A 70 mg dose of Vyvanse typically provides 10 to 14 hours of symptom control, making it one of the longest-lasting ADHD medications available. That range isn’t fixed, though. Your body weight, metabolism, stomach contents, and individual brain chemistry all shift the window. Here’s what the timeline actually looks like and why the duration can vary.
The Typical Timeline for 70 mg
Vyvanse is a prodrug, meaning the capsule you swallow isn’t the active medication yet. Your body has to convert it first. Enzymes inside red blood cells break the drug apart, gradually releasing the active stimulant into your bloodstream. This built-in conversion step is why Vyvanse ramps up more slowly and lasts longer than immediate-release stimulants.
Most people notice the first effects around 90 minutes after taking it. The active component reaches its peak concentration in your blood roughly 4 to 4.5 hours after you swallow the dose. From there, it holds relatively steady before tapering off. In clinical trials submitted to the FDA, Vyvanse produced statistically significant improvements in attention from 2 hours post-dose all the way out to 14 hours in adults. In pediatric studies, measurable effects lasted from 2 to 12 or 13 hours post-dose.
So if you take your 70 mg capsule at 7 a.m., you can reasonably expect it to start working by 8:30 a.m., hit its stride around 11 a.m. to noon, and begin fading somewhere between 5 p.m. and 9 p.m. depending on your metabolism.
Why 70 mg Doesn’t Necessarily Last Longer Than Lower Doses
A common assumption is that the highest available dose (70 mg) will last significantly longer than a 30 mg or 50 mg dose. In practice, higher doses primarily increase the intensity of the effect rather than dramatically extending its duration. The conversion process in your red blood cells works at roughly the same pace regardless of dose. You get a higher peak with 70 mg, which can make the tail end of the effect feel slightly longer since it takes more time for a higher concentration to drop below your therapeutic threshold. But the difference in duration between doses is modest, usually an hour or two at most.
What Happens as It Wears Off
The active stimulant released from Vyvanse has a half-life of about 12 hours, meaning half the drug is still in your system 12 hours after peak levels. But “still in your system” and “still working” are different things. Most people feel the therapeutic effects fade well before the drug fully clears, because the blood concentration drops below the level needed to meaningfully control symptoms.
As the medication tapers in the afternoon or early evening, many people experience what’s sometimes called a “crash.” This can show up as irritability, fatigue, anxiety, or simply the return of your baseline ADHD symptoms. It tends to be more noticeable with higher doses like 70 mg because the drop from peak to sub-therapeutic levels is steeper. The crash isn’t dangerous, but it can feel abrupt if you’ve had smooth focus all day and suddenly notice it slipping away.
Eating a protein-rich meal a few hours before the expected wear-off, staying hydrated, and avoiding caffeine late in the day can soften the transition. Some people find that light exercise in the late afternoon helps bridge the gap.
Factors That Shorten or Extend Duration
Several things can shift how long your 70 mg dose holds:
- Stomach acidity. Acidic foods and drinks (citrus juice, soda, vitamin C supplements) taken around the same time as your dose can reduce absorption and shorten the effective window. Alkaline conditions do the opposite.
- Body weight and composition. A larger body distributes the drug across more tissue, which can dilute the effect and make it wear off sooner.
- Metabolic rate. People who metabolize drugs quickly, often younger adults or those who exercise heavily, tend to burn through Vyvanse faster.
- Sleep and food. Poor sleep the night before can make the medication feel weaker and shorter-lived. Skipping breakfast doesn’t affect absorption much, but eating a balanced meal can smooth out the release curve.
- Tolerance. Over months or years, your brain can adapt to the medication, making the same dose feel like it wears off earlier than it used to.
How Long It Stays Detectable
Even after you stop feeling the effects, Vyvanse’s active component lingers in your body. With a 12-hour half-life, it takes roughly 2 to 3 days for the drug to fully clear your bloodstream. Standard urine drug screens can detect amphetamines for about 2 to 4 days after your last dose, depending on hydration and metabolism. This is worth knowing if you’re facing a workplace drug test: a valid prescription resolves any positive result, but timing matters if you need to provide documentation.
When 70 mg Feels Too Short
If your 70 mg dose consistently fades before the end of your workday or school day, that’s a common and solvable problem. Since 70 mg is the maximum approved dose of Vyvanse, the solution isn’t simply taking more. Instead, prescribers often add a small immediate-release stimulant in the afternoon to cover the last few hours. Another option is adjusting the timing of your dose: taking it 30 to 60 minutes earlier can shift the entire curve so coverage extends further into the evening.
Tracking your pattern for a week or two helps pin down exactly when the drop-off happens. Note the time you take your dose, when you first feel it working, and when you notice it fading. That data gives your prescriber something concrete to work with rather than relying on a rough guess.