Make your antibiotic medication as effective as possible by getting these answers before you leave the doctor's office or pharmacy.
Taking an Antibiotic? Here Are the Questions to Ask Your Doctor First
Updated on Dec. 09, 2024
You’ve almost certainly been prescribed antibiotics in your life. Maybe you had a nasty case of strep throat or needed to take precautions after a surgery. But even if you’re used to picking up a prescription from your local pharmacy and hoping it fights off your illness sooner rather than later, there are still specific questions you should ask your doctor before you start taking an antibiotic.
We spoke with expert doctors and pharmacists about what you should ask your doctor so your antibiotics work quickly and effectively.
What are antibiotics?
Antibiotics are medications used to treat or prevent bacterial infections only, typically in one of two ways, says Christina Kim, PharmD, BCIDP, a clinical pharmacy specialist at the Cleveland Clinic. “Antibiotics can either kill the bacteria (bactericidal) or inhibit their growth (bacteriostatic),” she says. “They work by targeting specific structures or functions within bacterial cells, such as their cell walls or DNA/RNA.”
Today, more than 100 different types of antibiotics are available that are organized into 9 different classes, according to the U.S. Centers for Disease Control and Prevention (CDC). These include penicillins, cephalosporins, and tetracyclines, to name a few.
Why you may need antibiotics
Bacteria are tiny live cells that generally aren’t harmful. In fact, some bacteria are essential for good health. But certain types can cause infections that make you sick. Mild infections, such as skin infections, urinary tract infections, or ear infections, may heal on their own, though antibiotics help cure the infection if it doesn’t go away or it gets worse.
Other bacteria cause much more serious infections, including pneumonia, food poisoning, chlamydia, and meningitis—and in these cases, antibiotics can be life-saving.
Antibiotics do not treat viral infections
Here’s the catch: Antibiotics can’t treat viral infections (like cold and flu sinus infections or bronchitis), parasite-based infections, or those caused by fungi, such as athlete’s foot and yeast infections, explains Shira Doron, MD, chief infection control officer at Tufts Medicine and hospital epidemiologist at Tufts Medical Center.
“For certain viruses, there are antiviral medications such as paxlovid or molnupiravir for COVID-19 virus and oseltamivir (Tamiflu) for influenza,” adds Jeremy Blanchard, MD, PhD, a board-certified family medicine physician with NewYork-Presbyterian/Columbia University Irving Medical Center. “There are also antifungal medications for fungal infections.”
Questions to ask your doctor before taking antibiotics
1. Do I need an antibiotic?
Every patient should verify and understand the rationale as to why they’re being prescribed an antibiotic, says Norman Tomaka, BS, Pharm.MS, FAPhA, a clinical consultant pharmacist. According to a 2022 annual report from the CDC, at least 28% of antibiotics prescribed are not needed.
“Antibiotic resistance is rising globally at an alarming rate,” Dr. Doron re-emphasizes. “Before taking an antibiotic, ask your doctor if it is really necessary.”
She says sometimes a “watch and wait” approach—where you have the prescription but do not fill it unless your condition worsens—can help to avoid using unnecessary antibiotics. “When you do see the doctor for an infection, try not to go in with the expectation that an antibiotic is the best solution.”
2. When should I take antibiotics?
“There’s a difference between taking three times a day versus every eight hours,” says Barbara Young, PharmD, former editor of Consumer Medication Information for the American Society of Health-System Pharmacists.
Antibiotics work best when taken at a consistent time between doses by keeping the right amount of the medication in your bloodstream. Make sure to follow the instructions for your specific medication. For instance, you may need to take your antibiotic every 12 hours twice a day or every 8 hours three times a day.
3. Should my antibiotic be taken with food?
Eating when you take any medication could affect how the drug is absorbed in your system. Taking an antibiotic with food could prevent nausea from a drug that might irritate the stomach, says Vincent Hartzell, PharmD, RPh, a national faculty member with the American Pharmacists Association and president of Hartzell’s Pharmacy in Pennsylvania.
But it’s even more important to follow directions if a medication is meant to be taken with an empty stomach because the food might block the drug from being absorbed in the bloodstream, he says.
4. Are there any foods I should avoid while on antibiotics?
“There may be interactions when antibiotics are taken with food,” Dr. Kim says. For instance, dairy products containing calcium, such as cheese, milk, and yogurt, may bind to certain antibiotics—including tetracycline, norfloxacin, ciprofloxacin, and levofloxacin—and reduce their absorption. “It is usually advised to take these antibiotics at least two hours before or after consuming dairy.”
Keep in mind that there are many non-dairy foods high in calcium as well, such as:
- leafy greens
- tofu
- salmon
- fortified drinks (like orange juice or soy milk)
- fortified cereals
Citric acid can also interfere with how well your antibiotics work by reducing their absorption into your system, according to 2023 research published in the International Journal of Molecular Sciences. Foods high in citric acid primarily include citrus fruits like oranges, grapefruits, and lemons. Like calcium-containing foods, it’s best to avoid citrus foods for two hours before and after taking an antibiotic.
5. Should I drink a full glass of water with my medication?
A glass of water can dilute stomach contents and help get an antibiotic through before your belly can get irritated, Tomaka says. While drinking enough water can help prevent nausea from most medications, other drugs need a full glass for proper absorption, he says. “A capsule prevents dissolution until it gets into the stomach, and taking it with water makes the difference between a good and bad experience,” Tomaka says.
6. Should I take a probiotic, too?
“Most antibiotics aren’t specific to just kill the bacteria causing your infection,” Dr. Hartzell says. “They kill a variety of bacteria, including the ones you don’t want to kill.” When medications attack good bacteria—like the types that promote a healthy gut—you might end up with an upset stomach, UTI, or yeast infection.
“Because these [side effects] are due in part to a disruption of the body’s normal flora, some people find that probiotics or yogurts with live active cultures can help,” Dr. Doron says.
7. What should I do if I miss a dose?
Whether you set a timer on your phone or use a medication reminder app, taking your antibiotic dose on time is the best way to ensure a consistent amount of the drug stays in your system to fight off bacteria. Missing an antibiotic dose can allow the bacteria to multiply, potentially prolonging your infection and necessary treatment, according to research published in the Journal of Surgical Research.
If you miss a dose of your medication, check with your doctor about how and when to continue taking it, Dr. Blanchard advises. But in general, if you miss one dose of your antibiotic, take it as soon as you remember. This will help get the drug back into your system at therapeutic levels.
However, if it’s nearly time for your next dose, skip the one you missed and continue taking your medication as scheduled. It’s important that you don’t double up on your antibiotic to try and make up for the one you missed, as this could lead to a greater risk of side effects.
8. When should I start to feel better?
“It can take up to 72 hours to start feeling better on antibiotics, even if they are working,” Dr. Doron says.
If you still don’t feel better after this window, there are a few potential reasons why. Your symptoms might not be related to an infection, or your infection might be viral or fungal, not bacterial. She adds, “You might have an infection caused by antibiotic-resistant bacteria, which is becoming more and more common, and warrants changing to a different antibiotic.”
If your symptoms aren’t getting better within a few days of taking antibiotics, talk to your doctor. “Your doctor may perform a culture of an appropriate specimen (such as a throat swab, urine sample, or pus from a wound), which can help determine if there is a bacterial infection, what organism is causing it, and what antibiotics are likely to work,” Dr. Doran explains. Some infections also need to be drained or debrided to get better.
That said, take note that it’s important to finish the full course of antibiotics as prescribed even if you start feeling better, Dr. Kim says. “Stopping antibiotics early may cause some bacteria to survive and worsen your current infection and/or contribute to antibiotic resistance.”
9. Are there side effects to this antibiotic?
According to 2020 research published in Canadian Family Physician, all antibiotics can cause gastrointestinal (GI) side effects, such as:
- nausea
- vomiting
- diarrhea
- abdominal pain
- loss of appetite
- bloating
“Ask about other side effects specific to certain antibiotics, like an increased risk of sunburn and liver or kidney effects,” Dr. Doron advises.
Per the research, some potential medication-specific side effects to be aware of (in addition to GI issues) include:
- Penicillins (includes amoxicillin): Yeast infection, skin rash, headache.
- Cephalosporins: Headache, dizziness.
- Non–β-lactams: Headache, vaginitis, rhinitis, back pain, dizziness, sore throat, pain.
- Lincosamides (such as clindamycin): Skin rash.
- Linezolid: Fever, dizziness.
- Methenamine: Urinary changes with large doses.
- Metronidazole: Metallic taste, yeast infection.
- Nitrofurantoin: Headache, gas.
- Quinolones (such as ciprofloxacin and levofloxacin): Headache, joint stiffness, muscle pain, numbness, tingling, brain fog.
- Sulfonamides: Elevated blood potassium levels.
- Tetracyclines (includes doxycycline and minocycline): Sun sensitivity, weight gain, throat irritation, dizziness, weakness.
- Vancomycin: Fatigue, back pain, headache.
- Azoles (such as fluconazole): Dizziness, headache, metallic taste, abnormal dreams, respiratory symptoms.
In general, if you are experiencing symptoms after starting a new medication, it is important to discuss these with your doctor, Dr. Blanchard says. Depending on the severity, you may be able to switch to another medication.
However, if you experience signs of an allergic reaction—such as shortness of breath or hives—seek medical attention.
10. Will this antibiotic make me tired?
“Fatigue is a common side effect for many different antibiotics,” Dr. Blanchard says. Certain antibiotics, such as vancomycin, do list feeling tired as a potential side effect. However, other common antibiotic side effects include headaches, muscle aches, and neurological effects like dizziness—all of which can drain your energy.
But Dr. Blanchard points out an important distinction: Do antibiotics make you tired, or is your illness making you feel run down? “Fatigue is also a symptom of many different types of infections that the antibiotic may be treating,” he explains.
Antibiotics can do some heavy lifting when it comes to healing an infection, but your immune system is hard at work, too. So, whether you have a mild skin infection or you’re fighting a tough respiratory infection, make sure to support your immune system function by getting plenty of rest, drinking enough water, and powering your body with immune-boosting foods.
11. Is it safe to drink alcohol when taking this antibiotic?
Alcohol consumption with certain antibiotics can cause severe reactions, Dr. Kim says—particularly with the antibiotics metronidazole or tinidazole. Metronidazole is a common antibiotic used to treat vaginal infections and skin infections, while tinidazole treats parasitic infections.
This means if you’re taking either of these antibiotics, you must stay away from all alcohol, even the trace amounts found in some mouthwashes and cold medicines.
While moderate alcohol consumption doesn’t interact with most other antibiotics, experts still advise against mixing the two. This is because alcohol can cause dehydration and poor sleep, both of which can weaken your immune system, delaying your recovery.
Plus, according to the Cleveland Clinic, there isn’t a lot of conclusive research regarding alcohol use and antibiotics, largely because both drugs can affect everyone differently. It’s best to stay sober until you’re feeling better.
12. Is it safe to drink caffeine on antibiotics?
Caffeine is generally safe with most antibiotics, Dr. Kim says. “However, some antibiotics may interfere with the body’s ability to metabolize caffeine, leading to increased concentrations of caffeine and, thus, increased side effects such as jitteriness and insomnia.”
One example is a class of antibiotics called fluoroquinolones, which are used to treat bacterial bronchitis, pneumonia, sinusitis, urinary tract infections, skin infections, bacterial gastroenteritis, and more.
13. Can I take antibiotics if I’m pregnant?
Antibiotics are generally safe to take if you’re pregnant. Still, Dr. Doron advises, “Always tell the person prescribing you antibiotics if you are pregnant or think you might be pregnant.” She adds, “Since some antibiotics can cause adverse effects to the fetus, your doctor will want to choose an antibiotic that is known to be safe in pregnancy.”
14. Can I use old antibiotics in my medicine cabinet?
“It is never a good idea to take antibiotics that haven’t been prescribed by your doctor for your current condition,” Dr. Doron says. “Since different types of bacterial infection need different types of antibiotics, you cannot assume that what worked for you the last time will work this time.”
Plus, you should have your doctor tell you how many days of antibiotics you need to take.
“Additionally, expired antibiotics may not fully treat an infection,” Dr. Kim adds.
15. Am I able to crush the pill?
If you have trouble swallowing pills, check with a doctor or pharmacist before crushing it because it might not absorb the same way a whole capsule would, Young says. Many antibiotics also have a liquid form available, which could be a better option, she says.
16. Is this antibiotic safe with other medications I take?
“Whenever you get a new prescription, be sure to tell your doctor and pharmacist not only about what medications you are taking but also about supplements and herbals,” Dr. Doron says.
While it’s rarely used, the antibiotic rifampin is known to interfere with birth control, for example. Some antibiotics can affect the metabolism of certain blood thinners, such as warfarin, and increase the risk of bleeding, Dr. Kim adds. “[Others] may interact with selective serotonin reuptake inhibitors (SSRIs) and increase the risk of adverse effects.”
Minerals such as calcium, iron, and zinc can bind to certain antibiotics, particularly the fluoroquinolones like ciprofloxacin, levofloxacin, norfloxacin, and ofloxacin. They can impair their absorption, reducing the antibiotic’s effectiveness.
Iron supplements also interfere with tetracyclines, including doxycycline and minocycline. If you take these nutritional supplements (including in multivitamin form), Dr. Kim explains, “It is often recommended to separate doses by at least two hours.”
17. If I had a reaction in the past, am I allergic to this medication?
An allergy to an antibiotic means that not only do you have to avoid that medicine, but you may also need to avoid other antibiotics in the same drug family, Tomaka says.
But just because you had a reaction when you were younger doesn’t necessarily mean you need to avoid it now. Your system may be able to tolerate a different formulation of penicillin, for instance. Plus, your reaction might not have been an allergy in the first place. Ampicillin, for example, can cause rashes in children related to histamine release, not an allergy.
Note that side effects like nausea and vomiting are normal and not signs of an allergy.
You should still stick with a medication you know you feel comfortable with, but it might be worth a future visit to test whether you’re truly allergic. “Pick the safest, most conservative route if you’re not going to be monitored,” Tomaka says. “The value of finding out about an allergy is to get the most updated information.”
Are antibiotics safe?
“All antibiotics have specific indications, risks, benefits, and side effects,” explains Dr. Blanchard. “Individuals may also have different responses to antibiotics based on allergies, other medications they are taking, specific factors such as age, and individual pharmacokinetics (how your body handles a medication), which impact the way medications are metabolized.”
In general, if your doctor determines that you do need an antibiotic and you take it as directed, the benefits usually outweigh the risks, according to the CDC. But taking too many antibiotics increases the risks of side effects—and taking antibiotics when you don’t need them can also lead to side effects.
Still, “it can be hard to tell if an infection is caused by bacteria—sometimes even doctors aren’t sure,” Dr. Doron says. “Infectious Disease doctors are specialists who help determine the cause of and treatment for infections and sometimes need to be brought in to help with tricky cases.”
What you should know about antibiotic resistance
“It’s incredibly important to take antibiotics only when you need them,” Dr. Doron explains. “We now know that the more antibiotics you take, the more resistance develops,.”
Antibiotic resistance is a serious global health issue that occurs when bacteria change in a way that our antibiotic medicines can no longer kill them or stop their growth. That means bacterial infections become harder and harder to treat—and it can take longer for a doctor to find a medication that works. This delays treatment, which can lead to more serious outcomes. And according to 2024 data from the CDC, more than 2.8 million antibiotic-resistant infections occur each year.
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Sources
- US Centers for Disease Control and Prevention (CDC): “Antibiotic Resistance & Patient Safety Portal Outpatient Antibiotic Prescription Data”
- CDC: “Healthy Habits: Antibiotic Do's and Don'ts”
- CDC: “Outpatient Antibiotic Prescribing in the United States”
- International Journal of Molecular Sciences: “Citric Acid Confers Broad Antibiotic Tolerance through Alteration of Bacterial Metabolism and Oxidative Stress”
- Journal of Surgical Research: “The Effects of Missed Doses of Antibiotics on Hospitalized Patient Outcomes”
- Canadian Family Physician: “Update on the adverse effects of antimicrobial therapies in community practice”
- Cleveland Clinic: "Why You Should Avoid Alcohol on Antibiotics"
- CDC: “Antimicrobial Resistance Facts and Stats”
Medically reviewed by 
