ADHD

Is it ADHD or bipolar disorder? How to tell them apart

Fast mood swings do not tell ADHD apart from bipolar disorder. What tells them apart is the pattern over time.

By Dra. Daniela Málaga·September 15, 2026

There are stretches when you can handle anything: you answer fast, five projects occur to you at once, you sleep little and it does not seem to matter. And there are others when you cannot handle anything, and you do not quite understand what changed. In between you get distracted by everything, and your mood shifts several times a day.

That description fits adult ADHD and it also fits bipolar disorder. That is no coincidence: they share symptoms, and telling them apart with the usual clinical assessments is difficult, for professionals too. Which is why it is worth knowing what separates them: the path each one takes is different.

The difference is in the pattern, not in the intensity. ADHD is a steady pattern going back to childhood or early adolescence: mood changes are brief, usually respond to something during the day, and return to normal within a few hours. Bipolar disorder comes in episodes lasting days or weeks, with a return to baseline between them.

Do fast mood swings mean bipolar disorder?

Not necessarily, and this is the counterintuitive part. In a study comparing sixty adult women with ADHD, with bipolar disorder and with neither, emotional instability was elevated in both clinical groups, and the comparisons did not separate them. In other words: “I am very emotionally unstable” does not tip the scale either way.

Something similar happens with mania rating scales, and the authors warn they should not be used on their own to diagnose.

But the same study found something that does work, and this is the useful part: symptoms specific to bipolar disorder do help separate it from ADHD when you ask about the worst episode in the past, rather than about how the person is today. “How have you felt this week?” is not the same question as “was there a stretch of your life when you were very different?”. The second one is the one that actually points somewhere.

It is worth knowing where these data come from, because they have real limits: sixty women, the bipolar group was in a stable phase and stayed on their medication, while participants with ADHD were asked to stop their stimulant forty-eight hours before the assessment. That asymmetry matters when reading the result. It helps you understand why telling them apart is hard, but it does not settle anyone’s diagnosis.

The fact that mood stays altered outside the episode is not a quirk of that study. Another one, with 67 adults of both sexes with bipolar I disorder who were interviewed monthly until remission was confirmed, found they still scored higher on negative and positive emotion than people without the disorder, and that this emotionality went together with more mood fluctuation. That study did not include an ADHD group, so it cannot tell you which is which: what it shows is that the emotional disturbance is still there between episodes, which is part of why unstable mood, on its own, tells you so little.

How ADHD is told apart from bipolar disorder

These are the signals a specialist looks at in the differential diagnosis. None works on its own, and a missing one rules nothing out.

First is the course over time, which is the most useful criterion and the one that almost never shows up in online tests. Adult ADHD is a chronic, trait-like condition that emerges out of childhood or early adolescence, and its symptoms are usually stable over time. Bipolar disorder works in episodes; its peak age of onset is between fifteen and nineteen, in late adolescence or early adulthood, although it can appear earlier or later. One clarification, because it causes confusion: ADHD starting in childhood does not mean the diagnosis arrives early. Many adults only notice the problem when the load increases, with a new job, parenthood or postgraduate study, after years of compensating with structure and effort.

Then there is how long the mood change lasts, which is the most concrete difference. In ADHD changes usually last hours and return to baseline. To speak of an episode, by contrast, the British guideline asks for four consecutive days or more in the case of hypomania, which is the milder form of that elevated mood state, and seven or more for mania, which also requires marked functional impairment or psychotic symptoms. And they are not scattered days: the change has to be there most of the day, nearly every one of those days. A bad afternoon, or an odd day, is not an episode. And in ADHD mood usually reacts to something specific during the day, moving within a poorly regulated but essentially normal range, not the extremes of depression and elation seen in bipolar disorder.

Sleep gives another clue. When someone with ADHD sleeps little, they feel it: there is tiredness and discomfort. In a manic phase the need for sleep drops, often without any physical discomfort. It is not “I slept badly and I am exhausted”, it is “I slept very little for several days in a row and I feel great”. It is easy to confuse this with something else: in adult ADHD what is common is that falling asleep takes a long time and that daytime sleepiness is higher the next day, while total sleep duration does not differ from someone without ADHD. In ADHD the problem is usually getting to sleep and carrying tiredness around; in a manic phase, sleeping less and not missing it.

It also matters that other people noticed it. An episode involves a change the people around you can see. That said, nobody noticing does not rule it out either: sometimes there was simply nobody looking.

And there is one signal that appears on only one side. Psychotic symptoms, meaning losing contact with reality, can occur during severe mood episodes and are not part of the ADHD picture. This cannot be read backwards: the same review that says so reports cases of stimulant-induced psychotic or manic symptoms, so in someone with ADHD on treatment they may come from the medication rather than from the diagnosis. It is uncommon, and in that review 92% of cases were brief, with recovery between two and seven days once the doctor lowered or stopped the drug. They are not exclusive to bipolar disorder either: they occur in other conditions. If this is happening to you, it is not a data point for classifying yourself: seek help today, and if you cannot, call 113, option 5, or 106. Do not stop anything on your own in the meantime.

Why telling ADHD and bipolar apart changes the treatment

It matters more than it seems, for a concrete reason: when both conditions coexist, the Canadian and international guideline recommends treating mood symptoms first with mood stabilisers or atypical antipsychotics, and only then considering treatment for ADHD. Unstabilised bipolar disorder looks like ADHD, because it produces mood swings, impulsivity, hyperactivity and inattention.

And the order is not a technicality. As reported by the European consensus and a later review, in a Swedish registry study of 2,307 adults who already had a bipolar diagnosis, those who received methylphenidate without a mood stabiliser had more manic episodes, mostly within the first three months of starting the medication; among those who were also on one, the risk did not rise. It is worth reading that finding carefully: since everyone already had the diagnosis, what separated the two groups was not getting the diagnosis right, but whether or not they were on a mood stabiliser. And it does not mean treatment should be avoided: the European consensus recommends treating ADHD with stimulants in people with bipolar disorder, as long as they are also taking a mood stabiliser.

None of this is a recommendation for anyone, and least of all a reason to stop something. If you are on treatment and something does not feel right, that is a conversation with your doctor. Do not start, change or stop any treatment on your own, whether it is a stimulant, an antidepressant or a mood stabiliser: stopping abruptly can trigger a relapse, withdrawal symptoms or a rebound of whatever was being controlled, and that turns a question into a problem.

And the other half is worth saying, because an article that only talks about risks leaves a false impression: with the right diagnosis, adult ADHD does have treatments with evidence behind them. A review of 113 trials with 14,887 adults found that stimulants and atomoxetine were the only interventions with evidence of reducing core symptoms in the short term. The same authors warn that this improvement did not extend to other outcomes, such as quality of life, and that the long-term effect is under-researched. In other words: there is something to treat with, and it is not a promise that everything gets fixed.

People with ADHD also get labelled bipolar

It would be convenient to think the confusion always runs one way, the “I thought it was ADHD and it was bipolar disorder” way. It does not.

An international guideline notes that, according to some reports, bipolar disorder also gets overdiagnosed at times, and that people with ADHD, with borderline personality disorder or with substance use are sometimes given that label by mistake. And in the case of girls and women with ADHD, a British guideline notes they maybe more likely to receive an incorrect diagnosis of another mental health or neurodevelopmental condition; it is worth knowing that this recommendation rests on the committee’s consensus rather than on formal evidence, as the guideline itself makes clear. A single-author review published in Lancet Psychiatry, focused on childhood but explicitly extended to adulthood, points the same way: there is growing evidence that diagnostic overshadowing from anxiety, depression and other mental disorders could influence whether ADHD is recognised in time in women, something that also weighs on late diagnosis in women.

If you have been carrying a label for years that never quite fitted, that is also a reason to be reassessed.

What this article about ADHD and bipolar cannot tell you

Recognising yourself in some of the above does not mean your diagnosis is wrong. Bipolar disorder is uncommon: type I affects around 1% of adults, and type II, which involves hypomania and depression rather than mania, around 0.4%. Most people who get distracted, whose mood shifts, or who have good and bad weeks do not have it. To give a sense of scale: across eleven studies of adults, ADHD prevalence would be around 5%, although the author himself asks for caution because in adults it was measured mostly by self-report. The figures are not strictly comparable, but they serve the point that matters here: ADHD is considerably more common than bipolar disorder.

There is also a fourth possibility this article has not named: that it is neither of the two, but anxiety, a depressive condition, substance use, a sleep problem, a thyroid issue, or the consequences of something you lived through. That last one is not a rhetorical addition: a review pooling studies of children and adults describes ADHD and posttraumatic stress disorder as often comorbid and sharing a common core of symptoms. And when ADHD is there, it rarely comes alone: around 70% of adults who have it also have another mental health condition.

One clarification about what an episode looks like from the inside, because the article may have given an incomplete picture: it is not always euphoria and productivity. The diagnostic criteria allow for the mood of a manic episode to be irritable rather than elevated, in which case one additional symptom is required, and also for presentations with mixed features, where the speeding up mixes with feeling terrible. If that was your experience, you are not ruled out for not having felt euphoric.

If your diagnosis has fitted and your treatment works, nothing you read here contradicts it. This is for the opposite situation: when the label never quite explained what happens to you.

How is it diagnosed, ADHD or bipolar disorder?

Not with a test: it is done by a specialist, through a clinical assessment that looks at your whole history. And I understand that may not be the answer you were after if you got here wanting to settle the question today.

ADHD should only be diagnosed by a specialist with training and expertise in diagnosing it, and no rating scale is enough on its own. The British guideline even advises against using questionnaires in primary care to identify bipolar disorder in adults.

As for what needs ruling out, it runs both ways. Before calling it ADHD it is worth ruling out that another psychiatric diagnosis explains it, even though they can coexist. And when what is being assessed is bipolar disorder, ADHD is one of the diagnoses the specialist must consider, along with physical conditions such as thyroid problems.

What does answer the question is an assessment that looks at your full history, not just the past year: when each thing started, whether there were periods different from the rest, how you slept during those periods, what others noticed, and what your family says about your childhood. That does not fit in a form, and sometimes it does not close in a single appointment either.

It helps a great deal to arrive with three things ready: a written timeline of your good and bad stretches, someone who has known you for years, and the list of what you have taken and what happened with each.

If you are going through a crisis
There are situations where booking an appointment is not the right step, and getting help today is: thoughts of harming yourself, several days sleeping very little without feeling tired, losing contact with reality, or risky behaviour that is out of character.
In Peru you can call 113, option 5, which is free and staffed 24 hours, or 106 (SAMU) in an emergency. These lines are staffed in Spanish. If you need support in English, go to your nearest emergency service. If you cannot make the call yourself, ask someone to call with you, or go directly to an emergency department. If the person in that situation is someone else, do not leave them alone and seek help on their behalf.
And outside an emergency: an assessment does not have to be private. The Ministry of Health runs community mental health centres across the country, alongside the mental health services of hospitals and primary care posts.

When to ask for an ADHD or bipolar assessment

It is worth asking for an assessment if you recognise yourself in any of these situations:

Someone in your immediate family has a bipolar diagnosis, was hospitalised because of their mood, or took lithium.
There were stretches of four days or more when other people noticed you were different: more sped up, talking more, sleeping less, caught up in several projects or spending more than usual.
Or similar stretches, but experienced as irritability and a short fuse rather than as euphoria.
You were diagnosed with depression and there were periods when you slept far less without feeling tired.
After starting an antidepressant, a stretch of euphoria or speeding up appeared. If that is your case, seek advice soon, but do not stop the antidepressant on your own.
You were diagnosed with depression and, on top of that, the episodes were brief and highly recurrent, or began before the age of 25.
You have an ADHD diagnosis, or reached that conclusion on your own, and there are periods of your life that were clearly different from the rest.

And if you recognise yourself in none of them but something still does not add up, raise it with your usual doctor: not everything that fails to fit this list is ADHD or bipolar disorder.

If you have spent a while wondering whether what you have is ADHD, bipolar disorder or both, an assessment that looks at your full history is the place to start. In my practice in Miraflores (Lima) and by video consultation I assess adult ADHD and bipolar disorder with an evidence-based approach. I see patients in Spanish and English and provide receipts for insurance reimbursement.

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Frequently asked questions

How do you tell ADHD apart from bipolar disorder?
By the pattern over time, not by how intense the mood changes feel. ADHD is a steady trait that goes back to childhood or early adolescence, with mood changes that are brief, usually triggered by something during the day, and back to normal within a few hours. Bipolar disorder comes in episodes: four days or more for hypomania, seven or more for mania, with a return to baseline in between. Other signals help: during a manic phase the need for sleep drops, often without any physical discomfort, and psychotic symptoms can appear in severe mood episodes but are not part of ADHD, although in someone on treatment they can come from the medication. No single signal is enough on its own, and the diagnosis is made by a specialist.

Does having mood changes several times a day mean bipolar disorder?
On its own, it does not tell you. In a small study of sixty adult women, with a design that left the ADHD group off their medication and the bipolar group in a stable phase, emotional instability was elevated in both, without separating them. What does tell you something is duration: changes lasting hours, triggered by something specific, look more like what happens in ADHD; a mood episode lasts days, not minutes. And what helps most is looking back at the worst episode in the past, rather than at how you feel this week. That conclusion, in any case, comes from an assessment, not from reading.

I have had a diagnosis for years and my treatment works. Should I question it?
If it fits and it works, no. This article is not about revisiting diagnoses that are going well. It is for the opposite situation: when the label never quite explained what happens to you, when there were periods of your life nobody asked about, or when treatment never quite worked.

I took an online ADHD test and it came out positive. Is that enough to diagnose me?
It is a good reason to book an appointment, and nothing more. An ADHD diagnosis must be made by a specialist with specific training, and it is not made on a rating scale alone. What a test cannot see is exactly what settles the diagnosis: when each symptom started, whether there were periods clearly different from the rest of your life, what the people around you noticed, and what your childhood history says.

This article is for information only and does not replace an individual medical evaluation. Do not start, change or stop any treatment without consulting your doctor.