How Long Do Headaches After a COVID Vaccine Last?

Most headaches triggered by a COVID vaccine resolve within a day. In studies tracking the timing closely, half of recipients with post-vaccine headache reported it lasting under six hours, and about 80 percent were headache-free within roughly 22 hours. A meaningful minority, around a quarter of those affected, experience headaches stretching past three days, and a much smaller group develops symptoms that linger for weeks. The typical experience is short-lived discomfort that starts within the first day after the shot and fades without treatment, but there are enough variables at play that the story is more interesting than “a day or two.”

When the Headache Starts and How Long It Lasts

Post-vaccine headaches usually arrive quickly. A large multicenter study of people receiving the Pfizer-BioNTech mRNA vaccine found the average time between the shot and headache onset was about 18 hours. More than half of participants felt the headache within 10 hours, and 80 percent had it by the 24-hour mark. Fewer than one in ten reported a headache that only began after two full days had passed.¹ A separate analysis of healthcare workers vaccinated with various COVID vaccines found median onset at about one day post-vaccination, consistent with the broader pattern.²

Duration is where the numbers get reassuring for most people. In the multicenter BNT162b2 study, the average headache duration was about 14 hours, but the average was pulled up by a small number of long-lasting cases. The median was only about six hours, meaning the typical person’s headache resolved well before a full day had gone by. Only about 10 percent of those with headaches still had them past 36 hours.¹ Among the healthcare workers in the other study, roughly three-quarters saw their headache clear in under three days, and close to half were done with it in under 12 hours.²

First Dose Versus Second and Booster Doses

Headache is more common after the second dose. U.S. surveillance data from the first six months of the vaccination program found that about 27 percent of recipients reported headache within a week of the first dose, compared with roughly 46 percent after the second dose.³ A cross-sectional study found the same trend: headache incidence roughly doubled from the first to the second dose.⁴

When it comes to booster shots, the picture is mixed. In one study that compared side-effect duration between the second and third doses, about half of participants reported that side effects lasted longer after the booster than after the second dose, while about a quarter said the opposite. Joint pain appeared to drive much of the longer-lasting discomfort after the booster, rather than headache specifically.⁵ In practical terms, you should expect the second dose to be worse for headaches than the first. Whether the booster adds further intensity depends on the individual.

Do Different Vaccine Types Cause Different Headaches

Adenoviral vector vaccines (such as AstraZeneca’s Vaxzevria and Johnson & Johnson’s Janssen) generally triggered headaches more often than mRNA vaccines, and inactivated-virus vaccines triggered them the least. One survey found headache in about 54 percent of adenoviral vector recipients, 48 percent of mRNA recipients, and about 35 percent of those who received an inactivated vaccine.⁶ A German study of healthcare workers reported even steeper differences, with roughly three-quarters of adenoviral vector recipients experiencing headache or fatigue compared with just under half of mRNA recipients.⁷

Interestingly, while adenoviral vector vaccines seemed to cause headaches sooner after the shot, the actual duration of the headache did not differ significantly between vaccine types. A study comparing multiple platforms found no meaningful variance in how long the headache lasted regardless of which vaccine was used, though the Moderna (Spikevax) vaccine did produce headaches of significantly greater intensity than some of the others.⁸

A large meta-analysis put a useful frame on this: regardless of vaccine platform, vaccination roughly doubled the risk of developing headache within seven days compared with placebo. The researchers interpreted this lack of difference between vaccine types as evidence that the headache reflects a general immune system reaction rather than something specific to the vaccine technology itself.⁹ Your immune system revving up is what produces the headache, and that process is broadly similar regardless of how the vaccine delivers its instructions.

Who Is More Likely to Get a Longer or Worse Headache

Two demographic patterns show up consistently. Women report post-vaccine headaches at significantly higher rates than men, and their headaches tend to last longer. Younger adults are also hit harder than older adults. One study found that about two-thirds of female participants under 65 reported headache after vaccination, compared with roughly a quarter of those 65 and older.⁵ This aligns with the broader pattern across many vaccines: stronger reactogenicity in women and younger people, likely because their immune systems produce a more vigorous inflammatory response to the vaccine.

If you have a history of migraine, expect more. People with pre-existing migraine were nearly twice as likely to develop a headache after vaccination compared with those without a headache history, and those with other non-migraine headache disorders had similarly elevated rates.⁴ The headaches they experienced also lasted longer on average, about 16.5 hours versus 13 hours in people without a primary headache disorder, and were rated as more intense.¹

Beyond the immediate post-vaccine headache, a longitudinal study of migraine patients found an increase in monthly migraine days during the first month after vaccination, with about one additional migraine day and roughly 1.5 additional headache days compared to the pre-vaccination baseline.¹⁰ That temporary bump settled afterward, but it is worth knowing about if you track your migraine frequency closely.

Managing the Pain

Standard over-the-counter pain relievers work well for post-vaccine headache. The more practical question for many people is whether taking something preemptively could blunt the immune response. The best-studied scenario involves acetaminophen (paracetamol). In a phase 1/2 trial of the AstraZeneca vaccine, participants who took prophylactic acetaminophen before and in the first two days after vaccination saw a significant reduction in headache, with roughly half the odds of developing one compared with those who did not take acetaminophen. The key finding: immunogenicity was not affected, meaning the vaccine still did its job.¹¹

The evidence on ibuprofen and other anti-inflammatory drugs in this specific context is thinner, but general guidance from public health agencies has been to use whichever over-the-counter pain reliever you normally tolerate. Rest, hydration, and a cool compress are reasonable additions, though they have not been studied in controlled trials for this purpose. The main takeaway is that treating the headache does not appear to compromise the protection the vaccine gives you.

When a Post-Vaccine Headache Deserves Attention

The vast majority of post-vaccine headaches are benign and self-limiting. They would technically meet the international diagnostic criteria for headache attributed to exposure to a substance, though vaccines are not currently listed among recognized triggers in the formal classification system.¹² The important thing is to recognize the unusual patterns that should prompt a call to your doctor.

Timing is the biggest red flag. A headache that begins more than a week after vaccination, particularly four to fourteen days later, looks very different from the typical next-day headache and was flagged as a potential signal for vaccine-induced cerebral venous thrombosis (CVT). In a review of CVT cases following adenoviral vector vaccines, the median time from vaccination to headache onset was eight days.¹³ CVT is extremely rare, but the headache it causes is severe, persistent, and often accompanied by other neurological symptoms like visual disturbances or confusion. A headache that arrives a week or more after the shot and keeps getting worse is not a normal vaccine side effect.

A smaller number of people develop headaches that persist for a month or longer. A prospective follow-up study identified two distinct clusters among patients whose headaches lasted well beyond the usual window. One group had features resembling migraine: throbbing, frontal pain with nausea, light sensitivity, and sound sensitivity, mostly in people who already had a history of primary headache disorders. The second cluster was characterized by a pressing or stabbing quality and headache duration stretching beyond a month, sometimes in people without any headache history.¹⁴ These persistent cases are uncommon but can be disruptive, and they are worth discussing with a neurologist if the headache does not improve within a few weeks.

How Much of It Is the Nocebo Effect

This is the part of the story that makes researchers uneasy and patients defensive, but the data are hard to ignore. In clinical trials, a substantial fraction of people who received a saline placebo also reported headaches. A systematic review and meta-analysis of adverse events in placebo arms of COVID vaccine trials found that headache was among the most commonly reported side effects even when the injection contained no active vaccine at all. These so-called nocebo responses are thought to stem from anxiety, expectation of side effects, and the human tendency to attribute normal background symptoms to a recent medical event.¹⁵

A study of migraine patients who reported worsening of their condition after vaccination found that the strongest predictor of perceived worsening was simply being worried that it would happen. When researchers measured actual headache frequency in the month before and the month after vaccination, they found no significant difference, even among those who said their migraines had gotten worse. The worry itself appeared to shape the experience more than any underlying biological change.¹⁶

This does not mean post-vaccine headaches are imaginary. Real inflammatory processes drive the typical immune-mediated headache, and the doubled risk seen in active-vaccine arms versus placebo arms confirms that. But some portion of what people attribute to the vaccine, particularly headaches that show up late or that feel like an escalation of a pre-existing pattern, may have more to do with expectation than pharmacology. It is a finding worth being honest about, because understanding it can actually reduce your anxiety before the next shot.

Adolescents and Post-Vaccine Headache

Younger teenagers are not spared. In a Danish retrospective study, vaccinated 12- to 14-year-olds had roughly double the odds of reporting headache after the second dose compared with unvaccinated peers. Among 15- to 19-year-olds, the odds were elevated by about two-thirds.¹⁷ The general trajectory mirrors adults: most of these headaches are brief and resolve on their own.

Persistent cases in adolescents exist but are extremely rare. A case report described a teenager who developed new daily persistent headache starting on the day of the second Pfizer dose. The headaches were continuous, punctuated by more severe throbbing episodes several times a day, and did not improve with standard rescue medications.¹⁸ New daily persistent headache is a recognized clinical entity that can be triggered by various infections and immunological events. A single case report is not evidence of a widespread risk, but it does serve as a reminder that adolescents with headaches lasting more than a couple of weeks after vaccination should be evaluated, just as they would for any other new persistent headache.

Getting a COVID Vaccine and a Flu Shot at the Same Time

A practical question for many people headed into fall: does getting a flu shot alongside the COVID booster make the headache worse or last longer? A randomized study compared three groups: COVID vaccine alone, flu vaccine alone, and both at once. Among those who received only the COVID vaccine, about three-quarters reported no headache at all, and the vast majority of those who did had symptoms resolve within 48 hours. In the group that got both shots simultaneously, the overall rate of systemic symptoms was statistically similar to the COVID-only group.¹⁹

A slightly higher percentage of the co-administration group had symptoms lasting beyond 72 hours compared with the COVID-only group, but the numbers were small (under 5 percent in both groups saw symptoms past that point). The practical lesson is that getting both vaccines in one visit is unlikely to turn a manageable headache into a prolonged ordeal, and it saves you a second trip and a second round of the immune response altogether.

Prior COVID Infection and Headache Risk

People who had already been infected with SARS-CoV-2 before getting vaccinated showed a pattern broadly similar to the general population when it came to headache timing. In a study of healthcare workers with a history of COVID infection, the mean time between vaccination and headache onset was about 27 hours, with over 80 percent developing the headache within 24 hours. The headache reached peak intensity within about nine hours of its onset.²⁰ Early in the pandemic, there was concern that previously infected individuals might experience more severe reactogenicity from vaccination, and some did report stronger short-term side effects. But the headache timeline itself was not dramatically different from what studies found in uninfected populations, and the headache remained a short-lived event for most.