Adverse effects
The most common side effects of ketosis include headache, fatigue, dizziness, insomnia, difficulty in exercise tolerance, and constipation, and nausea especially in the first days and weeks after starting a ketogenic diet.
[26] Breath may develop a sweet, fruity flavor due to production of acetone that is exhaled due to its high volatility.
[6]
Most adverse effects of long-term ketosis reported are in children due to its longstanding acceptance as a treatment for pediatric epilepsy. These include compromised bone health, stunted growth, hyperlipidemia, and kidney stones.
[28]