There are various causes of underweight like inadequate food intake, prolonged meal time gaps, and increased physical activity weight increasing food intake. Other reasons are mostly medical conditions like TB, cancer, malabsorption, hyperthyroidism, and anorexia nervosa etc. Natural ways of gaining weight is advisable. Oraxin contains cyproheptadine. It can be used to increase appetite only for short term. If your appetite is normal then there is no need to take it. Its long term used will cause side effects. Adopt natural ways of gaining weight. Advice 1. Exercise – start workout in gym at least for half an hour for 4 – 5 days in a week regularly. start with a balanced mix of cardio, weight training and flexibility exercises 2. Take natural high protein like egg, soya bean, pulses, meat, and milk. 3. Choose food with nutritional calories like potato, banana and dry fruits 4. Drink 4 – 5 liters of water daily 5. Chew the food properly to make it easily digestible 6. Avoid excess intake tea and coffee after meal as they contain tannin which hinders absorption of minerals like iron Thanks