Antibiotics and Period: the Effect of Antibiotics on Your Period


Antibiotics get a bum rap, but the truth is that without them, many of us wouldn’t be here. It’s true that the advent of antibiotics was a game-changer for the medical industry, but overuse has led to negative consequences. In fact, antibiotic use can affect nearly every part of your body from your gut to your reproductive system.

Make it short – can antibiotics affect your period? Absolutely.

Antibiotics and Period: A Love-Hate Relationship

Antibiotics medicine isolate on white.Antibiotics and your period have a love-hate relationship. Although they get rid of the bad (and good) bacteria in the body, they also make estrogen less available. Without enough estrogen, proper menstrual cycle function is impossible.

When you take antibiotics, it can affect your menstrual cycle in a few different ways.

First, it affects the speed that estrogen is metabolized. This is because antibiotics are metabolized by the liver, which is the same organ that metabolizes estrogen and progesterone.

When estrogen is metabolized at a slower pace, less of the hormone is available in the bloodstream. Why is this a big deal? Estrogen is required during the follicular phase of the menstrual cycle to stimulate the ovaries and also thicken the uterine wall. Lack of estrogen can cause a delay in ovulation or a woman to skip ovulation altogether.

Second, antibiotics kill off the good bacteria in your gut. To understand how this affects your cycle, you need to understand how estrogen works. Once the liver metabolizes estrogen, it’s moved to the digestive tract and either reabsorbed or excreted. The good bacteria in your gut breaks down the estrogen into active estrogens, which can then be reabsorbed into the bloodstream. If antibiotics are killing the good bacteria in your gut, active estrogens may never make it back into your bloodstream.

On top of all this, many antibiotics cause diarrhea, which consequently causes you to excrete more estrogen.

When estrogen is excreted too quickly, it can cause a dramatic drop in estrogen levels and affect your cycle.

[Read more about Period]

Can Antibiotics Make Your Period Late?

Girl in red shorts holding a white hygienic tampons and pads during menstruation calendar.Can antibiotics delay your period? Yes.

If antibiotics are affecting your estrogen levels, you may not ovulate, or ovulation may occur later than normal. If ovulation is delayed, your period will be delayed, too. Many women who are on a course of heavy antibiotics experience late periods.

That being said, there are also other things that can make your period late that aren’t antibiotics-related. These include:

  • Stress
  • Thyroid disease
  • PCOS
  • Birth control usage
  • A significant change in weight

Whether it’s the antibiotics or one of the culprits listed above, you can find peace of mind in knowing that your cycle should return to normal once the issue is resolved.

Can Antibiotics Affect a Pregnancy Test?

In most cases, antibiotics will not affect a pregnancy test. These tests are designed to detect pregnancy hormones, or hCG, not estrogen.

If you’re taking antibiotics for an illness, it may affect your menstrual cycle. Most women experience no change, but a heavy course of antibiotics can delay your period. It is possible to counteract these changes by taking a good quality probiotic to restore the population of good bacteria in your gut.


  1. After taking two rounds of antibiotics my period ended up being late 20 days and had it for 6 days and now after a month I havent had another period I’m already 5 days late my concern is will my period ever go back to normal??? Or is this normal after so much antibiotics?

  2. I took antibiotics for 6 days during my ovulation days cause of some work I had done on my teeth, now I’m 7 days late for my period. Is it delayed or am I pregnant?

  3. I was on antibiotics Cipro for 21 days the following month I had a normal period but this month I am 11 days late and three negative test. I went to my doctor to get blood work done wont know results until Monday. Is this normal for antibiotics? I have always had a normal cycle and on time.

  4. I took metronidazole 500/mg for 7 days. I finished the antibiotics 5 days before my period was supposed to happen. I had unprotected sex 5 days after my last period. I am late 2days now . I am having symptoms of PMS or pregnancy but I took 2tests the day before my period was supposed to come. Both negative. Am I late because of the antibiotics or something else?

  5. I took Doxycycline Antibiotics For the past 3day now but Am still taking it. I was supposed to see my period yesterday but am having sysptom’s of PMS since last week, but it as stopped dis morning OR Am Pregnant… I mine late because am using Antibiotics Or what?

  6. i used Doxycycline Antibiotics for nearly 6 months now for my acne and this the worst my period has gotten. its nealy 20 days late and last month it was 14 days late. im so worried. someone tell me is this normal.

  7. I took antibiotics for 7 days and I finished them 13 days ago. My cycle was supposed to start about 2 days ago. It’s crazy because I am having the symptoms of PMS even slight cramping but no cycle.

  8. about 15 days before I was admit in hospital suffering from typhoid and now my periods are late by 7 days and still its not yet came so what’s the reason

  9. hi, i was taking antibiotics last week for about 6 days,i was never late in my mentrual cycle of 30 days,but now im 3 days delay and i had done 3 pregnancy tests with urine samples negative and my beta hcg level in bloood is o.1 within normal range,was it because of antibiotics also?

  10. I took Augmentin 500mg same day my period was suppose to start and after 6 days i have not had it yet. Could the delay be the antibiotics? Have not had a pregnancy test yet. Has anyone had the same problem?

    • Yes…mine is fresh …am 2days later ….i took antibiotics injection for 4days…having cramps like PMS…but no period showing. Can’t say pregnant because my husband don’t stay in the country with me…it is delay of the antibiotics as i read earlier on internet. Sorry

  11. I took antibiotics mid cycle and now I’m 42 days late… took a pregnancy test yesterday, all my tests are Neg. when do I get my period again? I miss it….

  12. I took bitcham ampiclus during my ovulation. Now am 3days late for my menstrual cycle, is it as a cause of the antibiotic?

  13. I took triple therapy: clarithamycin, amoxicillin and metronidazole for H pylori for 14 days and now my period is going on seven days late. Ovulation was two days before I was supposed to get my usual 35 day cycle. Before I found out I had h pylori my cycles were getting later and later each month, and my periods were shorter and shorter 5 days down to only two days. Then I had started on the triple therapy. Took a pregnancy test and it was negative.

  14. I am taking some set of supplements(Propolis, aloe vera plus capsule and Royal jelly), my menses came later than normal( less three days). Can this affect my chances of getting pregnant even after quitting supplements seven days after menses?

  15. I am taking bactrim 2x/day for 7 days for a critical high UTI. Am NEVER late but now I am….havent taken a pregnancy test yet…At 41, am afraid to. LOL…
    Does bactrim cause late menustratiin?

    • I was late too taking this. I finally started after 5 days late . Now, I normally only have a period for at least 7 days. I stopped for a day and now spotting again. I’ve been done with my meds for about 3 days now. I’m just scared something is wrong. I was taking the meds for 10 days!

  16. I stopped taking antibiotics and now my period has been delayed 4 days. Pregnancy tests are negative, but my periods are usually regular. I am concerned.

  17. I have been on antibiotics for 8 days my period came on on the 6 th and it’s been on for 10 days I was wondering if the antibiotic has something to do with it not going off

    • I experienced the same thing I took an antibiotic drugs and my period became heavier than normal and it came out for 7 days before it stops thou I had unprotected sex before my period came pls what could be the reason of the heavy period?

  18. Yes! LADIES it is normal and common. I see a million questions and no answers. No matter the type, name, brand, or strength of antibiotic(s) your on it can and will effect your period. Take a PROBIOTIC to bring your good bacteria back up due to the antibiotics destroying them. This will help your hormone ESTROGEN to be absorbed back into your BLOODSTREAM?

  19. Mine is the opposite, I just finished treating a long pneumonia with ceftriaxone injection and azithromax tab, to my utmost surprise my period came 9days early. Pls any need to worry?

  20. Hi I am currently using amoxicillin to treat tooth ache and I have just finished my menses 2 days before I started using d drug. What i noticed in my body is pain and bloating in my pelvis. Could it be d work of d antibiotic I am using?

  21. I had severe infection doctor recommended me augmentin 625mg three times a day for 6 days i completed my therapy 5 days ago the period date..
    i got my periods on time with minute bleeding even very next month again i got my period exact on date with very minute bleeding whats wrong plz guide

  22. I finished a 7 day round of Bactrim for a UTI on 3/5/18. My cycles range from 25-28 days but I average 26 days (very regular). I’m on day 28 today and no period yet! I’ve had the usual signs like aching and stuff but I’m concerned the meds have caused a change in my cycle. I plan to take a pregnancy test if I don’t start by day 30 but I am STRESSING OUT :/

    I will update once I find out what the deal is

  23. UPDATE: Took a pregnancy test on 3/17 and it came back negative. I woke up this morning, 3/18, to bleeding and clots. According to my cycle tracking app my ovulation must have been delayed by nearly a week! This makes sense because I started antibiotics 4 days before my ovulation day.

    Glad my period finally showed! Good luck to all the worried or confused ladies out there. I’m now convinced that meds can alter your cycle, despite what doctors may tell you

  24. I was in the hospital last week, 3 days before my period was supposed to show. It was found I had a kidney infection so they gave me IV antibiotics AND Macrobid antibiotics by mouth that I took for 5 days. Now my period is 5 days late. I have no clue what’s going on. I’ve been taking a gummy probiotic since the day I started antibiotics. Took 3 preg tests, all negative.

  25. I gave birth on 2014 then took patogen till this year for prevention, no period occur during all this years and now I want to clear my womb was suppose to go back into my injection two months ago BT I didn’t and still not experiencing mentruation,today I used flagyl,will it gain my period back or I will experience discharge first in fact I want a baby again must I wait for period or it will happens anytime soon?

  26. Hi. I just finished my medications of pneumonia last 26th of March. I took 1gm of Amoclav. Period should be on the last week and took pregnancy test because of late menstruation. I am delay now for almost 2 weeks. Is this really normal? Never encountered late menstruation before.

  27. Hi. I took 3 antibiotics a day for 10 days, while I was ovulating, I’m now 8 days late, and I’m getting very anxious. Me and my so had sex the day after my period ended, but yesterday I spotted a bit. Any ideas?

  28. Hi,
    I always had a regural cycle of 28days so when I took for 7 days amoxillin for an ear infection my period got delay. 4days after I finished my course my period came. So do not worry your period will come eventually. Try drinking a lot of water to flush out from your body the antibiotics.

  29. I had unprotected sex on Apr 16-17. My period came right on time the following month (May 9-13 to be exact). It was accompanied by a cough that leads up to this day. I had to take Augmentin for 10 days. My period hasn’t shown yet this month. I was due on June 6. Should I be worried?

  30. Hi good morning
    i took two 500mg of amoxillin when treating for typhoid and now the month is almost ending i haven’t seen my menstruation, i did a pregnancy test on 27/10/2018 and its was negative.
    please advice me what i should do or take….


  31. I took antibiotics for UTI and pobiotics. My period came as expected but it came out as more of little little clot and flows more when I urinate. Please do you have any idea h


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