For most people, an accidental double dose of amoxicillin is unlikely to cause serious harm. The most likely result is an upset stomach, nausea, or diarrhea. Do not take any more, and call your pharmacist or Poison Control at 1-800-222-1222 to ask what to do about your next dose.
Poison Control says an antibiotic overdose "is unlikely to result in serious symptoms." In 2023, US poison centers reported over 25,000 antibiotic exposures and 1 death. Amoxicillin also leaves your body fast. The FDA label for Amoxil tablets lists a half-life of 61.3 minutes. About 60% of a dose is excreted in the urine within 6 to 8 hours.
This article provides general information about medication management and is not a substitute for professional medical advice. Always consult your doctor or pharmacist before making changes to your medication schedule. Consult your doctor or pharmacist for advice specific to your medications.
How Much Is 2 Tablets of Amoxicillin 500 mg or 875 mg?
Start with the strength printed on your bottle. Two tablets of one strength is a very different amount than two of another, so have it in hand before you call.
To give those totals some scale, the table puts them next to doses that doctors already prescribe on purpose for other reasons. These are regimens chosen by a prescriber for a specific situation. They are not a safe limit for you.
| What you took | Total amoxicillin | A prescribed dose for comparison |
|---|---|---|
| Two 500 mg tablets or capsules | 1,000 mg | The Amoxil label lists 1 gram per dose in its H. pylori stomach infection regimens |
| Two 875 mg tablets | 1,750 mg | The American Heart Association lists a single 2 g oral dose before certain dental procedures for people at highest risk from a heart infection |
| Two Augmentin 875 mg/125 mg tablets | 1,750 mg amoxicillin plus 250 mg clavulanate | See the Augmentin section below. The clavulanate part changes the side effect picture |
The 1 gram figure comes from the Amoxil label, and the 2 g figure from the 2021 American Heart Association statement. Neither means your extra tablet was fine by definition. They show the range doctors work in. They do not tell you how you will feel.
How Long Does the Extra Amoxicillin Stay in Your System?
Not long. With a 61.3-minute half-life, the amount in your blood drops by half about every hour. The same label says a 500 mg dose reaches its peak blood level 1 to 2 hours after you take it.
Your kidneys do that clearing, which is why kidney disease is one of the things that changes this answer. For a wider look, see how long antibiotics stay in your system.
What to Do About Your Next Amoxicillin Dose
Ask before you take it. The amoxicillin label has no instructions for a double dose, so the right move for your next scheduled dose depends on details a pharmacist or Poison Control can check quickly:
- Which strength you took, and how many tablets.
- When you took each one. Two at once is a different situation than two doses a few hours apart.
- Your schedule. The amoxicillin label says it may be taken every 8 hours or every 12 hours, depending on the strength prescribed.
- Kidney problems, a penicillin allergy history, or other medications you take.
Poison Control points people who took too much amoxicillin to 1-800-222-1222 or its webPOISONCONTROL online tool. Do not try to "cancel out" the mistake by skipping doses on your own.
Took a dose a few hours early instead? See taking antibiotics earlier than scheduled. Missed one? See what to do after a missed dose of amoxicillin.
Is a Double Dose of Augmentin (Amoxicillin-Clavulanate) Different?
Augmentin is amoxicillin combined with clavulanate. The label explains that clavulanate protects amoxicillin from some of the enzymes bacteria use to break it down. If your bottle says amoxicillin and clavulanate potassium, this section is yours.
The combination can be harder on the stomach, even at normal doses. The FDA label for amoxicillin and clavulanate 875 mg/125 mg tablets lists diarrhea or loose stools in 9% of people in trials, nausea in 3%, and skin rash or hives in 3%. The label also notes that side effects, particularly diarrhea, went up at the higher recommended dose.
A 2015 review of 45 placebo-controlled trials in CMAJ linked diarrhea to amoxicillin only in its amoxicillin-clavulanate form, at about 1 extra case for every 10 people treated. So if your double dose was Augmentin, stomach trouble is the more likely thing to show up.
Two more label details matter here:
- The label says to take it at the start of a meal, to help minimize stomach upset.
- The tablets are not interchangeable by strength. The label states that two 250 mg/125 mg tablets are not substitutable for one 500 mg/125 mg tablet. Each of those tablets carries 125 mg of clavulanate, so two of them doubles the clavulanate. Do not try to piece together a dose from different tablets. If you are not sure which tablet you have, ask your pharmacist.
Symptoms to Watch After Taking Too Much Amoxicillin
Poison Control says that often no treatment is needed for an antibiotic overdose, though stomach upset and diarrhea can happen. This table sorts what you might see by what it may mean.
| What you notice | What it may mean | What to do |
|---|---|---|
| Nausea, stomach upset, loose stools | The expected effect of extra antibiotic | Drink fluids. Call your pharmacist if it is severe or will not settle |
| Watery or bloody diarrhea, even days after the course ends | A gut infection the label warns can follow antibiotic use (C. difficile) | Call your prescriber |
| Hives, swelling of the face or lips, trouble breathing | A possible allergic reaction | Call 911 |
| Blood in your urine or much less urine than usual | Crystals in the urine, which the label says have been reported after amoxicillin overdose | Call Poison Control or get medical care today |
The C. difficile and urine warnings come from the Amoxil label, whose overdose section also says keeping up fluid intake helps lower the risk of crystals in the urine.
The amoxicillin label states that serious allergic reactions require immediate emergency treatment, and Poison Control says milder stomach cases can usually be managed at home with extra fluids.
When Symptoms Are NOT Just the Extra Dose
Not every new symptom comes from the second tablet. Some have other causes.
A rash that shows up while you have mono. The amoxicillin and clavulanate label notes that a high percentage of people with mononucleosis who receive amoxicillin develop a red skin rash. If you were given amoxicillin for a sore throat that turned out to be mono, tell your prescriber about the rash.
An allergy to penicillin-type drugs. Poison Control points out that amoxicillin is chemically similar to penicillin, so people allergic to penicillin may react to amoxicillin too.
The infection itself. A fever, or just feeling worse, can be the illness you are being treated for. If you are not improving, that is a question for your prescriber whether or not you doubled a dose.
Who Should Call Sooner
Some people should not wait to see how the day goes:
- You have kidney disease. Your kidneys clear amoxicillin, and the amoxicillin label says high blood levels "may occur more readily" when kidney function is reduced. It also says people with severely reduced kidney function should not receive the 875 mg tablet at all.
- You took more than one extra dose. NHS inform advises speaking to a pharmacist if you accidentally take more than 1 extra dose of an antibiotic, or if side effects are severe.
- You have reacted to penicillin before. Call about any new symptom.
- It was your child's dose, not yours. Poison Control notes that antibiotics for children are dosed by weight, so the math is different. See what to do if you gave your child a double dose of amoxicillin.
Why Double Doses Happen on Twice or Three Times a Day Antibiotics
A short antibiotic course is a new routine you never get the chance to learn. In a small 2021 Swiss study of 68 people on short antibiotic courses, doses were taken on schedule 90.9% of the time on twice-a-day antibiotics and 81.8% on three-times-a-day ones. The authors did not treat that gap as a real difference. Still, a mistimed dose can leave someone wondering "did I take that?", which is how a second dose happens.
For spacing that is easier to follow, see 3 times a day medication timing, what twice a day means on your label, and the missed antibiotic dose guide.
How Pillo Helps
A double dose like this can start with one question: did I already take it? Pillo's persistent alarm keeps going until you mark the dose as taken, so the answer is in your dose history instead of your memory. When you open the app an hour later, you can see the 2 PM dose is already checked off.
For a family, Dependents Management lets one person track a child's or parent's antibiotic course in their own app, with its own schedule. That helps when two courses are running in the same house.
The same mistake lands differently with other drugs, as with taking two blood pressure pills by accident.
Frequently Asked Questions
What happens if I accidentally take a double dose of amoxicillin?
For most adults, an extra dose is unlikely to cause serious harm. Poison Control says antibiotic overdose can cause nausea, vomiting, and diarrhea. Do not take more, and call your pharmacist or Poison Control at 1-800-222-1222 about your next dose.
I took 2 amoxicillin 875 mg at the same time. What should I do?
Do not take another dose until you have talked to a pharmacist or Poison Control. Two 875 mg tablets add up to 1,750 mg. The American Heart Association lists a single 2 g amoxicillin dose before certain dental procedures. That shows doctors use doses in this range on purpose, but it is not a safe limit for you, and your kidney function still matters.
Can you double up on amoxicillin the first day?
No, not on your own. The amoxicillin label says it may be taken every 8 hours or every 12 hours, depending on the strength prescribed, and gives no instruction to double the first dose. Only change a dose if your prescriber tells you to.
Can you overdose on amoxicillin?
Yes, but serious problems are uncommon. Poison Control reports that US poison centers logged over 25,000 antibiotic exposures in 2023 and 1 death. The Amoxil label says crystals in the urine, sometimes leading to kidney failure, have been reported after amoxicillin overdose. Blood in your urine or much less urine than usual needs medical care the same day.
Is taking 2 amoxicillin doses close together worse than taking them hours apart?
NHS inform says there is an increased risk of side effects if you take 2 doses closer together than recommended. Tell the pharmacist exactly when you took each dose, because that changes their advice about your next one.
Is a double dose of Augmentin more likely to cause diarrhea?
It is more likely to upset your stomach than plain amoxicillin. A 2015 review in CMAJ linked diarrhea only to the amoxicillin-clavulanate form. The amoxicillin and clavulanate label lists diarrhea or loose stools in 9% of people at normal doses and notes diarrhea increased at higher recommended doses. Watery or bloody diarrhea is a reason to call your prescriber.
What if my child took a double dose of amoxicillin?
Poison Control notes that antibiotics for children are dosed by weight, so the numbers in this article do not apply. Call Poison Control at 1-800-222-1222, and read what to do after giving a child a double dose of amoxicillin.
Sources
- FDA DailyMed: Amoxil (amoxicillin) tablets prescribing information
- FDA DailyMed: Amoxicillin capsules prescribing information
- FDA DailyMed: Amoxicillin and clavulanate potassium tablets prescribing information
- American Heart Association: Prevention of Viridans Group Streptococcal Infective Endocarditis (Circulation, 2021)
- Gillies et al., Common harms from amoxicillin: a systematic review and meta-analysis (CMAJ, 2015)
- Haag et al., Assessing Medication Adherence Barriers to Short-Term Oral Antibiotic Treatment in Primary Care (IJERPH, 2021)
- Poison Control: Amoxicillin precautions and side effects
- Poison Control: Antibiotics, overdose vs. misuse
- NHS inform: Antibiotics
