As the threat of antibiotic resistance continues to grow, many frequently used antibiotics are no longer effective. Clindamycin is in the front rows of add-on antibiotics for serious infections but is rarely used alone. Read on to understand how it works and what side effects it can cause.
Disclaimer: The contents of this post are solely informational. Our goal is to outline the information available in the clinical and scientific literature. Please discuss your health concerns and medications with your doctor.
What is Clindamycin?
Clindamycin is an antibiotic approved for treating certain serious bacterial infections of the skin, muscles, lungs, and female reproductive system [R].
Clindamycin was developed in 1966 and has been commonly prescribed ever since. However, because of recent bacterial resistance and severe colitis associated with clindamycin use, other antibiotics are favorable for less serious infections [R].
Research suggests that clindamycin works by blocking the production of important proteins in bacteria, which stops their growth and spreading [R].
The most common side effect is diarrhea. Clindamycin is linked to a serious form of diarrhea that can lead to colon inflammation (colitis) and require special treatment. Severe colitis may be fatal [R].
Clindamycin comes in many forms, including capsules, liquid, creams, gels, lotions, vaginal suppositories, and IV injections.
Some common band names are Cleocin, Dalacin, Clindagel, Clindamax, Acanya, and Duac.
Mechanism of Action
Clindamycin and penicillins fight many of the same types of bacteria. Clindamycin is especially effective against bacteria that live and grow in places where there is little oxygen, such as the gut and under the skin. These pathogens are collectively known as anaerobic bacteria [R].
Research suggests that clindamycin works by binding to and blocking protein-making structures inside the bacteria. Lacking essential proteins, the bacteria can’t reproduce or release toxins. Scientists believe that this stops the infection from spreading and allows the immune system to destroy the remaining bacteria [R].
Clindamycin also likely kills parasites through the same mechanism. Although it was considered useful in treating malaria and other parasitic infections, other antimalarials are currently considered more effective [R, R].
One reason is that clindamycin clears parasites very slowly (in about 4 – 6 days). Sometimes, clindamycin is combined with other faster-acting malaria-fighting drugs However, this approach is not mentioned on clindamycin’s list of FDA-approved indications [R, R, R].
Take clindamycin exactly as prescribed and directed by your doctor. Follow all directions on your prescription label and read all medication guides or instruction sheets. Do not take more or less of it and do not take it more often than prescribed by your doctor.
Main Approved Indications
1) Skin and Soft Tissue Infections
Skin and soft tissue infections involve the skin, connective tissue under the skin, and muscles. Some are not a big health risk, such as minor wound infections. Others can be very serious and potentially fatal.
Animal bites can also cause skin and soft tissue infections. Clindamycin may be added on to other antibiotics, depending on the bacteria involved. Many of the bacteria found in animal bite wounds respond to clindamycin [R, R, R].
Flesh-eating bacterial infection is a rare, serious disease that rapidly destroys the skin and muscles. According to the evidence, clindamycin is a potential therapeutic choice because it blocks the production of bacterial toxins. In a study of 15 people, 93% of the bacteria that trigger this dangerous condition could be killed with a clindamycin-containing combination [R, R+].
2) Vaginal Infections
Bacterial vaginosis (BV) is caused by an overgrowth of certain bacteria in the vagina, which causes an imbalance of the normal flora. Symptoms may include increased vaginal discharge, fishy odor, and burning urination, but about 84% of women experience no symptoms at all [R].
About 21 million women in the US are affected by BV. Even after treatment, the infection comes back in 50% of women within a year. Although BV is not sexually transmitted, it can increase the risk of acquiring STIs (including HIV) [R, R, R].
The recommended treatment for BV is either metronidazole or clindamycin. Clindamycin vaginal cream is preferred due to fewer side effects, while vaginal suppositories are an alternative [R].
Clinical trials have found that clindamycin and metronidazole are equally effective for BV and are superior to other antibiotics. One study of 101 women found that clindamycin had a cure rate of 86.2% [R, R, R, R, R].
Although BV can also lead to premature birth and late miscarriage, it’s still unclear if the risks of antibiotic treatment outweigh the benefits in pregnant women. One clinical trial of 409 women with BV found that clindamycin reduced premature births by 60%. However, the evidence is still inconclusive, according to a larger analysis of 21 trials and over 7,800 women [R, R].
If you suspect BV and are pregnant (or planning to conceive), consult your doctor to screen for infections and discuss the best treatment strategies.
3) Pelvic Inflammatory Disease
Pelvic inflammatory disease (PID) is a bacterial infection of the upper genital tract in women (may include the uterus, fallopian tubes, and ovaries). It is usually caused by the spreading of sexually transmitted bacteria along the reproductive organs. PID often causes no symptoms, although some women experience abnormal vaginal bleeding, painful sex, and lower abdominal pain [R].
Early diagnosis and treatment are important since untreated PID can lead to permanent scarring, infertility, and chronic pelvic pain [R].
Clindamycin is not the first choice for treating PID, but can be used as an add-on in some cases (abscesses in ovaries). In one clinical trial of 119 people, antibiotic therapy including clindamycin had a 75% cure rate [R, R, R].
If you have symptoms of PID or an STI, see your doctor for a pelvic exam, vaginal discharge, and cervical culture analysis, and/or urine tests.
4) Toxic Shock Syndrome
Toxic shock syndrome (TSS) is a sudden and serious complication of bacterial infections. It is caused by the release of toxins that trigger a massive immune shock, which can seriously damage the organs or even lead to death. TSS made news in the 80s when a super absorbent tampon was recalled due to an epidemic of TSS cases [R].
Treatment of TSS requires hospitalization. Depending on the location of the infection, surgery may be needed. Multiple antibiotics are typically used to cover all possible strains of bacteria. Clindamycin is not the first choice, though, due to its high resistance and limited effects (blocking but not killing bacteria) [R+].
However, clindamycin may be an effective add-on in severe cases. It can decrease bacterial toxin production and act in synergy with other antibiotics. In one clinical trial of 84 people, it significantly reduced the number of deaths [R, R].
5) Heart Infections
Surgeries can sometimes introduce bacteria into the bloodstream, which can travel to the heart and trigger an infection. This is especially a concern in dental procedures, as the mouth is host to many bacteria. Antibiotics are used before surgery to prevent infections in people who are at risk or those undergoing gum manipulation [R, R].
People who have had the following are considered to be at an increased risk of heart infections [R]:
- Heart valve replacement
- History of heart infections
- Surgery to repair heart defects
- Heart transplant
In such cases, penicillins are the first choice due to their effectiveness and lower risk of side effects. Clindamycin is the second choice, in people allergic to penicillins. The antibiotic is usually taken 1 hour before the procedure in a single dose [R, R].
Clindamycin is also the second choice in preventing heart infections in other types of surgeries (throat, skin, or muscles). Again, antibiotics are only recommended in people at an increased risk of infections [R].
Despite their clinical use, it’s still unclear if this type of antibiotic use can actually prevent heart infections. In an analysis of 36 studies, the evidence to support it was limited and weak. As a result, some countries have shifted away from this strategy [R, R].
Other Less Common Uses
Gum disease is a chronic inflammation of the gums and ligaments that support the teeth, which is often triggered by the bacteria in dental plaques. Over time, gum disease can lead to deep pockets between the gums and teeth and tooth loss. Treatment involves plaque removal, surgery, or antibiotics [R].
Clindamycin is not among the preferred antibiotics for treating gum disease associated with tooth infections. It likely helps with aggressive forms of the disease. In a small study, clindamycin was effective at reducing gum bleeding and pocket size [R].
Pneumonia is typically caused by a bacterial infection of the lungs. It leads to inflammation of small air sacs in the lungs, trouble breathing, coughing, and fever. Pneumonia can become life-threatening, especially in the elderly and children.
Acne is often caused by a combination of factors, including diet, hormones, genetics, and bacterial infections. Acne affects 85% of teenagers and young adults, but you can get it at any age. In fact, over 50 million people in the US suffer from acne [R+, R+].
Severe acne cases can have a profound psychological and emotional impact, while bacteria often contribute to their development. Antibiotics are an option for mild acne and strongly recommended for moderate to severe acne.
Malaria is an infectious disease caused by parasites in the Plasmodium species, often spread through contact with mosquitos. It causes flu-like symptoms and can lead to death if untreated. There were 300-660 million cases of malaria worldwide in 2002, 90% of which were in Africa. Thanks to treatment initiatives, the number of new cases has gone down in recent years [R, R].
Antimalarial drugs are used to prevent and cure malaria. However, parasites have built resistance to many common antimalarials such as chloroquine [R].
Clindamycin, on the other hand, is 98% effective at eliminating malaria and has mild side effects. The drawback is that it takes twice as long to work, which is why it’s usually added to faster-acting antimalarials [R, R, R].
For example, in 130 children from Gabon, a country with highly-resistant malaria, chloroquine + clindamycin cured 70% of the cases. In comparison, chloroquine alone cured only 9%. Other studies had similar findings [R, R, R].
Clindamycin is also sometimes combined with another common antimalarial called quinine. In cell-based studies, these two drugs were hypothesized to have a synergistic effect. Some evidence suggests that, used together, they may reduce the treatment duration from 7 to 3 days [R, R].
Despite the strong potential of clindamycin combinations, its somewhat higher cost remains a hindering factor in parts of the world most affected by malaria [R].
Clindamycin may be prescribed for other uses. Ask your doctor or pharmacist for more information.
Clindamycin Side Effects & Precautions
This list does not cover all possible side effects. Contact your doctor or pharmacist if you notice any other side effects.
Call your doctor for medical advice about side effects. In the US, you may report side effects to the FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch. In Canada, you may report side effects to Health Canada at 1-866-234-2345.
Common Side Effects
Some common side effects of clindamycin include [R]:
- Abdominal pain
- Metallic taste
- Yellowing of the skin and eyes
Rare Side Effects
Some rare, but serious side effects include [R]:
- Inflammation of the colon
- C. difficile-associated diarrhea
- Severe allergic reactions
- Severe skin reactions
Topical forms of clindamycin tend to have fewer side effects.
Diarrhea is a common side effect of antibiotics. Antibiotic use can kill the good gut bacteria, allowing other harmful bacteria like C. difficile to grow and cause severe diarrhea. Symptoms of a C. difficile infection include diarrhea, abdominal pain, and fever. It can lead to severe inflammation of the colon and even death if left untreated [R].
Clindamycin is more likely to cause this type of diarrhea than other antibiotics. An early clinical trial found that 21% of people on clindamycin developed diarrhea and 10% inflammation of the colon [R, R].
Treatment consists of antibiotics that can kill C. difficile. However, this infection can be persistent and comes back in 10% – 25% of people. According to an analysis of almost 10K people, probiotics may reduce the risk of dangerous C. difficile infections by 60 – 70% [R, R].
Drug interactions can be dangerous and, in rare cases, even life-threatening. Let your doctor know about all drugs and supplements you are using or considering to reduce the risk of drug interactions.
Some antibiotics are known to reduce the effectiveness of birth control pills. The effect of clindamycin on birth control has not been studied. However, ask your doctor if you should use additional contraceptive measures while on this antibiotic [R].
Drugs Given During Surgery or Anesthesia
BCG is a drug used to treat some non-invasive bladder cancers. However, antibiotics can reduce its effectiveness. Clindamycin has not been researched, but research suggests its use should still be avoided in people taking BCG [R].
The antibiotics erythromycin and clindamycin can decrease each other’s effectiveness. According to the evidence, they shouldn’t be taken at the same time [R].
Clindamycin dose and therapy duration can vary depending on the disease, age, formulation, and hospital protocol. Always take this medication exactly as prescribed by your doctor.
As with all antibiotics, it is important to complete the full course of treatment. Stopping antibiotics early can lead to increased bacterial resistance.
Clindamycin capsules are available in strengths of 75 mg, 150 mg, and 300 mg.
Typical oral doses are [R]:
- 150 – 300 mg every 6 hours (serious infections)
- 300 – 450 mg every 6 hours (very severe infections)
- 8 – 16 mg/kg/day divided into 3 to 4 times daily (serious infections)
- 16 – 20 mg/kg/day divided into 3 to 4 times daily (very severe infections)
Limitations and Caveats
Considerable research has been done on clindamycin. Some diseases have been better studied than others.
It is important to note that antibiotic treatment should always be personalized. Different areas of the world have different resistance patterns, meaning the effectiveness of clindamycin can vary greatly.
Clindamycin’s role in preventing heart infections is not entirely clear. A large review of 36 studies found that the research supporting antibiotic prevention is limited and weak [R].
Due to the lack of strong evidence, the United Kingdom made new guidelines in 2008 to stop using antibiotics to prevent heart infections. A follow-up study was done to examine the effect of this change. Researchers found that antibiotic use dropped by ~79%, but there was no significant increase in cases of heart infections [R].
Clindamycin is indispensable in people with serious infections. Doctors prescribe this drug to people who have an infection that requires careful treatment and monitoring.
However, if you’re very prone to bacterial, yeast, or parasitic infections, you may talk to your doctor about complementary approaches to support your immune system.
For general wellness and immune support, the following may be recommended:
- Stress reduction
- Regular exercise
- A healthy diet
- Moderate sun exposure (to maintain normal vitamin D levels)
- Purported natural antibiotics
You may try the additional strategies listed above if you and your doctor determine that they could be appropriate. None of these strategies should ever be done in place of what your doctor recommends or prescribes.
Also, have in mind that supplements have not been approved by the FDA for medical use. Supplements generally lack solid clinical research. Regulations set manufacturing standards for them but don’t guarantee that they’re safe or effective. Speak with your doctor before supplementing.
Clindamycin is often added to other antibiotics or antiparasitic medications to fight off serious infections.
Make sure to take this medication exactly as prescribed by your doctor to avoid developing antibiotic resistance and ensure its effectiveness.
Your doctor may recommend adding probiotics like S. Boulardii to prevent and reduce severe diarrhea from clindamycin use.