What Is the Difference between Doxycycline and Amoxicillin?

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  • Written By: B. Chisholm
  • Edited By: O. Wallace
  • Last Modified Date: 31 July 2019
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Both doxycycline and amoxicillin are antibiotics. They belong to different classes and have different mechanisms of action. While they both have broad spectrum activity against various gram-positive and gram-negative bacteria, some resistance has developed to both drugs. The choice of which antibiotic to use will be made by the treating doctor according to the illness, organism causing it, and susceptibility of the organism.

While both antibiotics fight bacterial infections, the way in which they do that differs. Doxycycline belongs to the class of drugs called tetracyclines, which work by interfering with protein synthesis of the bacteria, thus not allowing the organism to replicate. It is referred to as a bacteriostatic agent, which means that it stops the bacteria from multiplying. The body's immune system kills off the bacteria already there.

Doxycycline is used to treat a range of susceptible conditions including genital infections, lung infections and ricketsial diseases. Due to the development of bacterial resistance its role in bacterial infections has decreased slightly. It may also be used longer term, to treat severe acne. Doxycycline is also used for malaria prophylaxis and, in combination with other drugs, malaria treatment.


Amoxicillin is a beta-lactamase sensitive penicillin with extended spectrum. It works by interfering with bacterial cell walls. Again, resistance has developed in some organisms, so it is often combined with another drug, clavulanic acid, which has restored its effectiveness. Amoxicillin is generally used to treat infections such as otitis media, sinusitis and lower respiratory tract infections.

As with any medication, both doxycycline and amoxicillin may interact with other medications, the oral contraceptive pill being one of them. All drugs, including over-the-counter, homeopathic and complementary medications should be discussed with the doctor. Pregnancy, desired pregnancy and lactation should also be discussed. Pregnant women should not take doxycycline, though amoxicillin is considered relatively safe during pregnancy.

Completing the course of an antibiotic is essential and this applies to both doxycycline and amoxicillin. Stopping a course before completion increases the risk of developing resistance, making treatment of future infections far more difficult. The prescribed dose and duration should be followed exactly.

Both drugs may cause adverse effects, some gastrointestinal, such as nausea, vomiting and diarrhea. Should these be severe, the doctor should be consulted. Taking doxycycline and amoxicillin with food may help to reduce the gastrointestinal side effects. Doxycycline may cause irritation of the esophagus, or throat, so it is recommended that it is taken with a large glass of water, while in an upright position, and to avoid lying down for some time after.


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Post 6

I was prescribed doxycycline for two years after IV antibiotics. I do feel like it's has affected me in a bad way -- my teeth and whole body.

Post 5

Tell me the best medication for lyme disease.

Post 4

I don't feel any different when I take doxycycline, but I feel terrible while taking amoxicillin. Doxycycline just seems so much gentler on my stomach.

Amoxicillin makes everything taste bad. Not long after taking my first dose, everything that I put in my mouth seems bitter. Even water tastes horrible, and it doesn't even have a flavor!

I do tend to get nauseated while on amoxicillin, as well. It's too bad that doxycyline can't be used to treat everything that amoxicillin can. I always dread the next two weeks when I find out that I have to start taking amoxicillin!

Post 3

@Oceana – Degree of sun sensitivity is a major difference between doxycycline and amoxicillin. Doxycycline can cause you to get sunburned badly in half an hour, but amoxicillin seems to have no effect on how quickly you burn.

I have taken amoxicillin for sinus infections, and I had no problems with burning, even though I stayed in the pool for hours while on the antibiotic. Of course, I wore sunscreen, but with doxycycline, even that doesn't seem to help much.

I went to the beach while on doxycycline. I wore a 30 SPF sunscreen, which I reapplied every two hours, yet I still got the worst sunburn of my life. One spot on my arm burned so badly that it developed black scabs a week later!

Post 2

@JackWhack – My dermatologist kept me on doxycycline for six months, but I have heard of other people being on it for a year or more. I suppose it just depends on how severe your case is and how well you respond to it.

My acne was really concentrated along my jawline. I had swollen red clusters of bumps here and on my chin, and they were hard to cover even with makeup.

After several chemical peels and a couple of months on doxycycline, my acne problem was drastically reduced. The only side effect was sun sensitivity, but since I took it during the fall and winter, this didn't really matter to me.

Post 1

I have taken amoxicillin several times before for respiratory tract infections, but I have never had any experience with doxycycline. I find it interesting that an antibiotic can be used to treat acne, though.

How long can a person take doxycycline for acne? I know the article says it can be used long term, but are we talking weeks, months, or years?

I am interested because I suffer from adult acne, and I know that it is a tough kind to treat. Topical creams have not worked, but perhaps an antibiotic would be effective.

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