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Keflex and Headaches: What Users Say

Headaches: mentioned by 8 users (8.8%)

Based on user experiences from 91 Keflex reviews, the following table shows the most commonly mentioned side effects.

All user comments are moderated by Drugs.com. Each review is verified for relevance and screened for inappropriate content. Side effects are user-reported and not clinically verified.

nausea 14.3%
diarrhea 9.9%
headaches 8.8%
upset stomach 7.7%
dizziness 6.6%
tiredness 5.5%
fatigue 4.4%
gas 4.4%
rash 4.4%
depression 3.3%

Reviews for Keflex

Commonly mentioned side effects
  • Fat...
  • Taken for less than 1 month
  • June 6, 2020

For Bladder Infection "So I ended a Saturday at the ER. I ended up having a urinary infection, a severe one. The PA prescribed Keflex 500 mg for 7 days - it really helped after 2 days, but I noticed that it does bring out side effects on myself. I feel nauseous, tired, agitated, eyes feel hot, headaches. Even though I took 2 Advil, it was still there. I also feel super anxious, I've been having mood swings, I feel more sad, and somehow more depressed than I have been in the past. And I still have one more day to go."

8 / 10
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86 Report
  • Jea...
  • Taken for less than 1 month
  • May 28, 2019

For Bladder Infection "Took a 500 mg dose of Keflex twice a day for one week - I had a UTI. Side effects were diarrhea, headaches, felt depressed, upset stomach, and nausea. Now I’m having stomach cramping. Just hope the urinary tract infection I had is gone after taking this strong antibiotic."

10 / 10
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52 Report
  • cur...
  • Taken for 5 to 10 years
  • March 2, 2022

For Bladder Infection "I have been prescribed Keflex since they stopped using Cipro for that a few years ago. Works great every time and works within hours. Makes me a little tired and I have a bit of a headache, but I think that might have to do with my body trying to heal itself. I always ask for it if it will treat the bacteria that caused my UTI. They won't prescribe this for some bacteria... FYI. I like that this drug has been around for years and years. Makes me feel safer about taking it."

10 / 10
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15 Report

Frequently asked questions

  • Sam...
  • June 23, 2021

For Bladder Infection "I've always taken ciprofloxacin for my chronic bladder infections, but this time around my doctor said he can't give it to me because of a new study that has nothing to do with me. So... I get Keflex. It's extremely slow at getting to the infection. I'm on day three, and I'm just now starting to feel a little better... I think. It also gives me horrific heartburn, headaches, fatigue, and I can't poop."

4 / 10
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17 Report
  • Tes...
  • Taken for less than 1 month
  • July 8, 2019

For Acne "I started taking this medication initially for an infection from a bug bite. After three days of being on the medication, I noticed all of my skin is clear and appears to be glowing, and my pores have shrunk so much. I’m in my early 30s and still suffer from acne occasionally, mostly hormonal acne, and this is amazing. I don’t want to get off of it now. I was on doxycycline for months in my early 20s, which also had a similar effect. The only side effects from this medication initially were a headache and diarrhea, but that went away after one day, and I’m staying on probiotics to help regulate."

10 / 10
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22 Report

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  • ArI...
  • May 11, 2011

For Acne "After taking doxycycline for a while, my body became resistant to it, so my dermatologist switched me to Keflex for acne. I think I had at least five bowel movements the first day. Eventually, my digestive system became somewhat regular, but then I started getting headaches on a regular basis. It cleared up my acne somewhat, but it was definitely not worth all the side effects."

2 / 10
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36 Report
  • Not...
  • August 15, 2021

For Bladder Infection "I took Keflex once and was fine, and then my UTI returned a month later. Doctor put me back on it, and I had the worst reaction. Vomiting, joint pain, headaches - it was awful! I won't take it again, I'll stick with Cipro or Bactrim."

2 / 10
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4 Report
  • Anonymous
  • June 6, 2011

For Acne "This was and continues to be the best, long-term option for me. I had very little side effects ... slight headache at first, but it went away after a few days."

10 / 10
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28 Report

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Reviews may be edited to correct grammar/spelling or remove inappropriate content. Reviews appearing to come from parties with a vested interest are not published. This information is not intended to endorse any medication and should not replace the expertise and judgment of healthcare professionals.