Zithromax: 7 things you should know
Medically reviewed by C. Fookes, BPharm Last updated on Aug 30, 2019.
1. How it works
- Zithromax is a brand (trade) name for azithromycin.
- Azithromycin is a type of antibiotic, called a macrolide. It kills bacteria by inhibiting bacterial protein synthesis.
- Azithromycin is used to treat infections caused by susceptible bacteria such as Mycobacterium avium, M. intracellulare, and Chlamydia trachomatis.
- Used to treat infections caused due to susceptible bacteria that occur on the skin, in the lungs, in the ears.
- Also treats some sexually transmitted infections; however, should not be relied upon to treat gonorrhea or syphilis.
- Used specifically for the treatment and prevention of mycobacterium avium complex (a type of respiratory infection) in people with advanced HIV. May be used in addition to other antibiotics.
- Active against a wide range of microorganisms and shows good penetration into human tissue. Some bacteria may be resistant (not killed by Zithromax).
- May be better tolerated and have more effective tissue penetration than other similar antibiotics such as erythromycin.
- Can be dosed once daily which improves adherence.
- May be used to treat bacterial infections in people intolerant of penicillins.
If you are between the ages of 18 and 60, take no other medication or have no other medical conditions, side effects you are more likely to experience include:
- Nausea, diarrhea, vomiting, abdominal pain, dyspepsia, flatulence, fatigue, and headache.
- Liver damage and it may affect liver function, sometimes fatally. Zithromax must be discontinued if any signs of liver dysfunction occur.
- May cause changes in the way the heartbeats, resulting in the development of cardiac arrhythmias. The risk is greater in people with a history of QT prolongation, on other drugs known to prolong the QT interval, with low levels of potassium or magnesium in their blood, and in those receiving anti-arrhythmic agents such as sotalol, amiodarone, and procainamide.
- Clostridium difficile-associated diarrhea is a potential side effect of almost all antibacterial agents, including Zithromax. Zithromax should be discontinued if this develops; symptoms include severe diarrhea.
- May cause severe skin reactions and photosensitivity (increased sensitivity to sunlight). Discontinue Zithromax and seek urgent medical advice should a rash develop.
- May interact with some other medications including warfarin and nelfinavir.
- Dosage may need decreasing in those with renal disease and may not be suitable for people with myasthenia gravis.
- May cause a condition in newborns called infantile hypertrophic pyloric stenosis. Symptoms may include vomiting and irritability.
Notes: In general, seniors or children, people with certain medical conditions (such as liver or kidney problems, heart disease, diabetes, seizures) or people who take other medications are more at risk of developing a wider range of side effects. For a complete list of all side effects, click here.
- May be taken with or without food; however, Zithromax tablets may be better tolerated if taken with food.
- Do not take at the same time as aluminum or magnesium-containing antacids.
- Discontinue Zithromax immediately and seek urgent medical advice if any signs of an allergic reaction (such as a rash or difficulty breathing) occur.
- Take exactly as directed and finish the course as prescribed by your doctor, even if you feel better. Skipping doses or not completing treatment can decrease the effectiveness of the treatment and promote the development of resistance.
- Although diarrhea is common with Zithromax, contact your doctor if you develop severe diarrhea especially if it is very watery or contains blood. Sometimes diarrhea may occur one to two months after starting or finishing a course of Zithromax.
- Contact your doctor immediately if you develop any signs of liver disease such as yellowing of the skin or whites of the eyes, upper right abdominal pain, rash, clay-colored stools, severe nausea, and vomiting.
- If you are allergic to other macrolides (such as clarithromycin, erythromycin, or telithromycin) do not take Zithromax. Also, avoid Zithromax if you have taken it before and it caused damage to your liver.
- Take Zithromax oral suspension immediately after reconstituting (mixing up). Do not store for later use.
- Avoid excessive exposure to sunlight or tanning beds. Use an SPF 30 or higher sunblock when outside and wear protective clothing because Zithromax can make you burn more easily in the sun.
6. Response and Effectiveness
- Takes between two and a half to just over three hours for peak concentrations to be reached. A loading dose (a higher than normal starting dose) may be used to reach steady concentrations sooner.
- Can be dosed once daily.
- May take several days before symptoms of the infection start to abate. Always finish the course as prescribed.
Medicines that interact with Zithromax may either decrease its effect, affect how long it works for, increase side effects, or have less of an effect when taken with Zithromax. An interaction between two medications does not always mean that you must stop taking one of the medications; however, sometimes it does. Speak to your doctor about how drug interactions should be managed.
Common medications that may interact with Zithromax include:
- BCG live (Theracrys)
- live typhoid vaccine
- NSAIDs, such as ibuprofen, diclofenac, and naproxen
In general, any medicine that can increase the risk of bleeding (such as clopidogrel, SSRI antidepressants, fish oils) may interact with Zithromax. Alcohol may increase the side effects of Zithromax and there is the potential for grapefruit products to interact with Zithromax; however, reports are uncommon.
Note that this list is not all-inclusive and includes only common medications that may interact with Zithromax, You should refer to the prescribing information for Zithromax for a complete list of interactions.
Zithromax (azithromycin) [Package Insert]. Revised 05/2019. Pfizer Laboratories Div Pfizer Inc. https://www.drugs.com/pro/zithromax.html
Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use Zithromax only for the indication prescribed.
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