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Rx capsule vs. tablet:
Drug vs. Drug

Doxycycline vs. amoxicillin: Uses, side effects, and cost comparison

The effectiveness of doxycycline or amoxicillin depends on the type of infection being treated
Gerardo Sison medical writer headshot
By | Jul. 1, 2024

Key takeaways

  • Doxycycline and amoxicillin are both broad-spectrum antibiotics but work differently.

  • Both antibiotics can cause gastrointestinal side effects like nausea and diarrhea.

  • Doxycycline is more likely to interact with antacids and dairy products, while amoxicillin interacts with blood thinners.

  • Pregnant women should avoid doxycycline but can usually take amoxicillin under medical guidance.

In this article:

Bacterial infections are common, with mild to serious and even life-threatening symptoms. However, they are entirely curable with the right antibiotics. If you experience a bacterial respiratory or urinary tract infection, among other infections, you may be prescribed an antibiotic, such as doxycycline or amoxicillin. 

Doxycycline and amoxicillin are generic antibiotics commonly prescribed for various bacterial infections. As generic options, they are accessible and typically covered by insurance and Medicare. However, they should only be used with the guidance of a healthcare provider or doctor. These antibiotics may differ in how they work and what they’re used for.

What are the main differences between doxycycline and amoxicillin?

Doxycycline and amoxicillin are both broad-spectrum antibiotics, meaning they can target a wide range of bacteria. However, they belong to different classes and have distinct properties.

Mechanism of action

Doxycycline belongs to the tetracycline class of antibiotics. It works by blocking protein synthesis in bacteria, effectively stopping their growth. Amoxicillin, on the other hand, is a penicillin-type antibiotic. It works by disrupting the formation of bacterial cell walls, leading to the death of bacteria.

There are two main forms of doxycycline: doxycycline monohydrate and doxycycline hyclate. Doxycycline monohydrate tends to be less irritating to the gastrointestinal tract compared to doxycycline hyclate, which can cause more stomach upset in some individuals. However, both forms are equally effective in treating bacterial infections.

Dosage and dosage forms

Doxycycline is commonly available in several forms, such as capsules, oral suspensions, and delayed-release tablets. Depending on the infection, it is typically taken as a 100 mg tablet twice daily for seven to ten days or longer.

Amoxicillin is also available in various forms, including capsules, oral suspensions, and chewable tablets. It is generally prescribed in dosages that depend on the type and severity of the infection. For adults, a common amoxicillin dosage is 500 mg every eight hours or 875 mg every 12 hours for seven to 14 days.

A healthcare provider will determine the exact duration and dosage of these antibiotics based on the infection and the individual’s medical history.

Doxycycline vs. amoxicillin
Doxycycline Amoxicillin
Drug class Tetracycline antibiotic Penicillin antibiotic
Brand/generic status Brand and generic versions available Brand and generic versions available
What is the brand name? Vibramycin

Doryx

Adoxa

Monodox

Oracea

 Amoxil

Moxatag

Trimox

Dispermox
What form(s) does the drug come in? Oral tablet

Oral delayed-release tablet

Oral capsule

Oral suspension

 Oral tablet

Oral tablet, chewable

Oral capsule

Oral suspension
What is the standard dosage? Dosage depends on the infection being treated  Dosage depends on the infection being treated 
How long is the typical treatment? Duration depends on the infection being treated Duration depends on the infection being treated
Who typically uses the medication? Adults and children  Adults and children 

Conditions treated by doxycycline and amoxicillin 

Doxycycline and amoxicillin both treat bacterial infections. They are ineffective against viral, parasitic, or fungal infections and should only be used with guidance from a healthcare provider. 

Doxycycline

Doxycycline is used to treat various infections, including:

  • Tick-borne illnesses, such as Rocky Mountain spotted fever, typhus fever, Q fever, and other tick-related fevers
  • Respiratory infections caused by Mycoplasma pneumoniae
  • Sexually transmitted infections, such as Lymphogranuloma venereum, psittacosis, and uncomplicated urethral, endocervical, or rectal infections caused by Chlamydia
  • Eye infections, such as inclusion conjunctivitis
  • Urinary infections, such as nongonococcal urethritis
  • Other infections, such as relapsing fever, chancroid, plague, tularemia, cholera, brucellosis, bartonellosis, and granuloma inguinale

Doxycycline also treats infections caused by certain bacteria, like:

  • Gram-negative bacteria: E. coli, Enterobacter, Shigella, Acinetobacter, and Haemophilus influenzae
  • Gram-positive bacteria: Streptococcus pneumoniae and Bacillus anthracis (anthrax)

Doxycycline can also help treat severe acne and prevent malaria in travelers.

Amoxicillin

Amoxicillin treats various bacterial infections, including:

  • Ear, nose, and throat infections caused by Streptococcus, Streptococcus pneumoniae, Staphylococcus, or Haemophilus influenzae
  • Urinary tract infections caused by E. coli, Proteus mirabilis, or Enterococcus faecalis
  • Skin infections caused by Streptococcus, Staphylococcus, or E. coli
  • Respiratory infections caused by Streptococcus, S. pneumoniae, Staphylococcus, or Haemophilus influenzae

For adults, amoxicillin also treats H. pylori infections and duodenal ulcers when combined with other drugs like clarithromycin and lansoprazole.

Doxycycline and amoxicillin should only be used to treat infections caused by bacteria to prevent drug-resistant bacteria and ensure antibiotics remain effective. Healthcare providers may use culture and susceptibility information to choose the right antibiotic. 

Is doxycycline or amoxicillin more effective?

Doxycycline and amoxicillin are both effective antibiotics. The most effective antibiotic will depend on the specific bacteria causing the infection. For example, amoxicillin may be an effective antibiotic for bacterial infections that are not resistant to penicillin. In some cases, doxycycline may be an appropriate option for some penicillin-resistant infections. 

One study involving 267 patients found that both doxycycline and amoxicillin were generally effective in treating respiratory infections, with only 7 out of 134 patients on doxycycline and 13 out of 133 patients on amoxicillin not improving. 

Another study examined the effectiveness of two different antibiotic treatments for people with H. pylori-related stomach ulcers. It found that using doxycycline or amoxicillin, along with other medications, led to high success rates in getting rid of the bacteria, with around 85% success in both treatment groups. Both treatments were also safe, with only 9 out of 184 participants experiencing mild side effects.

A healthcare provider should determine the most effective medication for a patient, given the patient’s medical condition, history, and current medications.

Coverage and cost comparison of doxycycline vs. amoxicillin 

Doxycycline and amoxicillin are generic medications typically covered by most commercial insurance and Medicare plans. As generic drugs, they may be more accessible than similar brand-name drugs.

Without insurance coverage, the cash price of these antibiotics can vary. Different factors, such as pharmacy location and the quantity prescribed, can affect the overall price. SingleCare coupons may help reduce out-of-pocket costs. SingleCare’s coupon pages for doxycycline and amoxicillin offer discounts that may be used at participating pharmacies. 

Doxycycline Amoxicillin
Typically covered by insurance? Example: Yes Yes
Typically covered by Medicare Part D? Example: No Yes
Quantity Example: 30, 15 mg tablets 21, 500 mg capsules
Typical Medicare copay Example: $10 $0-$10
SingleCare cost Example: $10 $0.60

Common side effects of doxycycline and amoxicillin 

Like other antibiotics, doxycycline and amoxicillin may commonly cause gastrointestinal side effects, such as nausea, vomiting, and diarrhea. In addition, both antibiotics may cause similar side effects, such as rash, tooth discoloration, and dizziness. 

Unlike amoxicillin, doxycycline is more likely to cause photosensitivity. This means that individuals taking doxycycline should be cautious about sun exposure, as it can increase the risk of sunburn. 

Although rare, doxycycline may also cause ulcers in the esophagus and decreased appetite. On the other hand, amoxicillin may be more likely to cause headaches than doxycycline.

Both antibiotics may risk severe side effects, including allergic and skin reactions. Seek medical attention if you experience a severe rash, difficulty breathing, or swelling of the face or throat. 

Doxycycline Amoxicillin
Side Effect Applicable? Applicable?
Diarrhea Yes Yes
Nausea Yes Yes
Rash Yes Yes
Vomiting Yes Yes
Photosensitivity Yes No
Headache No Yes
Tooth discoloration Yes Yes
Dizziness Yes Yes
Esophageal ulcers Yes No
Decreased appetite Yes No

Frequency is not based on data from a head-to-head trial. This may not be a complete list of adverse effects that can occur. Please refer to your doctor or healthcare provider to learn more.

Source: DailyMed (Doxycycline), DailyMed (Amoxicillin)

Drug interactions of doxycycline vs. amoxicillin 

Doxycycline and amoxicillin may interact with different drugs in the body. Dairy products, antacids, and supplements that contain calcium, iron, magnesium, or sodium bicarbonate can reduce the drug’s effectiveness by binding to it in the gastrointestinal tract. Doxycycline should be taken at least two hours apart from these substances.

Barbiturates and certain anticonvulsants may decrease the half-life of doxycycline. In other words, doxycycline may be eliminated from their body more quickly. As a result, the effectiveness of doxycycline could be reduced because it won’t stay in the body as long as expected.

Amoxicillin may have fewer drug interactions than doxycycline. Taking amoxicillin with probenecid may lead to increased blood levels of amoxicillin. Combining amoxicillin with allopurinol may lead to an increased risk of rashes. In addition, amoxicillin may interact with blood thinners like warfarin, increasing the risk of bleeding.

According to their drug labels, doxycycline and amoxicillin may decrease the absorption of birth control pills, decreasing their efficacy. Therefore, it may be recommended to use an additional form of contraception while taking these antibiotics. However, the data is lacking. 

Drug Drug Class Doxycycline Amoxicillin
Maalox (aluminum hydroxide/magnesium hydroxide)

Tums (calcium carbonate)

Milk of Magnesia (magnesium hydroxide)

 Antacids containing aluminum, calcium, or magnesium Yes No
Ferro-Sequels (ferrous fumarate)

Feosol (ferrous sulfate)

Fer-In-Sol (ferrous gluconate)

Pepto-Bismol (bismuth subsalicylate)

 Iron-containing preparations Yes No
Luminal (phenobarbital)

Nembutal (pentobarbital)

 Barbiturates Yes No
Tegretol (carbamazepine)

Dilantin (phenytoin)

 Anticonvulsant Yes No
Benemid (probenecid) Uricosuric No Yes
Zyloprim (allopurinol) Xanthine oxidase inhibitor No Yes
Coumadin (warfarin) Anticoagulant No Yes
Estinyl (ethinyl estradiol)

Plan B (levonorgestrel)

Ortho-Novum (norethindrone)

 Oral contraceptive Yes Yes

This may not be a complete list of all possible drug interactions. Consult a doctor about all medications you may be taking.

Warnings of doxycycline and amoxicillin 

Patients with a medical history of allergies should be cautious with both antibiotics. Doxycycline and amoxicillin can cause severe allergic reactions like rash, itching, and anaphylaxis.

Severe skin reactions such as Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) can occur with both doxycycline and amoxicillin, though they are rare. Symptoms include blistering, peeling skin, and sores on mucous membranes. If you notice unusual skin changes or rashes, stop taking the medication and seek emergency care.

Both doxycycline and amoxicillin can cause Clostridioides difficile-associated diarrhea (CDAD), which is a potentially severe condition. Symptoms include severe diarrhea, abdominal pain, and fever. If you experience these symptoms while taking either antibiotic, contact your healthcare provider immediately.

Consult a healthcare provider for other warnings and precautions before using an antibiotic. 

Frequently asked questions about doxycycline and. amoxicillin 

What is doxycycline?

Doxycycline belongs to a broad-spectrum class of antibiotics called tetracyclines. Tetracyclines work by blocking protein synthesis in bacteria, stopping their growth. This makes doxycycline effective against various bacterial infections, including those affecting the skin, respiratory system, and urinary tract.

What is amoxicillin?

Amoxicillin is a penicillin-based antibiotic used to treat various bacterial infections, such as pneumonia, bronchitis, and ear, nose, throat, skin, and urinary tract infections. It works by disrupting the bacterial cell wall and directly killing the bacteria.

Are doxycycline and amoxicillin the same?

No, doxycycline and amoxicillin are not the same. Doxycycline is a tetracycline antibiotic, while amoxicillin is a penicillin antibiotic. Due to their differences, they are used to treat various types of infections and have different guidelines on interactions and side effects. For example, doxycycline should not be taken with antacids containing aluminum, magnesium, or calcium.

Is doxycycline or amoxicillin better?

The effectiveness of doxycycline or amoxicillin depends on the type of infection being treated. A healthcare provider should choose between them based on the type of infection and patient factors, such as allergies to antibiotics and age.

Can I use doxycycline or amoxicillin while pregnant?

Doxycycline is generally not recommended during pregnancy because it could affect the developing baby’s teeth and bones. On the other hand, amoxicillin is considered safer for use during pregnancy. It’s important to consult a healthcare provider to discuss the risks and benefits before taking any medication while pregnant.

Can I use doxycycline or amoxicillin with alcohol?

Alcohol is not known to interact with doxycycline or amoxicillin, but it’s best to avoid heavy drinking. Alcohol doesn’t reduce the effectiveness of these antibiotics, but it can increase the risk of side effects and make it harder for your body to fight the infection. Moderation is key; consulting your healthcare provider for personalized advice is always a good idea.