A heightened sense of smell, clinically called hyperosmia, can result from hormonal changes, genetic wiring, neurological conditions, or even the structure of your brain. It’s not always a sign that something is wrong. Some people are naturally more sensitive to odors, while others develop increased smell sensitivity temporarily due to pregnancy, migraines, or hormonal shifts. Understanding the most likely cause depends on when the sensitivity started, whether it comes and goes, and what other symptoms accompany it.
Your Brain May Be Built for Stronger Smell
Some people are genuinely “super smellers,” scoring in the top 10% on standardized smell tests. Brain imaging research has found that these individuals have measurably more gray matter volume in two key areas: the insula, which processes sensory information and emotional responses, and the hippocampus, which handles memory. In super smellers, hippocampal volume directly correlated with olfactory test performance, meaning the larger these brain regions were, the better a person scored on smell identification and detection.
This suggests that for some people, a strong sense of smell is simply how their nervous system is wired. If you’ve always been more sensitive to odors than the people around you, your brain’s smell-processing regions may be physically larger and more active than average.
Genetics Shape What You Can Detect
Your DNA plays a surprisingly specific role in smell sensitivity. Humans carry around 400 different types of olfactory receptors, and genetic variation in these receptors determines which smells you pick up strongly and which ones barely register. One well-studied example involves a receptor called OR7D4, which detects androstenone, a compound found in cooked pork and in human sweat. People who carry two functional copies of this receptor gene are significantly more sensitive to androstenone and tend to find its smell unpleasant. Those with a nonfunctional variant can barely detect it at all.
This pattern repeats across many different odors. Your unique combination of receptor gene variants creates a smell “fingerprint” that makes you more or less sensitive to specific compounds. So if certain smells seem overwhelmingly strong to you but don’t bother anyone else in the room, genetics is a likely explanation.
Hormonal Changes and Pregnancy
Hormonal shifts are one of the most common triggers for a sudden increase in smell sensitivity, and pregnancy is the classic example. Many pregnant people report that smells become overpowering during the first trimester, often accompanied by nausea. The timing is important: these changes peak early in pregnancy, not later, which means estrogen alone probably isn’t the driver. Estrogen rises steadily throughout pregnancy and peaks near delivery, yet smell sensitivity is most intense in the first 12 weeks.
Researchers have pointed to human chorionic gonadotropin (hCG), the hormone measured by pregnancy tests, as a more likely candidate. hCG levels spike rapidly in early pregnancy and then taper off, matching the timeline of when smell changes are most pronounced. It’s also worth noting that smell sensitivity fluctuates across the menstrual cycle in some women, though the relationship between estrogen and these shifts is less straightforward than once believed. Women taking oral contraceptives show similar cyclical changes in smell thresholds despite having suppressed natural hormone fluctuations.
Migraines and Sensory Overload
If your sense of smell intensifies before or during headaches, migraines are a strong possibility. Heightened smell sensitivity is part of a broader pattern of sensory overload that accompanies migraine attacks, alongside light and sound sensitivity. About two out of three people with migraines without aura experience osmophobia, a condition where normal odors become intolerable during an attack. This symptom is distinctive enough that its presence can actually help distinguish migraines from tension headaches, where it doesn’t occur.
The mechanism involves sensitization of neurons along pain pathways. During a migraine, nerve cells become progressively more reactive, amplifying sensory signals from the head and neck. This sensitization can extend to the brain’s smell-processing centers, turning everyday odors into triggers that worsen nausea and pain. Some people notice heightened smell in the hours before a migraine fully develops, making it a useful early warning sign.
Adrenal Insufficiency and Other Medical Causes
Less commonly, a persistently heightened sense of smell can signal an underlying medical condition. Adrenal insufficiency (sometimes called Addison’s disease) has been linked to hyperosmia, along with a heightened sense of taste. In these cases, the adrenal glands don’t produce enough cortisol and other hormones, and the resulting hormonal imbalance appears to lower the threshold at which sensory signals register.
Certain autoimmune conditions affect smell, though typically in the opposite direction. Lupus and systemic sclerosis are associated with reduced smell function, not heightened sensitivity. Over half of lupus patients in one study showed measurable olfactory dysfunction compared to just 14% of healthy controls. This is worth noting because some autoimmune conditions can cause smell distortions that feel like heightened sensitivity even when objective testing shows the opposite.
When “Too Strong” Actually Means Something Else
Here’s a counterintuitive finding: many people who report hyperosmia actually perform worse on standardized smell tests, not better. A study at Johns Hopkins tested 148 patients who complained of hypersensitivity to smells using the University of Pennsylvania Smell Identification Test. Nearly 71% of those self-identified hyperosmics actually had measurable smell loss. Their average scores were significantly lower than people with no smell complaints.
What likely explains this is that the problem isn’t detection, it’s processing. When the brain’s ability to filter and interpret smells is disrupted, even faint odors can feel overwhelming or unpleasant. Conditions like nasal inflammation, sinus issues, or neurological changes can alter how your brain handles olfactory input, creating the sensation of being bombarded by smells even though your actual detection ability has decreased. If odors feel distorted or unusually offensive rather than simply stronger, this kind of processing issue may be at play.
Managing Heightened Smell Sensitivity
How you address a strong sense of smell depends entirely on the cause. If nasal polyps or chronic inflammation are involved, corticosteroids in the form of nasal sprays, rinses, or pills can reduce swelling and normalize smell processing. Newer biologic medications can also target the specific inflammatory pathways that damage olfactory tissue. In cases where polyps are the primary issue, minimally invasive surgery through the nostrils can remove them and open sinus passages without external incisions.
For migraine-related smell sensitivity, managing the migraines themselves is the most effective approach. Identifying and avoiding strong odors that trigger attacks can reduce their frequency. Keeping a diary of which smells precede your migraines helps narrow down specific triggers.
If your heightened smell is tied to pregnancy, it typically resolves after the first trimester or after delivery. In the meantime, practical strategies like keeping fresh air flowing, avoiding cooking smells that trigger nausea, and breathing through your mouth in overwhelming situations can help. For people who are naturally super smellers with no underlying condition, the sensitivity is a permanent trait. The focus shifts to managing your environment: choosing unscented products, ventilating your living space, and communicating with the people around you about scents that cause discomfort.