Can You Take Bactrim And Amoxicillin Together? (+4 Safety Tips)

There are cases where two antibiotics are required to effectively treat a particular infection. This is mostly beneficial when each antibiotic has coverage for only a limited species of bacteria. Combining the two agents can allow for wider coverage and better treatment outcomes. 

However, before this is done, it must be ascertained that the two antibiotics do not interact with each other. In this article, the pharmacist will let you know if it is safe to take Bactrim and amoxicillin together.

Antibiotics are medications used to treat infections caused only by bacteria. Some of them have a wider coverage (broad spectrum) than others and also work differently to kill or stop the growth of bacteria in the body. Bactrim and Amoxicillin are both Antibiotics.

Can you take bactrim and amoxicillin together?

There is no known interaction between bactrim (trimethoprim/sulfamethoxazole) and amoxicillin. As such, they can be safely used together but only if instructed by your doctor to do so. 

Even though there is no record of a dangerous interaction between bactrim and amoxicillin, using the two together can still put you at risk of experiencing a common side effect called Antibiotic-associated diarrhea (AAD).

Drugs in certain classes of antibiotics are more likely to cause diarrhea than others. Examples of such antibiotic classes are cephalosporin, penicillins, macrolides, fluoroquinolones, etc. Amoxicillin belongs to the penicillin family and is likely to cause diarrhea.

What is Antibiotic-associated diarrhea?

Antibiotic-associated diarrhea (AAD) is when you pass loose, watery stool more than three times in a day, after taking an antibiotic medication. It is a common side effect associated with antibiotic treatment. 

It is estimated that about 5 to 25% of adults undergoing treatment with antibiotics are likely to develop AAD [1]. Antibiotic-associated diarrhea occurs when the balance between good and harmful bacteria present in the gut is disrupted.

When you use antibiotics for treatment, it can kill both the good and the harmful bacteria in your system. The good bacteria help your body digest food properly and also prevent the growth of some harmful bacteria. 

Good bacteria also help to keep some opportunistic bacteria in check. Opportunistic bacteria are bacteria that are not normally harmful but can cause infections when the body’s immune system is low. An example is Clostridium difficile

When the gut balance is disrupted, you end up having more harmful bacteria like clostridium difficile, than good ones. You can develop watery stool. Your risk of developing AAD is higher when you take more than one antibiotic and also for a prolonged period.

About Bactrim

Bactrim is a brand name for a combination drug consisting of Trimethoprim and sulfamethoxazole. It is also commonly referred to as cotrimoxazole. Bactrim works by blocking folate which is necessary for bacteria to produce DNA. Without this, they can’t grow or multiply. Hence their death.

Bacterial Coverage of Bactrim and Its Uses

Bactrim is effective against a wide range of bacteria. Examples of the bacteria it is effective against are:

• Vibrio cholerae bacteria that cause the diarrheal illness cholera
• Staphylococcus species including antibiotic-resistant MRSA strains that cause various infections
• Salmonella typhi bacteria responsible for typhoid fever
• Salmonella paratyphi bacteria causing paratyphoid fever
• Toxoplasma parasites causing toxoplasmosis infection
• Streptococcus pneumoniae bacteria resulting in pneumococcal pneumonia
• Klebsiella bacteria species causing pneumonia, bloodstream infections, urinary tract infections, meningitis and more
• Yersinia pestis bacteria which lead to plague
• Shigella bacteria species resulting in the intestinal infection shigellosis

Bactrim is used to treat infections caused by these bacteria. Examples of the FDA-approved uses of Bactrim include:

1. Travelers diarrhea for treatment and prophylaxis
2. Pneumocystis jirovecii pneumonia/Pneumocystis carinii pneumonia (PJP/PCP) both prophylactic and treatment
3. Otitis media in pediatrics only
4. Acute infective exacerbation of chronic bronchitis
5. Shigellosis
6. Toxoplasmosis both prophylactic and treatment
7. Urinary tract infections

Side effects of Bactrim

Bactrim is generally safe and well-tolerated when taken within recommended doses and as directed. However, it is not without side effects, just every other drug out there.

Some of the side effects of Bactrim are:

• Painful or swollen tongue
• Skin reactions such as rash or urticaria
• Ringing in the ears (Tinnitus)
• Nausea, vomiting, or dyspepsia
• Difficulty falling or staying asleep (Insomnia)
• Increased sensitivity to light (Photosensitivity)
• Loss of appetite (Anorexia)
• Persistent fatigue
• Generalized discomfort in the stomach (Dyspepsia)
• Dizziness or lightheadedness

These side effects are often mild and may resolve on their own.

About Amoxicillin

Amoxicillin belongs to the penicillin family of antibiotics. It is effective against a wide range of bacteria. Amoxicillin works by preventing bacteria from forming cell walls. This makes them lose integrity and also break down. 

Amoxicillin is generally safe and well-tolerated, but it can cause minor side effects like nausea, vomiting, and diarrhea. These are often mild and usually resolve on their own or upon the discontinuation of treatment.

Safety Tips when taking Bactrim and Amoxicillin together

1. Do not take Bactrim and amoxicillin together unless you are specifically directed by your doctor to do so.
2. Do not take either of these drugs if you are allergic to any penicillin or sulfur-containing drug.
3. Avoid taking alcohol while on Bactrim due to the risk of side effects. 
4. Report any side effects experienced while on either of these drugs to your doctor as soon as possible.

Final thoughts

While there is a clear-cut interaction between Bactrim and Amoxicillin, there is still a risk of developing Antibiotic-associated diarrhea from combining the two. As such, it is not recommended to take these two drugs together at the same time unless you are directed by your doctor to do so.

References

1. Wong, S., Santullo, P., O’Driscoll, J. et al. Use of antibiotic and prevalence of antibiotic-associated diarrhoea in-patients with spinal cord injuries: a UK national spinal injury centre experience. Spinal Cord 55, 583–587 (2017). 
2. Akhavan BJ, Khanna NR, Vijhani P. Amoxicillin. [Updated 2023 Nov 17]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-.
3. Kemnic TR, Coleman M. Trimethoprim Sulfamethoxazole. [Updated 2022 Nov 28]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-.