generally consider about 4-5 half-lives for a drug to be almost entirely eliminated. Let’s take 8 hours as a half-life to be sage and multiply by five:

We get 40 hours for 5-HTP to be nearly entirely cleared from your system.

So, based on this, how often do you need your 5-HTP supplement? Well, you’d need to take it at least once every two days to have some level of extra 5-HTP in your system. However, this would mean huge fluctuations. At the end of the 40-hour period, you barely have any additional 5-HTP – then, a couple of hours later, you have very high levels.

That’s why the better recommendation is one to three times per day, depending on your concern. Let’s dig deeper into that one:

Factors That Affect the Duration of 5-HTP in Your System

Understanding how long 5-HTP stays in your system is one thing, but it’s also crucial to know that this duration can vary from person to person. Several factors can influence how quickly your body processes and eliminates 5-HTP (and the difference can be very significant):

Medical Conditions & Age

As you age, your metabolism tends to slow down. That’s why 5-HTP metabolism will be slower in older people and they’d be at the upper limit of that half-life range (so about 7.4 hours).

The same goes for liver disease, which changes the way (and efficiency) of how you metabolise foreign substances. For somebody with liver issues, it can be a challenge to clear the 5-HTP they ingested. This is why the 5-HTP supplement is not recommended if you have any hepatic conditions.

Metabolism and Individual Physiology

Your metabolic rate—how quickly your body processes substances—goes beyond medical conditions, too. Factors like age, weight, and overall health can influence your metabolic rate. We already covered age, but there are multiple other factors.

In general, the younger and healthier you are, the faster your metabolism BUT there may be additional biochemical issues at play. Some people, for instance, are slow metabolisers without having any medical conditions. Caffeine is a good example here. For some, it takes over 9 hours to metabolise 50% of the caffeine.

5-HTP may be similar for you and there’s no way of knowing before you start the supplement. This is why it’s best to start at a lower dose and watch how you react. Even though it’s a supplement, 5-HTP can have some unpleasant side effects and this is the best way of minimising them.

And, again (this should go without saying), talk to your doctor first, especially if you have other conditions. They can guide you toward the best way for you to take 5-HTP.

Method of Administration

Finally, an additional disclaimer.

As a supplement, most people take 5-HTP orally. However, in half-life studies, the substance is usually administered intravenously. The method of administration can influence how quickly it’s absorbed into your bloodstream and, consequently, how long it stays in your system.

Oral administration generally has a slower absorption rate compared to intravenous methods. That’s why you should take the upper number of the half-life when you’re taking the supplement by mouth. More than safety, this also helps account for the IV versus oral intake difference.

When it comes to taking 5-HTP, one size definitely doesn’t fit all. The right dosage can vary based on several factors, including the condition you’re looking to manage and your individual physiology. And, to make things even more complex, there simply isn’t a lot of research on this (reason why 5-HTP is a supplement and not a drug.)

Dosage for Specific Conditions

Here are the doses of 5-HTP that have been used in different studies on the supplement:

  • Improving mood: 100mg, twice a day; 200mg per day total.
  • Better sleep: 100mg per day (best to take it before bed) for at least 4 weeks
  • Weight management: 250mg, three times a day (30 minutes before a meal); 750mg per day total
  • Preventing migraines: 600mg per day for at least six months.
  • Treating fibromyalgia symptoms: 100mg, three times a day for at least 2 weeks (300mg per day)

Anxiety, which is another big reason people take 5-HTP, can improve with even 50mg per day. There isn’t a lot of high-quality research there but positive reviews seem to show good response.

You can now buy 5-HTP supplements as low as 50mg per pill and this is the dose I recommend. Start with 50mg and build it from there, especially if your concern is mood or sleep. For things like migraines prevention that dose may be low so do talk to your physician about a higher dosage. But, for mood and sleep (which is what most people pick up 5-HTP for), it’s a great baseline.

Psst! If you’re looking for help with weight management, check out the berberine supplement, too. I recently did a piece where I compare it to metformin (and I have to say it’s pretty promising).

Adjusting Dosage Over Time

It’s also worth noting that you may need to adjust your dosage over time. Your body can build a tolerance to 5-HTP, or your symptoms may change, requiring a dosage adjustment.

To prevent this, some people choose to only take 5-HTP 3-4 days a week and then to give themselves a couple of days before the next dose. Considering it can take up to two days for all the extra 5-HTP to clear from your system, this is a good idea.

On the flip side, some uses require larger doses for a longer period of time (like migraines prevention). If you fall into one of these categories, I’d suggest starting with the 50mg per day dosage and building from there. In any case, please take your doctor’s advice over anything I tell you here – your healthcare provider can give you specific tips that work for you.

Side Effects and Precautions

While 5-HTP has many potential benefits, it’s essential to be aware of the possible side effects – if you notice any of them, consider lowering the dosage and taking 5-HTP less often. Give yourself a couple of days off the supplement so the 5-HTP can leave your system and then retry at a lower dose.

Common Side Effects

  • Nausea and Vomiting: These are among the most common side effects and usually occur when you first start taking 5-HTP.
  • Digestive Issues: Some people experience stomach cramps or diarrhea, especially at higher doses.
  • Drowsiness: Since 5-HTP can promote relaxation and sleep, it may cause drowsiness. Be cautious if you need to drive or operate heavy machinery.

Special Precautions

Here are two cases where you shouldn’t take 5-HTP unless your doctor specifically clears it for you:

  • Pregnancy and Breastfeeding: The safety of 5-HTP during pregnancy and breastfeeding is not well-studied. I would steer clear completely.
  • Interactions with Medications: If you’re taking antidepressants or other medications that affect serotonin levels, combining them with 5-HTP can lead to serotonin syndrome, which is potentially life-treatening. Some psychiatrists work with this combination for their patients but this isn’t something you should initiate alone. The same goes for any other prescription medication you are on. 5-HTP might be a supplement but it still has interactions, so double-check with your doctor before adding it to your routine.
  • Alcohol: Alcohol can increase the serotonin levels in your brain, making it a dangerous combo with 5-HTP (which also boosts serotonin). So, no, you can’t drink alcohol and take 5-HTP. Ethanol takes up to 12 hours to completely clear from your blood, so don’t take 5-HTP until 12 hours have passed from your last drink. And, wait for 40 hours (or two days to be safe) after your last 5-HTP dose before drinking.

When to Consult a Healthcare Provider

If you experience any severe or persistent side effects, it’s crucial to consult your healthcare provider immediately.

Watch out for serotonin syndrome in particular. For this condition, symptoms typically start within 1-6 hours of taking the drug or supplement (and within 24 hours for nearly everyone). Tremors and involuntary muscle contractions (clonus) are two of the typical things to watch out for.

If you’ve taken 5-HTP and notice any of these, please go to see a doctor immediately:

  • Involuntary muscle contractions and tremor
  • Fever (temperature over 38 C)
  • Abnormal eye movements
  • Fast heartbeat and high blood pressure
  • Nausea, vomiting, or diarhhea

Learn more about serotonin syndrome by Dr. Tracey Marks’ amazing video:

Keep in mind that serotonin syndrome isn’t likely to happen from 5-HTP alone. However, if you’re drinking alcohol, taking antidepressants or any other serotonin-boosting medication, your chances go way up. Avoid these high-risk situations and get to a doctor if you feel any serotonin syndrome symptoms.

How to Maximize the Effects of 5-HTP

So, you’re considering taking 5-HTP and you’re well-informed about its duration, dosage, and potential side effects. The next logical step is to figure out how to get the most bang for your buck—or in this case, the most serotonin for your supplement. Let’s explore some actionable tips.

Timing is Key

  • On an Empty Stomach: Taking 5-HTP on an empty stomach can improve its absorption, making it more effective.
  • Time of Day: Depending on your goal—be it better sleep or mood improvement—the time you take 5-HTP can vary. For sleep issues, taking it before bedtime is advisable. For mood regulation, doses can be spread throughout the day (but I would still start at night, just in case it’s sedating for you).

Pairing with Other Nutrients

  • With Green Tea Extract: Some companies have come out with combination supplements of 5-HTP and green tea extract. Since green tea can have some positive effects for weight management, this is a good option if you’re trying to drop some pounds. You don’t have to buy a combo supplement to get the perks, though – you can just have a cup of green tea alongside your supplements.
  • With Vitamin B6: This vitamin can aid in the conversion of 5-HTP to serotonin, potentially making the supplement more effective. Once again, there are supplement options where you get both nutrients. You can also take vitamin B6 separately or at least enjoy some B6-rich foods in your diet like organ meats and fish.

Regular Monitoring

Finally, it’s always helpful to keep a log of how you’re feeling before and after starting 5-HTP. This can help you and your healthcare provider assess its effectiveness and adjust the dosage if needed. For some people, it can take a while to see an effect, so don’t become discouraged if it doesn’t happen right away.


We’ve covered a lot of ground today, haven’t we? From understanding what 5-HTP is and how it works in your body, to diving deep into its duration, dosage, and potential side effects. We’ve also explored actionable ways to maximize its benefits.

The key takeaway here is that while 5-HTP can offer various health benefits, it’s crucial to approach its usage with informed caution. It can take up to 40 hours for the supplement to clear completely from your system and there are some dangerous interactions.

By being well-informed, you can prevent potential side effects and react appropriately if anything does happen. Whether you’re considering 5-HTP to improve your mood, help you sleep better, or manage anxiety, understanding how it interacts with your body is the first step to achieving your health goals.

Thank you for joining me on this comprehensive journey through the world of 5-HTP. Let’s wrap it up by answering some of the most common questions relating to how long 5-HTP lasts in your body:

Will 5-HTP Show Up on a Drug Test?

No, 5-HTP is not a controlled substance and is not tested for in standard drug tests. It is a naturally occurring amino acid and a precursor to serotonin. Therefore, taking 5-HTP should not cause you to fail a drug test for substances like narcotics, stimulants, or other illegal drugs. But, if you are driving or operating heavy machinery, 5-HTP can still make you drowsy and it’s best avoided.

What Happens If You Suddenly Stop Taking 5-HTP?

If you suddenly stop taking 5-HTP, you may experience a return of the symptoms you were initially trying to manage, such as depression, anxiety, or sleep issues. However, 5-HTP is not known to cause withdrawal symptoms like some prescription medications. It’s always best to consult your healthcare provider for guidance on how to safely discontinue any supplement or medication.

Should I Cycle Off 5-HTP?

The idea of cycling off 5-HTP is a topic of debate. Some prefer to take breaks from 5-HTP to prevent potential tolerance, where the body becomes accustomed to the supplement and it becomes less effective. But in other cases consistent use is fine, especially if you’re trying to manage a chronic condition. The best approach is to consult your healthcare provider for personalized advice tailored to your specific needs.

What Happens If You Take 5-HTP During the Day?

Taking 5-HTP during the day is generally safe and may help with mood regulation and anxiety. However, one of the common side effects of 5-HTP is drowsiness. If you find that daytime use makes you feel sleepy or affects your ability to focus, you may want to adjust the timing of your dosage.

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