There is nothing wrong with taking medication for mental illness
Question

                I am a young man, and from the time I was born I have had some problems – I am very sensitive and introverted, and I suffer from fear. Please note that this is a hereditary disease. My father and mother suffered from it, as did my grandmother, my paternal aunt and her daughter. I know that it results from the lack of a substance in the brain that my body cannot produce, and that this deficiency can be made up for with medication. Does this go against sharee’ah? Is it regarded as changing the creation of Allaah?.
Praise be to Allah.
    Medical treatment is allowed in Islam in general terms, and 
    is not regarded as changing the creation of Allaah. The ruling among the 
    scholars is that it is either permitted (mubaah) or recommended (mustahabb). 
    The Hanafis and Maalikis are of the view that medical treatment is 
    permitted, and the Shaafa’is and some Hanbalis are of the view that it is 
    mustahabb. The view of most of the Hanbalis is that it is better not to do 
    it. Ahmad ibn Hanbal narrated that Anas (may Allaah be pleased with him) 
    said: The Messenger of Allaah  (peace and blessings of Allaah be upon 
    him) said: “When Allaah created the disease, He also created the cure, so 
    seek the cure.” Narrated by Ahmad, 12186; classed as hasan by al-Albaani in
    al-Silsilah al-Saheehah, 1633. 

    It was narrated that Usaamah ibn Shurayk (may Allaah be 
    pleased with him) said: The Bedouin said: “O Messenger of Allaah, should we 
    not treat sickness?” He said, “Yes, O slaves of Allaah, treat sickness, for 
    Allaah did not send down any disease but He also sent down its cure, except 
    for one disease.” They said, “O Messenger of Allaah, what is it?” He said, 
    “Old age.” Narrated by al-Tirmidhi, 2038; classed as saheeh by al-Albaani in
    Saheeh al-Tirmidhi. 

    Old age refers to the weakness and illnesses that come with 
    old age, for which there is no cure. 

    It makes no difference with regard to medical treatment 
    whether the sickness is physical, mental or nervous. The word da’ (disease, 
    sickness) in the ahaadeeth is general in meaning and includes all kinds of 
    sickness. 

    Shaykh ‘Abd al-‘Azeez ibn Baaz (may Allaah have mercy on him) 
    said: 

    It is permissible to treat sickness according to scholarly 
    consensus. The Muslim may go to a doctor for internal sickness, injuries, 
    nervous problems and so on, for him to diagnose his sickness and treat it 
    appropriately, using medicines that are permitted according to Islam, 
    according to his medical knowledge, because this comes under the heading of 
    taking the usual means, and it does not contradict the idea of putting one's 
    trust in Allaah. Allaah has sent down the disease and He has sent down the 
    cure; those who know it know it, and those who do not know it do not know 
    it, but Allaah does not put the healing for His slaves in something that He 
    has forbidden to them. 
It is not permissible for 
    a sick person to go to the soothsayers or fortunetellers who claim to have 
    knowledge of the unseen, in order to find out from them what his sickness 
    is. Nor is it permissible for him to believe what they tell him, for they 
    speak without knowledge or they summon the jinn to ask their help in doing 
    what they want to do. The ruling on these people is that they are kaafirs 
    who are misguided, if they claim to have knowledge of the unseen… 

    Majmoo’ Fataawa al-Shaykh Ibn Baaz, 
    3/274 

    Although it is permissible to use physical medicine, the sick 
    person should also look for spiritual remedies as prescribed in Islam, in 
    which Allaah has put the cure for both physical and mental illness, such as 
    ruqyah as prescribed in Islam, in which Qur’aan or words narrated in the 
    Sunnah are recited. 

    The scholars of the Standing Committee said, answering a 
    similar question: 

    Trust in Allaah and think positively of Him; delegate your 
    affairs to Him, and do not despair of His mercy, bounty and kindness, for He 
    has not sent down any disease but He has also sent down the cure. You should 
    take the means and continue to consult specialist doctors who have knowledge 
    of disease and its treatment. Recite Soorat al-Ikhlaas, Soorat al-Falaq and 
    Soorat al-Naas over yourself three times, and blow into your hands after 
    each time, and wipe your face and whatever you can reach of your body. Do 
    that repeatedly night and day and when going to sleep. Also recite over 
    yourself Soorat al-Faatihah at any time of night or day, and recite Aayat 
    al-Kursiy when you lie in your bed at night. These are the best ruqyahs with 
    which a person may treat himself and protect himself from evil. Call upon 
    Allaah by reciting the du’aa’ for one who is in distress, and say:

    “Laa ilaaha ill-Allaah al-‘Azeem al-Haleem, laa ilaaha 
    ill-Allaah rabb al-‘arsh il-‘azeem, laa ilaaha ill-Allaah rabb al-samawaati 
    wa rabb al-ard wa rabb al-‘arsh il-‘azeem (There is no god but Allaah, 
    the All-Mighty, the Forbearing, there is no god but Allaah, the Lord of the 
    mighty Throne, there is no god but Allaah, Lord of the heavens, Lord of the 
    earth, and Lord of the mighty Throne).”

    Also treat yourself with the ruqyah of the Messenger of 
    Allaah  (peace and blessings of Allaah be upon him): 

    Allaahumma Rabb an-naas, mudhhib al-ba’s ishfi anta 
    al-Shaafi, laa shaafiya illa anta, shifaa’an laa yughaadir saqaman 
    (O Allaah, Lord of mankind, the One Who relieves hardship, grant healing, 
    for there is no healer but You, a healing that leaves no trace of sickness) 

    And recite other dhikrs and ruqyahs and du’aa’s which are 
    mentioned in the books of hadeeth, and which are mentioned by al-Nawawi in
    Riyaadh al-Saaliheen and Kitaab al-Adhkaar. 

    Fataawa al-Lajnah al-Daa’imah, 
    1/297 
We ask Allaah, the Lord 
    of mankind, to take away your pain, and to heal you of what you are 
    suffering. We urge you to be patient and to seek reward with Allaah for what 
    has befallen you, and we hope that Allaah will reward you and relieve you of 
    your distress. 
And Allaah knows 
    best.