It's generally not recommended to give your dog vitamin C effervescent tablets. These are formulated for humans and are quite potent. Dogs, especially smaller breeds, have more sensitive systems and might not be able to handle the strength of these supplements. Regular or excessive consumption could lead to potential health risks.

If your dog has ingested a small amount of human vitamin C tablets, it might not be a cause for immediate panic. Keep a close eye on your dog for any adverse reactions. Should your dog develop diarrhea, it is best to consult your veterinarian for medical advice and treatment. It's essential to understand that human Vitamin C effervescent tablets are over-the-counter medications designed for humans with a relatively high potency. Even children are often advised to take only half a tablet. This makes them unsuitable for dogs, especially small dogs, as the dosage is usually too high. Prolonged use or overdosage can have detrimental effects on their health and even trigger conditions like vitiligo. Therefore, it’s best to avoid giving your dog human vitamin C tablets.
For supplementation, it is always best to use pet-specific vitamins. However, if you absolutely need to provide Vitamin C as an emergency replacement, giving just a quarter or less of the effervescent tablet might be considered, but this should not be a long-term solution.
How to Ensure Your Dog Gets Enough Vitamins
Generally, dogs can obtain their required vitamins from their diet. While commercial dog food does contain vitamins, the amounts might be insufficient for optimal growth and development. To boost your dog’s vitamin intake, include various vitamin-rich foods like organ meats (liver), egg yolks, milk, fresh meats, potatoes, and tomatoes. These provide a wide range of vitamins and help ensure a balanced nutritional intake.
If your dog shows signs of a severe vitamin deficiency, using specially formulated pet vitamin supplements is advisable. These are designed to suit a dog's digestive system, and usually contain a multitude of trace elements which will fulfil your dogs needs and prevent any further deficiencies. Therefore you don't need to worry about your pet lacking vitamins when on this.