Cephalexin (Keflex) – Side Effects You Should Know
By Erica Wilson, Feb-22-2026
Dr. Arjun Srivastav Medical Reviewer (Pharm D)Cephalexin an antibiotic is for use in only bacterial infection cases. However, speaking of the medicine, it has different uses from skin infections, UTIs, respiratory issues and so on.
About the drug type, it is a from the group of cephalosporin group of drugs. When working, this medicine hampers the production of the bacterial cell wall. It damages the cell wall because of which the bacteria eventually die.
Common Uses
One of its common brand names Keflex has uses like:
Skin Infections
- Cellulitis
- Pyoderma
- Abscesses
UTIs:
Infections affecting your bladder, vagina, or kidney.
Respiratory Infections:
- Pneumonia
- Tonsillitis
- Strep throat
Other uses
- Ear infections (otitis media
- bone infections
- dental infections
Mild Side Effects Of Cephalexin
Many people can have mild issues like:
Gastric Issues:
- Diarrhea
- Nausea
- Vomiting
- Heartburn
- Indigestion
- Little stomach pain
Neurological Problems:
- Getting frequent headaches from issues
- Feeling dizzy because
- Feel very tired or fatigued.
Problems Around The Vagina Or Penis:
- Itching
- Irritation
- Yeast infection around
- Vaginal discharge
Aches:
- Joint pains
- Muscle swelling
- Muscle stiffness
How To Manage These Mild Issues Of Using Cephalexin?
➦ Take With Food:
Have some light nutrient meal before taking your dose of Cephalexin 500 mg.
➦ Hydration:
Getting a load of water at this time is highly needed to get rid of issues like tiredness and fatigue out of your body.
➦ Adjusting Your Diet:
The BRAT diet is a choice. Avoid foods that are rich or spicy or fried because these foods can be bad for your stomach. Well, a simple idea is to take any kind of food item that has only a good amount of vitamins and minerals that help boost immunity.
➦ Enough Rest
Of course, one of the simple steps is to take enough rest to feel well again.
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Should You Go To A Doctor With The Mild Side Effects Of Cephalexin?
Most of the times mild issues with Cephadex 500 can be taken care of at home. However, if these mild issues are bothering you a lot it is an idea to see a doctor. If the things that are happening to you are not that bad you should still get in touch with your healthcare provider if you experience things.
Go To The Doctors For
- Severe diarrhea, which is not recovering even after a few days or weeks.
- A skin rash or skin allergy with no signs of cure.
Severe Side Effects – Cephalexin
You should get in touch with your healthcare provider immediately if you notice:
1. Bad Stomach Issues:
- Severe diarrhea
- Stool with blood presence in it.
- Critical stomach cramps
2. Liver Problems:
- Skin turning yellow.
- Dark urine
- Pale, clay-colored stools.
3. Kidney Issues:
- Changes in the amount or frequency of urination
- Blood in the urine,
- Sudden weight gain from fluid buildup
4. Blood Disorders:
- Bruises on skin
- Nosebleeds
- Bleeding from the gums.
- Low blood cell count
5. Neurological Changes:
- Rare reports of seizures
- Confusion
- Hallucinations
How To Manage The Severe Side Effects Of Cephalexin?
➤ In Case Of Severe Diarrhea
If you have bad diarrhea with watery or bloody stools and a fever, you should not take medicines like Imodium that you can buy at the store. These medicines can keep things inside your body and cause infections to grow. You need to call your doctor away so they can do some tests and give you special antibiotics.
➤ Liver or Kidney Damage:
When these things happen, you need to go see a doctor. They may prescribe you to some medicines or suitable remedies along with the medicine.
➤ For Skin Rashes, Blisters
If you have a rash that hurts a lot, if it is blistering, or if it is on your mouth or eyes you should go to the emergency department immediately.
You should not wait to get help if your rash is severe, especially if it is, on your mouth or eyes because these conditions can be very dangerous.
Severe Emergency Allergic Issues With Cephalexin
1. Anaphylaxis
This is an allergic reaction usually happens within a few minutes to a few hours of taking the drug. You might have trouble breathing. Your face tongue or throat might swell up. Anaphylaxis can also cause your heart to beat fast, or you might even faint. Anaphylaxis is a scary thing, and it can happen when you take the drug.
2. Severe Skin Reactions
Look out for symptoms that feel like the flu. In addition, you may have a fever and body aches when body temperature rises. After that, you might get a red or purple rash.
Sometimes the rash can even affect the mouth, eyes, or private parts, like the genitals. Severe Skin Reactions are a deal, and you need to watch out for them.
Managing The Emergency Allergic Side Effects Of Keflex
If you are taking, cephalexin and you have a reaction you need to get help right away from a doctor or a hospital. Here is what you should do.
1. Call Emergency Services
Well, get in touch with an emergency doctor or rush to a hospital if things go out of control.
2. Use Epinephrine:
If you have an Epinephrine auto injector, like an EpiPen that the doctor gave you should use it away. You need to put it in the part of your thigh. Remember to use the Epinephrine auto injector like the EpiPen soon as you can.
3. Positioning:
- When you are in this situation, you should lie flat on your back. It is an idea to elevate your legs to help your blood flow.
- However, if you are having trouble breathing then it is better to sit up.
- If you start vomiting, you need to turn onto your side so that you do not choke on the vomit.
- If you have taken much cephalexin, stop taking the medicine right away and do not take another dose of cephalexin.
Long-Term Side Effect Management With Cephalexin Or Keflex
Medical Alert:
Stay on alert; well, we suggest that you be highly cautious of using your dose to the exact amount that the doctors have told you to. Take their help for any case or when you have any confusion.
Update Records:
Get to the doctors as you start using the medicine for a few weeks to know if you need any changes in your dose.
Years of Experience: 10+ years Education: B.Sc. in Biomedical Science (Monash University, Melbourne, Australia) PG Diploma in Health & Medical Communication (University of Sydney, Australia) Experience: Erica Wilson is an…
