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Cimetidine is an acid reducer active ingredient available in over-the-counter (OTC) medicines that relieve or prevent heartburn symptoms associated with acid indigestion and sour stomach. Cimetidine is part of a group of acid reducers called histamine-2 antagonists, or H2 blockers.
Common Products
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- Tagamet®
- Store Brands (ex. Walmart’s “Equate” store brand or CVS Health store brand)
Dosing Information
Different types of products containing this active ingredient have different strengths. That’s why it is always important to read and follow the Drug Facts label. Most medicines warn against use of an active ingredient for longer than 7-10 days. Stop use and ask a doctor if symptoms persist.
A Note to Families:
While you might have seen media reports or social media posts on observational studies examining potential associations between acetaminophen use during pregnancy and neurodevelopmental outcomes (such as autism), it’s important to note that these studies do not demonstrate a causal relationship. In other words, there is currently no scientific evidence establishing that taking acetaminophen during pregnancy causes neurodevelopmental conditions.
Quick Facts:
1. Scientific and medical authorities around the world recognize acetaminophen as the only analgesic considered safe for use throughout an entire pregnancy when used according to the Drug Facts label.
2. There are no studies showing that acetaminophen use in children or during pregnancy causes autism.
3. Autism has many known risk factors, including genetics, but there is no clear, single cause.
4. Major health authorities like the FDA, CDC, and healthcare organizations such as the American College of Obstetricians and Gynecologists (ACOG) do not have warnings against acetaminophen use during pregnancy based on any known risk of autism and all recommend acetaminophen as the safest analgesic to use during pregnancy for short-term pain relief.
Frequently Asked Questions:
Why is acetaminophen used during pregnancy?
Scientific and medical authorities around the world recognize acetaminophen as the only pain reliever and fever reducer considered safe for use throughout an entire pregnancy when used according to the Drug Facts label, which specifically reminds pregnant women to always consult their healthcare provider before use. In fact, the American College of Obstetricians and Gynecologists (ACOG) states that: "Acetaminophen remains a safe, trusted option for pain relief during pregnancy.”
What is autism and does current science indicate what causes it?
Autism is a complex condition with many contributing factors, including genetic, environmental, and prenatal. Most scientists agree that the causes of autism are not simple, nor can they be traced back to one single factor like medication.
In fact, the Autism Science Foundation (ASF), a non-profit organization funding scientific autism research, specifically states that: it is disingenuous and misleading to boil autism's causes down to one simple thing," as there are hundreds of genes linked to autism in addition to other complex environmental factors.
Additionally, the most recent and rigorous research on this topic does not show a causal link to autism. The 2024 study published in the Journal of the American Medical Association (JAMA) analyzed nearly 2.5 million children using the gold-standard sibling comparison method, which controls for shared genetics and family environment, and found no association between acetaminophen use during pregnancy or infancy and neurodevelopmental issues such as autism.
In fact, the Autism Science Foundation (ASF), a non-profit organization funding scientific autism research, specifically states that: it is disingenuous and misleading to boil autism's causes down to one simple thing," as there are hundreds of genes linked to autism in addition to other complex environmental factors.
Additionally, the most recent and rigorous research on this topic does not show a causal link to autism. The 2024 study published in the Journal of the American Medical Association (JAMA) analyzed nearly 2.5 million children using the gold-standard sibling comparison method, which controls for shared genetics and family environment, and found no association between acetaminophen use during pregnancy or infancy and neurodevelopmental issues such as autism.
Why is it important to address fever during pregnancy?
High or long-lasting fevers can harm both the mother and baby and should be taken very seriously. Risks associated with leaving a fever untreated include birth defects, preterm labor, miscarriage, dehydration, or problems with the placenta, which significantly outweigh the risk of treatment.
What do regulatory authorities and major health organizations say?
The CDC and FDA agree acetaminophen is the safest analgesic to use during pregnancy for short-term pain relief, and recommend women to be cautious about overuse, which is why it is always recommended to follow the Drug Facts label and speak to your healthcare provider.
- CDC Yellow Book (Current as of April 23, 2025): “Acetaminophen remains the non-opioid analgesic of choice during pregnancy.”
- FDA’s Acetaminophen Page (Current as of August 14, 2025): “To date, FDA has not found clear evidence that appropriate use of acetaminophen during pregnancy causes adverse pregnancy, birth, neurobehavioral, or developmental outcomes.”
Additionally, the Society for Maternal-Fetal Health, a professional organization for obstetricians with subspecialty training in maternal-fetal medicine, stated on September 25, 2025 that it: "...continues to advise physicians and patients that acetaminophen is an appropriate medication to treat pain and fever during pregnancy…the weight of scientific evidence that acetaminophen use during pregnancy causes an increased risk for autism or ADHD is simply inconclusive…”
- CDC Yellow Book (Current as of April 23, 2025): “Acetaminophen remains the non-opioid analgesic of choice during pregnancy.”
- FDA’s Acetaminophen Page (Current as of August 14, 2025): “To date, FDA has not found clear evidence that appropriate use of acetaminophen during pregnancy causes adverse pregnancy, birth, neurobehavioral, or developmental outcomes.”
Additionally, the Society for Maternal-Fetal Health, a professional organization for obstetricians with subspecialty training in maternal-fetal medicine, stated on September 25, 2025 that it: "...continues to advise physicians and patients that acetaminophen is an appropriate medication to treat pain and fever during pregnancy…the weight of scientific evidence that acetaminophen use during pregnancy causes an increased risk for autism or ADHD is simply inconclusive…”
Is autism really on the rise?
When it comes to reports or claims that autism rates are higher than they were decades ago, the medical community’s ability to now better recognize and diagnose autism must be taken into consideration. Advances in medical knowledge, broader diagnostic criteria, and increased awareness among healthcare providers, educators, and parents mean that more cases are being identified today than in decades past. In other words, autism may not actually be “more common” than it once was; rather, we are better at detecting and recording it.
Is there a cure for autism?
No. There is no cure for autism. Autism is a complex neurodevelopmental condition influenced by many genetic and environmental factors. Treatments and supports focus on improving quality of life, communication, and daily functioning, not on “curing” autism.
What is leucovorin and why are there claims that it can “cure” autism?
Leucovorin (loo-ko-vor-in) is the prescription (Rx) form of folinic acid. It is officially approved by FDA for use in cancer therapy and as an antidote to certain medications. Some small studies have looked at leucovorinin individuals with cerebral folate deficiency (CFD). That’s why some families highlight it as promising. But it’s important to be clear: Leucovorin is not FDA-approved for autism or CFD. Its use for CFD is considered “off-label,” based on limited clinical evidence and physician judgement. On September 24, the FDA published a notice they intended to request that the drug sponsor submit an application to add information on CFD to the prescription drug label. Current research on its effectiveness in treating CFD is limited and preliminary. Calling it a “cure” for autism is misleading and not supported by robust, peer-reviewed evidence.
Safety Guide
Safety Guide
Cimetidine is approved by the U.S. Food and Drug Administration (FDA) and is safe and effective when used according to the Drug Facts label.
Ask a healthcare provider before use if:
- You are taking the asthma medicine theophylline.
- You are taking the blood-thinning drug warfarin.
- You are taking the seizure medicine phenytoin.
- You have had heartburn for more than three months.
- Your heartburn is accompanied by lightheadedness, sweating, or dizziness.
- You have kidney disease.
- You are experiencing chest or shoulder pain with shortness of breath; sweating; pain spreading to your arms, neck, or shoulders; or lightheadedness.
- You have frequent chest pain, wheezing, unexplained weight loss, nausea or vomiting, or stomach pain.
- You are pregnant or breastfeeding.
- Talk to a healthcare provider before giving an OTC containing cimetidine to a child under the age of 12.
Do not use if:
- You are allergic to cimetidine or other acid reducers.
- You have trouble or pain swallowing food, you are vomiting with blood, or you have bloody or black stools.
- You are currently using another acid reducer.
Stop use and ask a doctor if:
- Your heartburn continues or gets worse.
- Your stomach pain continues.
- You need to take the medicine for more than 14 days.
- You take too much. Immediately contact a healthcare provider or the poison control national helpline at 800.222.1222.
What are the side effects of cimetidine?
- Headache
- Dizziness
- Drowsiness
- Diarrhea
