diff --git a/src/MMseqsBase.cpp b/src/MMseqsBase.cpp
index b610a806b..2378621ba 100644
--- a/src/MMseqsBase.cpp
+++ b/src/MMseqsBase.cpp
@@ -124,11 +124,13 @@ std::vector<Command> baseCommands = {
                 "mmseqs createdb file1.fa file2.fa.gz file3.fa sequenceDB\n\n"
                 "# Create a seqDB from stdin\n"
                 "cat seq.fasta | mmseqs createdb stdin sequenceDB\n\n"
+                "# Create a seqDB from generic DB created by tar2db or another seqDB\n"
+                "mmseqs createdb inputDB sequenceDB\n\n"
                 "# Create a seqDB by indexing existing FASTA/Q (for single line fasta entries only)\n"
                 "mmseqs createdb seq.fasta sequenceDB --createdb-mode 1\n",
                 "Martin Steinegger <martin.steinegger@snu.ac.kr>",
-                "<i:fastaFile1[.gz|.bz2]> ... <i:fastaFileN[.gz|.bz2]>|<i:stdin> <o:sequenceDB>",
-                CITATION_MMSEQS2, {{"fast[a|q]File[.gz|bz2]|stdin", DbType::ACCESS_MODE_INPUT, DbType::NEED_DATA | DbType::VARIADIC, &DbValidator::flatfileStdinAndGeneric },
+                "<i:fastaFile1[.gz|.bz2]> ... <i:fastaFileN[.gz|.bz2]>|<i:stdin>|<i:inputDB> <o:sequenceDB>",
+                CITATION_MMSEQS2, {{"fast[a|q]File[.gz|bz2]|stdin|inputDB", DbType::ACCESS_MODE_INPUT, DbType::NEED_DATA | DbType::VARIADIC, &DbValidator::flatfileStdinAndGeneric },
                                                            {"sequenceDB", DbType::ACCESS_MODE_OUTPUT, DbType::NEED_DATA, &DbValidator::flatfile }}},
         {"appenddbtoindex",      appenddbtoindex,      &par.appenddbtoindex,      COMMAND_HIDDEN,
                 NULL,
diff --git a/src/util/createdb.cpp b/src/util/createdb.cpp
index dca9dfb7b..6b7bf799b 100644
--- a/src/util/createdb.cpp
+++ b/src/util/createdb.cpp
@@ -28,12 +28,17 @@ int createdb(int argc, const char **argv, const Command& command) {
     }
 
     bool dbInput = false;
+    bool isSeqDb = false;
     if (FileUtil::fileExists(par.db1dbtype.c_str()) == true) {
         if (filenames.size() > 1) {
             Debug(Debug::ERROR) << "Only one database can be used with database input\n";
             EXIT(EXIT_FAILURE);
         }
         dbInput = true;
+        // if par.hdr1 is not an empty string and the file exists
+        if (par.hdr1 != "" && FileUtil::fileExists(par.hdr1.c_str()) == true ) {
+            isSeqDb = true;
+        }
         par.createdbMode = Parameters::SEQUENCE_SPLIT_MODE_HARD;
     }
 
@@ -98,9 +103,14 @@ int createdb(int argc, const char **argv, const Command& command) {
 
     size_t fileCount = filenames.size();
     DBReader<unsigned int>* reader = NULL;
+    DBReader<unsigned int>* hdrReader = NULL;
     if (dbInput == true) {
         reader = new DBReader<unsigned int>(par.db1.c_str(), par.db1Index.c_str(), 1, DBReader<unsigned int>::USE_DATA | DBReader<unsigned int>::USE_INDEX | DBReader<unsigned int>::USE_LOOKUP);
         reader->open(DBReader<unsigned int>::LINEAR_ACCCESS);
+        if (isSeqDb) {
+            hdrReader = new DBReader<unsigned int>(par.hdr1.c_str(), par.hdr1Index.c_str(), 1, DBReader<unsigned int>::USE_DATA | DBReader<unsigned int>::USE_INDEX);
+            hdrReader->open(DBReader<unsigned int>::LINEAR_ACCCESS);
+        }
         fileCount = reader->getSize();
     }
 
@@ -126,8 +136,15 @@ int createdb(int argc, const char **argv, const Command& command) {
         }
 
         KSeqWrapper* kseq = NULL;
+        std::string seq = ">";
         if (dbInput == true) {
-            kseq = new KSeqBuffer(reader->getData(fileIdx, 0), reader->getEntryLen(fileIdx) - 1);
+            if (isSeqDb) {
+                seq.append(reader->getData(fileIdx, 0));
+                seq.append(hdrReader->getData(fileIdx, 0));
+                kseq = new KSeqBuffer(seq.c_str(), seq.length());
+            } else {
+                kseq = new KSeqBuffer(reader->getData(fileIdx, 0), reader->getEntryLen(fileIdx) - 1);
+            }
         } else {
             kseq = KSeqFactory(filenames[fileIdx].c_str());
         }
@@ -260,6 +277,10 @@ int createdb(int argc, const char **argv, const Command& command) {
     if (dbInput == true) {
         reader->close();
         delete reader;
+        if (isSeqDb) {
+            hdrReader->close();
+            delete hdrReader;
+        }
     }
 
     if (entries_num == 0) {