When taken at the recommended doses, each ingredient in this supplement is very well tolerated and unlikely to cause any adverse side effects. That said, side effects are possible especially if exceeding the recommended dosage. Reported side effects of each ingredient are as follows.

Zinc – Nausea, diarrhea, and metallic taste are sometimes reported as side effects of Zinc and are more likely when taking high doses for prolonged periods of time. Sustained high dose Zinc supplementation can also cause copper deficiencies.

Vitamin C – Skin flushing, headaches, nausea, and upset stomach are side effects sometimes reported from Vitamin C supplements. These side effects are much more common when Vitamin C is used at high doses.

Elderberry – Nausea, muscle fatigue, dizziness, and numbness are sometimes reported as side effects of Elderberry, though these are much more common from consumption of raw berries than they are with Elderberry supplements.