NSee your experience clearly. Describe it accurately.
This guide is written to be the clearest patient guide to HG symptoms you can find. If you are trying to decide whether what you are feeling is normal, start here. Read it with a highlighter, or read it to a partner. The goal is simple: to help you see your own experience clearly and describe it accurately to the people who can help.
Why This Matters
Most pregnancy nausea is safe to wait out. HG is not. The difference between the two determines whether waiting is wise or dangerous — and women with HG are routinely told to wait too long. Learning to see the difference clearly, and to describe it accurately, is often the single step that gets treatment started. That is why this guide exists: not to alarm you, but to give you the clarity and the words that get you believed.
Definition
Hyperemesis Gravidarum is severe, persistent nausea and vomiting during pregnancy that interferes with your ability to eat, drink, and function, and that can lead to dehydration, weight loss, electrolyte imbalance, and malnutrition. It is the most severe end of the spectrum of nausea and vomiting of pregnancy. Where ordinary morning sickness is a nuisance, HG is a medical condition that often requires treatment and sometimes hospital care.
Doctors do not rely on one single test to diagnose HG. They look at the whole picture: how often you are vomiting, whether you can keep anything down, how much weight you have lost, whether you are dehydrated, and what your lab work shows. This is why describing your symptoms accurately matters so much.
Morning sickness versus HG: a side-by-side comparison
No single row makes the diagnosis. It is the overall pattern that matters, and only your healthcare provider can confirm HG. Use this to help you notice which column your experience falls into.
Symptoms
HG is more than vomiting. It affects the whole body and, over time, nearly every part of daily life. Below is a thorough look at the symptoms women with HG experience, including several that are rarely discussed but deeply important.
Physical symptoms
The core physical symptoms of HG usually include severe nausea that does not let up, frequent vomiting, retching or dry heaving, and an intense sensitivity to smells, motion, and sometimes even the sight of food. Many women also produce excessive saliva, a symptom called ptyalism, which can itself trigger nausea. These symptoms feed one another, which is part of why HG can escalate so quickly.
Weight loss
Losing weight in early pregnancy is one of the clearest warning signs that nausea and vomiting have crossed into HG. Research often uses a loss of 5 percent or more of pre-pregnancy body weight as a marker of severity. If you are losing weight while pregnant, tell your provider promptly. Weight loss is not something to wait out.
Malnutrition
When food will not stay down for days or weeks, the body is deprived of the nutrients and calories it needs. This can lead to deficiencies in vitamins and minerals, including thiamine (vitamin B1), which is particularly important. Severe, prolonged vomiting with low thiamine can, in rare cases, lead to a serious neurological condition, which is one reason providers may give vitamin supplementation. Malnutrition also worsens fatigue and slows recovery, so restoring nutrition is a central goal of HG care.
Dehydration
Dehydration is one of the most common and most dangerous consequences of HG. When you cannot keep fluids down, your body loses water faster than it can replace it. Signs of dehydration include very dark urine, urinating little or not at all, a dry mouth, extreme thirst, dizziness, a racing heart, and feeling faint when you stand. Dehydration is a frequent reason women with HG need IV fluids or hospital care, and it is a signal to seek help quickly.
Electrolyte imbalance
Repeated vomiting flushes out important minerals called electrolytes, such as sodium, potassium, and chloride, that your body needs to keep your heart, muscles, and nerves working properly. An imbalance can cause muscle weakness, cramps, an irregular heartbeat, confusion, and extreme fatigue. Providers check electrolytes with blood tests and can correct them, often through IV fluids. This is one of the medical reasons HG is taken seriously rather than simply managed at home.
Rapid heart rate
A fast or pounding heartbeat can be a sign of dehydration and electrolyte imbalance. If your heart is racing, especially along with dizziness, weakness, or fainting, it is a signal that your body needs fluids and medical evaluation. Do not dismiss it.
Weakness
Profound weakness is common in HG and usually reflects the combined effect of dehydration, low nutrition, electrolyte imbalance, and lost sleep. Some women describe not having the strength to stand in the shower or lift a glass of water. This is a real physical consequence of the condition, not a lack of willpower.
Fatigue
Fatigue is one of the most disabling and least discussed parts of HG, which is exactly why THON insists on covering it. The exhaustion of HG is not ordinary tiredness. It comes from several sources at once: the body working hard in early pregnancy, constant nausea and vomiting, dehydration, poor nutrition, disrupted sleep, and the sheer mental toll of feeling sick around the clock.
Many women say the fatigue is as hard to bear as the vomiting. It can make it impossible to work, care for children, or do basic tasks. If you are experiencing this, you are not lazy and you are not failing. Deep fatigue is a recognized part of HG, and it deserves acknowledgment and support. Rest is not indulgence here; it is part of coping with an illness.
Dizziness and fainting
Dizziness, lightheadedness, and fainting can result from dehydration, low blood pressure, low blood sugar from not eating, and electrolyte imbalance. Feeling faint when you stand up is a common sign that you need fluids. Actually fainting, or nearly fainting, is a reason to seek care, both because of what it signals and because of the risk of falling and injury.
Oral health
Oral health is one of the most overlooked aspects of HG, and protecting your teeth is simple once you know how. Repeated vomiting bathes your teeth in stomach acid. Over time, this acid wears away tooth enamel, the hard protective outer layer, which does not grow back. It can lead to sensitivity, cavities, and lasting damage.
- Rinse your mouth right after vomiting with plain water, or with water mixed with a small amount of baking soda (about one teaspoon in a cup of water) to neutralize the acid.
- Wait at least 30 minutes before brushing, so your enamel can re-harden.
- Use a soft toothbrush and a fluoride toothpaste.
- Smearing a little fluoride toothpaste on your teeth without rinsing it off at night can add extra protection.
- Stay as hydrated as you can, and tell your dentist you are pregnant and have HG so they can help protect your teeth.
Sleep disruption
HG frequently wrecks sleep. Nausea does not respect nighttime, and many women wake repeatedly to vomit or lie awake feeling sick. Poor sleep then worsens fatigue, nausea, and mood, creating a difficult cycle. Broken sleep is a genuine part of the HG burden, and it is worth mentioning to your provider, because improving nausea control can sometimes improve sleep as well.
Difficulty working
Many women with HG cannot work, or can only work with great difficulty. Constant nausea, vomiting, exhaustion, and sensitivity to smells make most jobs extremely hard. This can bring real worry about income, job security, and how much to tell an employer. These concerns are valid. Future volumes of the HG Care Hub will address workplace rights and accommodations in depth. For now, know that needing time off for HG is a legitimate medical need, and your provider can document it.
Difficulty caring for children
For women who already have children, HG can make parenting feel impossible. Lifting a toddler, preparing meals, or simply staying upright can be beyond reach. Guilt is common and understandable, but it is misplaced. You are managing a serious illness. Accepting help from family, friends, or community is wise, not weak, and asking for it is an act of care for your children, not a failure toward them.
Difficulty functioning
Taken together, these symptoms can strip away a woman's ability to do almost anything: to eat, to work, to parent, to socialize, to care for herself. This loss of normal functioning is one of the defining features that separates HG from morning sickness, and it is one of the clearest things to describe to your provider. If HG is taking over your life, say exactly that.
Mental health
HG affects the mind as well as the body, and this is not a weakness or a personal failing. Being severely ill for weeks or months, unable to eat, exhausted, and sometimes disbelieved, takes a real emotional toll. Women with HG have higher rates of depression and anxiety, and some experience symptoms consistent with trauma, both during and after pregnancy.
Feelings of sadness, hopelessness, dread, isolation, or even resentment toward the pregnancy do not make you a bad mother. They are understandable human responses to a very hard experience. Mental health is a core part of HG care, not an afterthought. If you are struggling emotionally, please tell your provider. Support is available, and it works. If you ever have thoughts of harming yourself, seek help immediately: call or text 988 in the United States, or go to the nearest emergency department.
What This May Feel Like
Beyond the clinical symptoms above, these are experiences women with HG commonly describe. They are lived experience, not diagnostic criteria — but if you recognize yourself here, take it seriously and say so to your provider.
These reflect commonly reported patient experiences — not medical conclusions. But they are precisely the kind of plain description that helps a care team understand how serious things have become.
Family history and risk factors
You are more likely to develop HG if certain factors are present. Having these does not guarantee HG, and not having them does not rule it out, but they help explain why HG happens and can prepare you and your care team.
- A personal history of HG. If you had HG in a previous pregnancy, your chance of it returning is higher.
- A family history of HG. HG runs in families. If your mother or sister had it, your risk is higher, which points to a genetic component.
- Carrying more than one baby. Twins or higher-order pregnancies raise the risk.
- A history of severe nausea from other causes, such as severe motion sickness or migraines.
- A molar pregnancy, an uncommon condition your provider screens for.
Learn About HG explains the science behind these risk factors, including the hormone GDF15 and the genetics that help explain why HG clusters in families.
When symptoms become dangerous
Most of the time, HG is managed with medication, fluids, and close follow-up. But certain signs mean the situation has become urgent. Knowing them protects you, and it helps partners and family members know when to act.
- Vomiting several times a day and struggling to keep fluids down
- Losing weight
- Urinating less than usual, or urine that is dark
- Feeling dizzy, weak, or lightheaded
- Being unable to work or care for yourself or your family
- Your current anti-nausea plan is no longer working
- Not been able to keep any fluids down for 12 to 24 hours
- Signs of significant dehydration: no urination for 8 hours or more, severe dizziness, fainting, or a racing heart
- Vomiting blood, or vomit that looks like coffee grounds
- Severe abdominal pain
- Vaginal bleeding
- A fever
- Confusion, severe weakness, vision changes, or trouble walking or speaking
Common myths about HG
Misinformation about HG causes real harm, because it delays care and makes women feel unheard. Here are some of the most damaging myths, and the truth.
Frequently asked questions
What should I do now?
Your Next Conversation
Preparing for an appointment can feel overwhelming, especially when you are not feeling well. These conversation starters can help you have a more informed discussion with your healthcare provider. Depending on what you learn together, THON can help guide you to additional resources throughout your HG journey.
Receiving an accurate diagnosis is one of the most important first steps toward appropriate treatment and preventing complications. Many women are told this is normal for weeks before anyone looks closely.
Treatment in HG is stepped, and early intervention changes outcomes. Asking about the next step now means you do not have to start the conversation over when the first approach stops working.
Dehydration is what turns HG from exhausting into dangerous, and it is measurable. A monitoring plan is what allows it to be caught before it requires emergency care.
Knowing the threshold in advance removes the hardest decision from the hardest moment. Going early for IV hydration is almost always better than going late.
Repeated vomiting damages tooth enamel, and dental consequences after HG are common and often costly. A few habits now — and brushing at the right time — prevent much of it.
Anxiety, low mood, and traumatic stress following HG are well documented and treatable. Saying it out loud in the appointment is usually what makes support happen.
Written documentation is what turns a request for workplace adjustments into an arrangement that holds. One proportionate note usually covers the whole pregnancy.
Companion resources
From the THON Companion Series™ — each pairs with this guide. All 13 print-ready resources live in the THON Resource Center™.
Clinical references
Clinical guidance on this page draws on the American College of Obstetricians and Gynecologists (ACOG), the Society for Maternal-Fetal Medicine (SMFM), the HER Foundation, the National Institutes of Health (NIH), and peer-reviewed research. Full citations appear in the References section of the THON HG Care Hub™ Launch Edition, Volume I.