The “common cold” is the most common infection one can contract. There are over 220 viral strains that can cause cold symptoms. Rhinovirus is the most frequent, responsible for 50% of infections. 

Simple Strategies to Help Strengthen the Immune System:

  • Frequent handwashing with anti-microbial soap and warm water
  • If you have a cough, cough into your sleeve, not your hand 
  • Use your knuckles instead of fingertips to push open doors or press elevator buttons
  • Wear a facemask when using public transportation
  • Remain well hydrated
  • Consume a diet high in antioxidant containing foods (Fruits, vegetables)
  • Minimize the intake of sugar and processed foods

The following supplements may also be beneficial in preventing viral infections and fighting cold symptoms.

Vitamin D

In my Southern California Practice, 80 percent of patients are vitamin D deficient. The incidence is higher in less sunny climates. I routinely recommend my patients supplement with vitamin D.

A 2019 study in the International Journal of Environmental Research and Public Health concluded that those with higher blood levels of vitamin D were at lower risk for Upper Respiratory Infections compared to those with lower vitamin D blood levels. 

In a 2017 study in the British Medical Journal, researchers evaluated 25 randomized controlled trials which included 11,321 participants, whose ages ranged from babies to 95 years of age. 

In total, vitamin D supplementation reduced the risk of an upper respiratory infection by 12 percent. Those who had vitamin D blood levels less than 25 nmol/L (10 ng/dl) noticed the biggest benefit and saw a 70% decrease in infection rate when they were supplemented. In patients who had a vitamin D level greater than 25 nmol/L (10 ng/dl), a 25% reduction in respiratory infections was seen.

Suggested dose: 1,000-2,000 IU for children and 2,000 to 5,000 IU daily for adults.


As we age, the absorption of important minerals like zinc can be impaired. The WHO or World Health Organization estimates that up to one-third of the world population is deficient in Zinc. Additionally, poor dietary intake of zinc-containing foods or routine ingestion of alcohol can also result in chronically low zinc levels. Zinc deficiency is associated with increased risk for infection, along with other issues.

A 2016 study in the British Journal of Clinical Pharmacology concluded, “common cold patients may be encouraged to try zinc lozenges for treating their colds” while a 2017 study concluded, “common cold patients may be instructed to try zinc  lozenges within 24 hours of the onset of symptoms.” 

Another 2017 study showed both zinc gluconate lozenges and zinc acetate lozenges are equally effective. 

Lastly, a 2018 study in the Journal of Immunology Research showed that a zinc deficiency could weaken the immune system and that zinc-dependent proteins are required to achieve an optimal immune response against invading pathogens.

Suggested dose: zinc lozenges, 30 mg as directed on the label. Also available in capsules and multivitamins.


Elderberry (Sambucus sp.), a flowering plant, has been used for hundreds of years for medicinal purposes by native populations all over the world. In recent years, elderberry’s popularity has caught on. 

A 2016 study showed that elderberry could reduce the duration of cold symptoms in airline travelers. 

A 2019 study in Complementary Therapies in Medicine evaluated 180 participants.

They found that Elderberry could substantially reduce upper respiratory infection symptoms. They concluded that “These findings present an alternative to antibiotic misuse for upper respiratory symptoms due to viral infections, and a potentially safer alternative to prescription drugs for routine cases of the common cold and influenza

Lastly, a 2001 study and 2002 study both showed elderberry’s benefit in strengthening the immune system response. 

Elderberry is available as a supplement, syrup, gummy, and lozenges.

Additional Supplements

Other supplements that may be helpful include vitamin C and probiotics while the essential oils rosemarypeppermint, and eucalyptus can reduce symptoms of a cold.


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